Implementation of design during execution & service life — Implementation of design during execution & service life (JRC139606)

ISSN 1831-9424 Implementation of Design during Execution & Service Life Guidelines for the application of the 2nd generation of Eurocode 7: Geotechnical design Bogusz, W., Caplane, C., Hard, D., Idda, K., Ingram, P., Kanty, P., Kushwaha, A., Nayrand, N., Sand, O., Sciarretta, F., Tsitsas, G., Vogt, H. Edited by Hard, D. 2024 EUR 40128

This document is a publication by the Joint Research Centre (JRC), the European Commission’s science and knowledge service. It aims to provide evidence-based scientific support to the European policymaking process. The contents of this publication do not necessarily reflect the position or opinion of the European Commission. Neither the European Commission nor any person acting on behalf of the Commission is responsible for the use that might be made of this publication. For information on the methodology and quality underlying the data used in this publication for which the source is neither Eurostat nor other Commission services, users should contact the referenced source. The designations employed and the presentation of material on the maps do not imply the expression of any opinion whatsoever on the part of the European Union concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries.

EU Science Hub JRC139606 https://joint-research-centre.ec.europa.eu EUR 40128

Print ISBN 978-92-68-22437-3 ISSN 1018-5593 doi:10.2760/9429668 PDF ISBN 978-92-68-22436-6 ISSN 1831-9424 doi:10.2760/8383117

KJ-01-24-170-EN-C KJ-01-24-170-EN-N

Luxembourg: Publications Office of the European Union, 2024

© European Union / Bogusz, W. / Caplane, C. / Hard, D. / Idda, K. / Ingram, P. / Kanty, P. / Kushwaha, A. / Nayrand, N. / Sand, O. / Tsitsas, G. / Vogt, H., 2024

The reuse policy of the European Commission documents is implemented by the Commission Decision 2011/833/EU of 12 December 2011 on the reuse of Commission documents (OJ L 330, 14.12.2011, p. 39). Unless otherwise noted, the reuse of this document is authorised under the Creative Commons Attribution 4.0 International (CC BY 4.0) licence (https://creativecommons.org/licenses/by/4.0/). This means that reuse is allowed provided appropriate credit is given and any changes are indicated. For any use or reproduction of photos or other material that is not owned by the European Union permission must be sought directly from the copyright holders. - Cover page illustration, © Adriaan Van Seters, 2000 How to cite this report: European Commission, Joint Research Centre, Bogusz, W., Caplane, C., Hard, D., Idda, K., Ingram, P., Kanty, P., Kushwaha, A., Nayrand, N., Sand, O., Sciarretta, F., Tsitsas, G. and Vogt, H., Implementation of Design during Execution and Service Life, Hard, D. editor, Publications Office of the European Union, Luxembourg, 2024, https://data.europa.eu/doi/10.2760/8383117, JRC139606.

Contents Abstract ...................................................................................................................................................................................................... 5 Foreword .................................................................................................................................................................................................... 6 Acknowledgements ........................................................................................................................................................................... 10 1 Introduction .................................................................................................................................................................................... 11 1.1 Context.................................................................................................................................................................................... 11 1.2 Objectives.............................................................................................................................................................................. 11 1.3 Target audience................................................................................................................................................................. 11 1.4 Scope ....................................................................................................................................................................................... 12 1.5 Application of this guide............................................................................................................................................... 12 2 Implementation of design in execution .......................................................................................................................... 13 2.1 General aspects of successful “implementation of design in execution” ......................................... 13 2.2 Definition of terms........................................................................................................................................................... 13 2.2.1 Supervision ............................................................................................................................................................. 13 2.2.2 Inspection ................................................................................................................................................................ 13 2.2.3 Monitoring............................................................................................................................................................... 14 2.2.4 Maintenance .......................................................................................................................................................... 14 2.2.5 Execution specification .................................................................................................................................... 14 2.2.6 Designer ................................................................................................................................................................... 14 2.3 Definition of project phases ....................................................................................................................................... 15 2.4 Roles and responsibilities............................................................................................................................................. 17 2.4.1 Roles and responsibilities: General ........................................................................................................... 17 2.4.2 Roles and responsibilities: typical roles.................................................................................................. 19 2.4.3 Checklist proposal .............................................................................................................................................. 19 2.5 Key design factors and risks ...................................................................................................................................... 21 2.5.1 Code references and tolerances................................................................................................................. 21 2.5.2 Soil and rock stratification ............................................................................................................................ 22 2.5.3 Soil and rock parameters ............................................................................................................................... 22 2.5.4 Groundwater and assumed groundwater lowering levels........................................................... 22 2.5.5 Adjacent assets, structures and utilities................................................................................................ 22 2.5.6 Contamination of soils and water............................................................................................................. 23

2.5.7 Permanent and temporary traffic loads assumed .......................................................................... 23 2.5.8 Design lifetime, construction stages and their assumed maximum durations............... 23 2.6 Effective communication and documentation ................................................................................................. 23 2.6.1 Installation of regular communication lines........................................................................................ 23 2.6.2 Interface coordination...................................................................................................................................... 24 2.6.3 Dealing with errors and omissions ........................................................................................................... 24 2.6.4 Dealing with change requests ..................................................................................................................... 25 2.6.5 Design quality ....................................................................................................................................................... 25 2.7 Further guidance ............................................................................................................................................................... 26 2.7.1 The use of National Specifications ........................................................................................................... 26 2.7.2 Geotechnical Baseline Reports (GBR) ...................................................................................................... 26 3 Establishing Plans....................................................................................................................................................................... 27 3.1 General concepts .............................................................................................................................................................. 27 3.1.1 Introduction............................................................................................................................................................ 27 3.1.2 Links to standards.............................................................................................................................................. 27 3.1.3 Terms......................................................................................................................................................................... 28 3.2 Case study 1 – Embankment..................................................................................................................................... 29 3.2.1 Introduction............................................................................................................................................................ 29 3.2.2 Data............................................................................................................................................................................ 29 3.2.3 Summary of plans for supervision, inspection, monitoring and maintenance................. 30 3.2.4 Supervision plan - comments ...................................................................................................................... 31 3.2.5 Inspection plan – comments ........................................................................................................................ 32 3.2.6 Monitoring plan – comments ....................................................................................................................... 33 3.2.7 Maintenance plan – comments................................................................................................................... 34 3.3 Case study 2 – Spread foundations....................................................................................................................... 35 3.3.1 Introduction............................................................................................................................................................ 35 3.3.2 Data............................................................................................................................................................................ 35 3.3.3 Summary of the plans for supervision, inspection, monitoring and maintenance ........ 37 3.3.4 Supervision plan - comments ...................................................................................................................... 38 3.3.5 Inspection plan - comments ......................................................................................................................... 38 3.3.6 Monitoring plan – comments ....................................................................................................................... 39

3.3.7 Maintenance plan – comments................................................................................................................... 39 3.4 Case study 3 – Bored piles.......................................................................................................................................... 39 3.4.1 Introduction............................................................................................................................................................ 39 3.4.2 Basic determinations – quality management measures ............................................................. 40 3.4.2.1 Determinations and relevant clauses in the code ................................................................. 40 3.4.2.2 Comment....................................................................................................................................................... 41 3.4.3 Supervision and inspection plan – comments.................................................................................... 41 3.4.4 Monitoring and maintenance plans – comments ............................................................................. 42 3.5 Case study 4 – Anchors................................................................................................................................................. 42 3.5.1 Introduction............................................................................................................................................................ 42 3.5.2 Data............................................................................................................................................................................ 42 3.5.3 Plans........................................................................................................................................................................... 43 3.6 Case study 5 – Reinforced fill structures............................................................................................................ 44 3.6.1 Introduction............................................................................................................................................................ 44 3.6.2 Data............................................................................................................................................................................ 45 3.6.3 Supervision plan – comments ..................................................................................................................... 46 3.6.4 Supervision plan – comments ..................................................................................................................... 48 3.6.5 Monitoring and maintenance plan – comments ............................................................................... 48 3.7 Case study 6 – Rigid inclusions ................................................................................................................................ 49 3.7.1 Introduction............................................................................................................................................................ 49 3.7.2 Data............................................................................................................................................................................ 49 3.7.3 Supervision plan – comments ..................................................................................................................... 51 3.7.4 Inspection plan – comments ........................................................................................................................ 51 3.7.5 Monitoring plan – comments ....................................................................................................................... 52 3.7.6 Maintenance plan – comments................................................................................................................... 52 3.8 Case study 7 – Groundwater control..................................................................................................................... 52 3.8.1 Introduction............................................................................................................................................................ 52 3.8.2 Data – dewatering of an open excavation ........................................................................................... 52 3.8.2.1 Key design parameters ......................................................................................................................... 53 3.8.3 Checking for relevant execution standards ......................................................................................... 54 3.8.4 Supervision plan – comments ..................................................................................................................... 55

3.8.5 Inspection plan – comments ........................................................................................................................ 55 3.8.6 Monitoring plan – comments ....................................................................................................................... 56 3.8.7 Maintenance plan – comments................................................................................................................... 56 3.9 Checklists .............................................................................................................................................................................. 56 4 Acceptance criteria..................................................................................................................................................................... 57 4.1 General concept................................................................................................................................................................. 57 4.2 Setting limits ....................................................................................................................................................................... 58 4.3 Guidelines on contingency measures.................................................................................................................... 60 4.4 Case studies......................................................................................................................................................................... 61 4.4.1 Embedded retaining wall................................................................................................................................ 61 4.4.2 Soil nails and ground anchors ..................................................................................................................... 65 4.4.3 Embankments and cuttings .......................................................................................................................... 69 5 Implementation of Design and use of Execution Standards.............................................................................. 72 5.1 General ................................................................................................................................................................................... 72 5.2 Interaction between design and execution standards ................................................................................. 72 6 Conclusions..................................................................................................................................................................................... 73 References ............................................................................................................................................................................................. 74 List of abbreviations and definitions ...................................................................................................................................... 75 List of figures....................................................................................................................................................................................... 76 List of tables......................................................................................................................................................................................... 77 Annexes ................................................................................................................................................................................................... 78 Annex 1. Example checklists for plans............................................................................................................................ 78

Abstract EN 1997, also known as Eurocode 7, is the European standard for geotechnical design that provides the basis for the geotechnical aspects of building and civil engineering. The 2nd generation of EN1997 places a requirement on the designer to specifically address the implementation of their design as a part of the overall design process. The code lays out a series of plans which are to be produced by the designer to be used alongside the requirements of the execution standards. This guideline aims to provide the user with advice on the content to consider for these plans, with examples for different geotechnical structures. The guide indicates methods to align the design code requirements with the practical considerations of the execution phase of the project. EN1997 requires that the designer considers how the structure is to be checked during the service life and maintenance stage after actual construction is complete. The examples in this guide also cover how these requirements can be built into the plans that are specified as design output.

Foreword JRC Foreword The construction ecosystem is of strategic importance to the European Union (EU), as it delivers the buildings and infrastructures needed by the rest of the economy and society, having a direct impact on the safety of persons and the quality of citizens’ life. The construction ecosystem includes activities carried out during the whole lifecycle of buildings and infrastructures, namely design, construction, maintenance, refurbishment and demolition. The industrial construction ecosystem employs around 25 million people in the EU and provides an added value of EUR 1 158 billion (9.6% of the EU total)1,2,3. The construction ecosystem is a key element for the implementation of the European Single Market and many other important EU strategies and initiatives. The European Green Deal (COM(2019) 640 final) aims to achieve climate neutrality for Europe by 2050, and relies on numerous initiatives, noteworthy: — the New Circular Economy Action Plan (COM(2020) 98 final) and the New Industrial Strategy for Europe (COM(2020) 102 final) intending to accelerate the transition of the EU industry to a sustainable model based on the principles of circular economy; — the revision (COM(2022) 144 final) of the Construction Products Regulation (Regulation (EU) No 305/2011) aiming to enable the construction ecosystem’s contribution to meeting climate and sustainability goals and embrace the digital transformation of the built environment; — the New EU Strategy on Adaptation to Climate Change (COM (2021) 82 final) supported by the recent Commission Communication on managing climate risks (COM(2024) 91 final) that reinforces the need to address climate change concerns to guarantee resilience and sustainability of built structures and infrastructures and to ensure regular science-based risk assessments; — the first European Climate Risk Assessment (EUCRA) report which highlights the importance of EU policies for the built environment, including updating construction standards and related European datasets. Furthermore and recognizing that the EU's ambitions towards a climate neutral, resilient and circular economy cannot be delivered without leveraging the European standardization system, the European Commission presented a new Standardization Strategy (COM(2022) 31 final). The strategy spots standards as “the silent foundation of the EU Single Market and global competitiveness”. The EU has put in place a comprehensive legislative and regulatory framework for the construction sector, including European standards (EN). Within this framework, the Eurocodes are a series of 10 European standards, EN 1990 to EN 1999, providing common technical rules for the design of buildings and other civil engineering works. In fact, the Commission Communication on managing 1 Commission staff working document: Scenarios for a transition pathway for a resilient, greener and more digital construction ecosystem (https://ec.europa.eu/docsroom/documents/47996) 2 Council of the EU, Press release 30 June 2023, https://www.consilium.europa.eu/en/press/pressreleases/2023/06/30/council-adopts-position-on-the-construction-products-regulation/ 3 Transition Pathway For Construction, European Commission, DG GROW, https://ec.europa.eu/docsroom/documents/53854

climate risks directly mentions the Eurocodes, highlighting the role of building and infrastructure standards in integrating climate adaptation and resilience. The Commission Recommendation 2003/887/EC on the implementation and use of the Eurocodes for construction works and structural construction products recommends undertaking research to facilitate the integration into the Eurocodes of the latest developments in scientific and technological knowledge. In this context, the so-called second generation of the Eurocodes is under development under Mandate M/515 and expected to be available by 2026. The second generation Eurocodes incorporates improvements to the existing standards and extends their scope by embracing new methods, new materials, and new regulatory and market requirements, including considerations for climate change impact on structural design. In order to support the implementation of the second generation EN 1997 “Geotechnical Design”, CEN Technical Committee 250/Sub-Committee 7 (TC250/SC7) produced a series of guidelines addressing the most important new aspects in the standard. The series of guidelines contains the following documents: — Guideline C1 – “Determination of representative values from derived values for verification of limit states with EN 1997” — Guideline C2 – “Assembling the Ground model and the derived values” — Guideline C3 – “Reliability-based verification of limit states for geotechnical structures” — Guideline C4 – “Implementation of design in execution and service life” Within the framework of Administrative Arrangements between the European Commission’s Joint Research Centre (JRC) and DG GROW on support to policies and standards for the construction ecosystem, JRC is engaged in activities facilitating the implementation and practical use of the second generation Eurocodes. In this context, the guidelines by TC250/SC7 are published as JRC technical reports, part of the series “Support to the implementation, harmonization and further development of the Eurocodes”. We hope that this report will provide a sound and helpful basis for the implementation and use of the second generation EN 1997 “Geotechnical Design” and contribute to training and education of the professionals engaged in geotechnical design, supporting further skills development for individuals' careers and also EU's competitiveness. The report is available to download from the “Eurocodes: Building the future” website (http://eurocodes.jrc.ec.europa.eu). The authors have sought to present useful and consistent information in this report. However, users of the information contained in this report must assess if such information is suitable for their purposes. Ispra, September 2024 François Augendre, Head of Unit Georgios Tsionis, Deputy Head of Unit E. 3 Built Environment Unit Directorate E – Societal Resilience and Security Joint Research Centre (JRC) European Commission

SC7 Foreword With the adoption of the 2nd Generation of EN1997 – Geotechnical design - Member States will need to implement new procedures in many different topics, not considered in the first generation of the Code such as the assessment of Representative values, the Ground Model, the use of Reliability methods and the implementation of design in the execution phase. To facilitate the implementation of EN1997, CEN Technical Committee 250/Sub-Committee 7 (TC250/SC7) therefore decided to produce a suite of Guidelines, one for each of the most relevant new aspects, to help ensure that the objectives of the code writers are reached in practice. According to Clause 4 of EN1997, Basis of design, the fundamental step to ensure that the prescribed reliability in geotechnical design is reached, is the development of a representative Geotechnical Design Model being the combination of the Ground Model and the set of design values of relevant geotechnical properties needed for verifications. The first Guideline of the suite addresses the fundamental process of determining design values of geotechnical properties from derived values, obtained from a variety of activities of the ground investigation. Once the representative values of properties, either characteristic (through statistical evaluation) or nominal (cautious estimate), are determined, design values are obtained by applying the partial factors for a design situation. The process of assembling the Ground Model is addressed in the second Guideline, where the importance of the progressive upgrading of the Model with an increase of knowledge of the ground within the Zone of Influence of the specific structure is highlighted. The concept of the Zone of Influence in the second generation of EN1997 has been widened so that environmental and seismic aspects have become more central in planning the Ground Investigation and processing the results. A significant novel aspect is the use of EN1997 in combination with reliability-based methods. This is likely to lead to a very important evolution of safety assessments in geotechnical design in the coming years. EN1997 like other Eurocodes is fundamentally reliability-based although safety verifications are tied to the application of partial factors. However, in the second generation of EN1997, Clause 4 explicitly states that reliability-based design is only one of the options to verify limit states in geotechnical design. As these methods are not usually addressed in most of the teaching programs, it has been decided to dedicate a specific guideline to reliability-based verification of limit states that is consistent with the safety concepts of the Eurocodes. Moreover, the objective of this third Guideline is to provide information for code developers to perform reliability calibration of partial factors given the preparation of National Annexes. It is well known by geotechnical designers that a great contribution to the reliability of a geotechnical construction relies upon its execution and its real performance. This is why EN1997 now specifically dedicates a full clause in EN 1997-1 to the implementation of design during execution and service life. The fourth Guideline presents measures to ensure that the design is correctly implemented in the different construction phases and how to document the activities carried out to this scope on the construction site. After a general description of the suggested rules and methods, the guideline describes good practice for establishing a Supervision Plan, Inspection Plan, Monitoring Plan and Maintenance Plan, how to establish acceptance criteria and limit values and gives contingency measures that might be utilized when an acceptance criterion/limit value is reached. This is implemented for typical geotechnical constructions such as embankments, bored piles, rigid inclusions, and groundwater control. The upgrading of EN1997 to the methods of modern Geotechnics was a very difficult task that has been achieved thanks to the strong involvement of many dedicated people from all European

countries. However, this process cannot be considered concluded with the publication of the new Eurocode documents alone and there will be a long route to implementing EN1997 into the engineering practices of the many countries involved. The involvement of the many members of the Task Group C1 to C4 of SC7, who prepared these Guidelines is very gratefully acknowledged. These Task Groups have performed tremendous work over almost 4 years to compile knowledge and experience in European geotechnical engineering to draft these Guidelines. It is therefore strongly believed that for the transition from the 1st to the 2nd Generation of EN1997, these Guidelines will be very helpful in clarifying the new concepts and methods. The Guidelines will also provide didactic background material that could not be presented in the Code. Giuseppe Scarpelli, Coordinator Task Group C1 to C4 Adriaan van Seters, Chairman CEN/TC250/SC7 “Geotechnical Design”

Acknowledgements This guideline has been prepared by Task Group C4 within TC250/SC7/WG1 as a result of European cooperation. Member countries in Task Group C4 have been Cyprus, Germany, Finland, France, Latvia, Netherlands, Norway, Poland, Romania, Switzerland, Sweden and the United Kingdom. The full list of members is: Bartho Admiraal, Romāns Arhipenko, Suradj Bhagirath, Niklas Blomqvist, Witold Bogusz, Björn Böhle, Christopher Caplane, Anna-Maria Edvardsson, Astri Eggen, Gaël Gourrin, Tommi Hakanen, David Hard, Klaus Idda, Peter Ingram, Piotr Kanty, Anurag Kushwaha, Nicolas Nayrand, Krishna Panthi, Panicos Papadopoulos, Heikki Saarikivi, Oliver Sand, Panu Tolla, George Tsisas, Veli-Matti Uotinen, Roderik D. van der Kamp, Simon van Dijk, Hansjörg Vogt. The guideline has been reviewed by members of the management group within SC7. Authors Witold Bogusz, Instytut Techniki Budowlanej, Warsaw, Poland Christopher Caplane, Groupe Fondasol, Biarritz, France David Hard, Bachy Soletanche Ltd, Camberley, United Kingdom Klaus Idda, BAUER Design Gmbh, Schrobenhausen, Germany Peter Ingram, Arup, London, United Kingdom Piotr Kanty, Menard Polska Sp. Z O.o., Warsaw, Poland Anurag Kushwaha, Atkins Réalis, Epsom, United Kingdom Nicolas Nayrand, Bureau Veritas Construction, Courbevoie, France Oliver Sand, Zentrale Technick, Köln, Germany Francesca Sciarretta, Joint Research Centre (JRC) of the European Commission, Ispra, Italy George Tsitsas, Romanian Society for Soil Mechanics and Geotechnical Engineering, Bucarest, Romania Hansjoerg Vogt, Tragweite AG, Vaduz, Liechtenstein Editor David Hard, Bachy Soletanche Ltd, Camberley, United Kingdom

1 Introduction 1.1 Context The design and performance of a geotechnical structure is directly linked to the method of construction, and the quality of the execution. As a result, it is important that the assumptions and requirements of the design are properly communicated through to the execution team, and onwards into the service life of the structure. Further, it should be noted that the expression “designer” does not only address the “classic” design portion by a geotechnical or structural designer, but any party or person that is involved in the preparation of the envisaged construction process – for example, work preparation, scheduling, site manager etc. The aforementioned “classic” design portion of the process is covered by EN1997, and there are accompanying execution standards for different techniques to cover the construction phase. These documents are complementary but exist in parallel to each other. The new generation of EN1997 now stipulates that the execution process and service life are specifically addressed at the design stage, which requires linking the two sets of documents in a way that was not always previously addressed. This document is intended to provide guidance alongside, and a link between, the formal CEN design and execution standards. 1.2 Objectives This document has been written to address specific points identified by the CEN TC250/SC7 management committee as needing further clarification and guidance to allow the users to meet the requirements of the code. These points are: — general guidelines on the implementation of the design during execution — guidelines on good practice for establishing a Supervision Plan, Inspection Plan, Monitoring Plan and Maintenance Plan as required in the next generation code — guidelines on establishing acceptance criteria and limit values — guidelines on contingency measures that might be utilized when an acceptance criterion/limit value is reached. 1.3 Target audience The target audience for this guideline is predominantly: — Practitioners designing geotechnical structures — Contractors carrying out the execution of geotechnical structures, to their own design or that of others. As the design code requirements extend beyond execution and into the service life of the structure, there are aspects that will also be of interest to the final owner/operator.

1.4 Scope There is a mandatory requirement set out in EN1997-1, cl. 10.1 for the design to include specifications and plans to allow the implementation for the design to be correctly managed during execution and the design service life. The nature of the code means that it cannot include examples or guidance on how this requirement is to be met. This document is intended to help users address the requirements of this design clause. [EN 1997-1 cl. 10.1: (1) <REQ> The design of a geotechnical structure shall include specifications for supervision, inspection, monitoring, and maintenance to check implementation of the design during execution and design service life.] These guidelines have been written to be applicable to all scales of geotechnical project, be it GC1 or GC3. As with all geotechnical design, the application of the advice requires judgement to suit specific site ground conditions and cannot cover all situations in detail. [EN 1997-1 cl. 4.1.2.3 Geotechnical Category] 1.5 Application of this guide In principle, this guide is applicable to all design phases in a project. Although a successful “Implementation of design” can of course only be proven once execution has started, it is essential to understand that the basis for such is laid from the project beginning, or, vice versa, it is difficult to overcome shortcomings from earlier design stages during detailed design or even execution. Examples supplied are not exhaustive and engineering judgement will be required to apply them to any specific project, especially in complicated situations (geometry, ground conditions, location, etc).

2 Implementation of design in execution 2.1 General aspects of successful “implementation of design in execution” The following factors have been identified as key for a specific project: 1. Common understanding of terms (refer to chapter 2.2) 2. Common understanding of project phases (refer to chapter 2.3) 3. Common understanding of roles and responsibilities (refer to chapter 2.4) 4. Common understanding of key design factors and risks (refer to chapter 2.5) 5. Common understanding of effective communication (refer to chapter 2.6) 6. Common understanding of good and transparent documentation (refer to chapter 2.7) 2.2 Definition of terms The following terms and definitions have been elaborated within this report, above those already supplied within the code. These are for clarification and are not meant to replace the code definitions: 2.2.1 Supervision Supervision is an act or instance of directing, managing, or oversight and comprises all measures or activities during execution to check and ensure that the construction work is carried out by personnel having appropriate skill and experience and follows the process, including execution methods and construction stages, set by the execution specification. Note: As a minimum, supervision is conducted by the party executing the respective process (e.g. the Designer supervises the design process, the Contractor supervises the construction process). The responsibilities for any additional supervision activities should be specified by the relevant authorities or, where not specified, agreed for a specific project, by the relevant parties. (Definition according EN 1997-1 cl. 3.1.9.4 supervision: “measures or activities during execution to check that the construction work follows the process, including execution methods and construction stages, set by the execution specification”.) 2.2.2 Inspection An inspection is an organized examination or formal evaluation exercise and comprises measures or activities during execution to check the compliance of the execution with the execution specification and the validity of the design assumptions in relation to encountered ground conditions at the site. Inspection is understood to mean checking the material and product properties, ground conditions, dimensions and quality. Note: As a minimum, inspection is conducted by the party providing the material or product (e.g. the Designer inspects the design report, the Contractor inspects the construction product). The responsibilities for any additional inspection activities should be specified by the relevant authorities or, where not specified, agreed for a specific project, by the relevant parties.

(Definition according EN 1997-.1 cl. 3.1.9.5 inspection: “measures or activities during execution to check the compliance of the execution with the execution specification and the validity of the design assumptions in relation to encountered ground conditions at the site”.) 2.2.3 Monitoring Measuring/observing the behaviour of the ground and/or structure, during execution and / or design service life, to check compliance with the anticipated behaviour defined by a set of threshold values and determined by calculation or engineering judgement. Note: The responsibilities for monitoring activities should be specified by the relevant authorities or, where not specified, agreed for a specific project, by the relevant parties. (Definition according EN 1997-1 cl. 3.1.9.6 monitoring: “measuring / observation of the behaviour of the ground and/or structure, to check compliance with the serviceability criteria”.) 2.2.4 Maintenance Set of activities performed during the service life of the structure so that it fulfils the requirements for reliability. Note: The responsibilities for maintenance are typically with the owner of the structure, unless specified otherwise by the relevant authorities or agreed for a specific project, by the relevant parties. (No definition available for maintenance in EN 1997-1). 2.2.5 Execution specification Set of documentation, typically prepared by several parties, necessary for the execution of a project. As outlined in EN 1997-1 C4.1, the geotechnical designer’s contribution to the execution specification forms part of the Geotechnical Design Report. Note: The responsibilities for the contribution to the execution specification, as well as the continuous update and distribution of the content list and revision control, should be specified by the relevant authorities or, where not specified, agreed for a specific project, by the relevant parties. (Definition according EN 1997-1 cl. 3.1.9.7 execution specification: “set of documents covering all drawings, technical data and requirements necessary for the execution of a particular project Note: The execution specification is not one document but signifies the total sum of documents required for the execution of the project. It includes the project specification prepared to supplement and qualify the requirements of the European Standards, as well as referring to the national provisions relevant in the place of use.”). Note: EN 1997-1 allows any format for the execution specification. However, unless there are specific requirements to do it another way, it is recommended to focus on drawings for all design-related information for the execution specification. It is further recommended to set up, continuously update and communicate an overview content list for all elements forming a project’s execution specification, including revision control. 2.2.6 Designer A designer is one or multiple persons or parties planning a physical structure during a time period before it is erected, by preparing static calculations, drawings, plans, method statements or other contributions to the execution specification. The geotechnical designer, in this report, is the person(s) or party preparing the geotechnical design calculations for a project.

Note: “Designer” must therefore not be understood automatically as “the geotechnical / structural designer” (conducting the geotechnical or structural design calculations) solely. It can also be the scheduler, the work preparer, or anybody else providing input to the execution specification. 2.3 Definition of project phases A project typically follows a couple of phases from the initial project idea until its decommissioning. The organisation of any given project is specific. It depends, amongst other things, on influences such as the Client requirements and national legislation. In order to understand the development of all design-related as well as execution-related documentation and the dependencies during these phases, it is firstly necessary to define the wording of these phases. For this report, the UK-based RIBA stages are used as a basis, while other countries use other phases, e.g. in Germany the HOAI-phases. Table 1 gives an international comparison of these stages: (RIBA = Royal Institute of British Architects, see https://www.architecture.com and HOAI = Honorarordnung für Architekten und Ingenieure, see https://www.hoai.de )

Table 1. Comparison of international plans of work

RIBA (UK) ACE (Europe)

Pre-Design 0 Strategic Definition 0 Initiative

AIA (USA)

NOT USED

APM (Global)

0 Strategy

Spain

NOT USED

NATSPEC (Aus)

NOT USED

1 Preparation and Brief 1 Initiation NOT USED 1 Outcome Definition NOT USED Establishment

NZCIC (NZ) HOAI (DE) South Africa

NOT USED

Pre-Design

1 Grundlagenermi ttlung Basic determination NOT USED

2 Vorplanung Pre- Design 1 NOT USED

Source: Developed by the Authors

Design 2 Concept Design

NOT USED

2.1 Concept Design Schematic design 2 Feasibility

2.2 Preliminary Design NOT USED NOT USED

Proyecto Basico Concept Design

NOT USED Schematic Design

3 Developed Design 2.3 Developed Design Design Development 3 Concept Design NOT USED Design Development

Concept Design 3 Entwurfsplanun g Concept Design 2 AGR Stage

Preliminary Design 4 Genehmigun gsplanung 3 Stage P

Developed Design 5 Tender Stage

4 Technical Design 2.4 Detailed Design Construction Documents 4 Detailed Design Proyecto de Ejecucion Contract Documentati on Detailed Design 6 4 Construction Documents

Construction 5 Construction 3 Construction Construction 5 Delivery Direccion de Obra Construction Construct

Handover 6 Handover & Close Out NOT USED

In Use 7 In Use 4 Building Use

End of Life NOT USED 5 End of Life

NOT USED

NOT USED NOT USED

6 Project Close Final de Obra

7 Benefits Realisation NOT USED

NOT USED NOT USED

NOT USED NOT USED

- Facility Manageme nt - Operate

NOT USED NOT USED

NOT USED

5 Construction

NOT USED

NOT USED NOT USED

The measures discussed under EN 1997-1 cl. 10 Implementation of design can have relevance from the start of RIBA stage 1 (starting with the initial site surveys) until the end of RIBA stage 7 (with the end of any maintenance measures for the structure). Figure 1. RIBA Stages and potential relevance of EN1997-1 cl.10.1 Implementation of Design “Implementation of design“

Source: RIBA Plan of Work 2020

© RIBA 2020

In Figure 2, the project phasing sequence including the preparation of documents for a “typical” project is shown. What becomes obvious is that specific activities are repeated, and the scope and depth of investigation becomes more and more detailed with the progression of the project through the project phases. It should be considered a standard procedure that at the transition from one phase to the other, all activities from the previous phase are revised (cross-discipline) for consistency. This is also convenient because parties to the contract often join or leave a project at these transition points.

2.4 Roles and responsibilities

2.4.1 Roles and responsibilities: General It is not in the remit of EN1997 to define contractual responsibilities, however it is essential that all roles and responsibilities are identified in a project, and that all parties and individuals involved have the same understanding of those and of their own areas of responsibility. This is especially important when roles, responsibilities or parties change during the project phases (scheduled or unscheduled) – in that case, it is of utmost importance to define: — which roles, responsibilities or parties change or leave the project team — what is the degree of completion / fulfilment at the key date of change or handover — by whom and at which key date the affected roles or responsibilities are taken over — when and how work results are handed over, and how this is documented — if and to which extent work results which are taken over remain within the responsibility of the preceding party/person or the follow-on party/person, and — if and to which extent work results require a (documented) check by the party/person handing over and or the party/person taking over.

Figure 2. Project phasing sequence including the preparation of documents for a “typical” project Source: Developed by the Authors 18

2.4.2 Roles and responsibilities: typical roles The following roles are considered “typical” in this report: — The Project Owner – usually one party (or consortium of several parties acting as one for the project) that typically orders, pays and finally owns the project — The Architect - usually one party (or consortium of several parties acting as one for the project) that define the position, the inner geometries and main properties of the Project, typically having a contract with the Project Owner — The Contractor(s) – one or several parties responsible for the execution of (parts of) the works, having a contract with the Project Owner, possibly contracting with own subcontractors for portions of their work. — The Designer(s) – one or several parties responsible for the design of (parts of) the works, having a contract with the Project Owner or one of the Contractors. Note that in the sense of 2.2.6. the Contractor or other parties can also play a role as a “designer” for a project. — The Subcontractor(s) - one or several parties responsible for specific specialist works e.g. site investigations, enabling or demolition works. 2.4.3 Checklist proposal As outlined in the previous subchapters, roles and responsibilities should be identified as projectspecific, unless defined by the relevant authorities. The attached Checklist can help to get and keep an overview over the roles and responsibilities applicable in a specific project. Figure 3. Checklist for Implementation of Design related to project stage

Source: Developed by the Authors 2.5 Key design factors and risks In the process of design and its implementation at the construction stage, some of the obtained or assumed information can have a critical role for successful execution and ensuring the specified level of reliability. Such key design factors, as well as all design assumptions, should be presented in a transparent way, allowing for independent review of the project as well as for comparison with real conditions encountered on the site. Successful implementation of design in execution requires the Contractor, potentially lacking the relevant (geotechnical) design knowledge, to be able to judge whether they are still working within the assumptions of the design and when falling outside of them. Early identification of potential problems is the most reliable way to ensure timely reaction and implementation of appropriate remediation measures. However, it is the role of the Designer to assess which design factors are: — critical, — highly significant, — just relevant, or — not relevant to execution phase. in the context of designed structure and considered limit states. The Designer should then assess what information is needed to be passed to the execution team, and which items should be controlled through the use of the required plans. At all times clarity of communication and relevance should be the key factors in deciding what information from the design needs to be passed over. The list below comprises the list of common key design factors that normally need to be considered by the designer in sufficient detail, and if needed, verified at the execution stage. 2.5.1 Code references and tolerances The documentation prepared for the execution specification of a project must clearly state reference to relevant execution codes, state the allowable tolerances and other important conditions of execution. Note: When tolerances are considered according to the relevant execution standards, reference to the latter can be considered sufficient.

2.5.2 Soil and rock stratification Assumption of stratification of soil or rock mass is of importance for all types of geotechnical structures. Therefore, the documentation prepared for execution of the works must show the assumed soil / rock stratification, typically in cross sections, and preferably in relation to the designed structural elements or other relevant information (e.g. planned excavation levels). Note: Those assumptions are commonly presented in the ground model and developed further in the geotechnical design model, but basic information should also appear in the execution drawings. Where variation in stratification may significantly affect the expected behaviour of a geotechnical structure, the uncertainty in the design assumptions should be carefully considered and emphasized. For highly complex ground conditions and geotechnical structures, development of a 3D ground model might be advisable. Note: As an example, a remark “grout body of anchor to be fully embedded in sand layer” clarifies that potentially the free anchor length may need to be extended to match actual conditions encountered. 2.5.3 Soil and rock parameters Geotechnical properties, parameters and characteristic of a soil or a rock mass are commonly considered as the main design assumptions. The geotechnical designer documents the considered geotechnical properties in the defined geotechnical design model. Where appropriate, e.g. for refill or compaction areas, target values for such parameters should be specified on the execution drawings. It is generally advised to also specify expected ranges of variations of the most significant parameters, at least in qualitative manner. Note: Uncertainty behind the adopted values of ground properties can be often as important as the adopted design values themselves. It is a good practice to inform the execution team of what variation from the baseline assumption is still considered as acceptable by the designer. 2.5.4 Groundwater and assumed groundwater lowering levels The consideration of groundwater should include not only its current levels, but also how they may (or shall) change in the process of construction or how they might vary with time and seasonal variations. Again, the documentation prepared for execution of the works must show the groundwater levels and possible variations, typically in cross sections. Note: This is especially important for geotechnical structures at waterfronts and in marine environments. Potential impact of climate change should also be considered. 2.5.5 Adjacent assets, structures and utilities When adjacent structures are located within the zone of influence, the effect of the new structure on these existing ones should be investigated and evaluated. Assumed geometries of adjacent structures should be shown on the execution drawings and allowable serviceability limits (e.g. settlement, inclination, noise, vibration) should be defined, as applicable.

2.5.6 Contamination of soils and water In addition to important environmental aspects of possible contamination of the soils and water at the site, the presence of contaminants usually is a key design factor in terms of durability of structural elements and materials (e.g. steel, concrete). Note: Durability of a structure in long-term conditions might be highly dependent on aggressiveness of the environment. Design for durability is as important as verification of other limit states. 2.5.7 Permanent and temporary traffic loads assumed In addition to any permanent loads affecting the behaviour of the structure, any live loads resulting from traffic (e.g. roads, trains, trams) or construction activities (e.g. construction machinery, cranes) should be considered as a key design factor and must therefore be defined in the execution documentation. Possible load restrictions and exclusion zones should also be clearly stated and included in the maintenance plan. Note: Ideally, it should be specified for what kind of traffic the load is representative (e.g. allowable weight of construction machinery). Simple presentation of the surcharge adopted in the design might not be sufficiently informative for the contractor and people working at the site. 2.5.8 Design lifetime, construction stages and their assumed maximum durations In geotechnical engineering, many phenomena are time-dependent in nature. This imposes some restrictions on how some design assumptions should be made in the context of design lifetime of the structure. Furthermore, the order and duration of construction stages will often be important and they should be specified by the Designer when relevant. Note: When some level of degradation can be expected (e.g. corrosion of a sheet pile wall) over the design lifetime, such scenario should be included in the design analysis. 2.6 Effective communication and documentation An effective and transparent communication between the project parties, as well as a good documentation system, and management of design, design interfaces, communication, etc., is key for project success. Therefore, “communication rules and lines” should be agreed and documented such that new parties or persons joining the project can find their way. Generally, communication should be conducted pro-actively from all parties, i.e. there is an obligation to both fetch and to bring information. The following sections highlight recommendations for how this should be related to the “Implementation of Design”. 2.6.1 Installation of regular communication lines It is recommended that all projects: — Setup and maintain an organizational chart with a contact list including roles and responsibilities.

— Setup and maintain a task list with due dates and responsibilities. — Setup and continuously update the content list of the execution specification. Additionally, for GC2 and GC3 projects: — Setup regular meetings, e.g. on a weekly basis. Such meetings could also be the place to announce and briefly discuss the content and extent of any upcoming document revisions. — Notes should be taken from the meetings and action lists updated and regularly reviewed. A person to take these notes and manage the action lists shall be clearly identified at the outset. — Document and interface management must be defined from project inception, with clear guidelines on how to deal with revisions and distribution of documents. — Define a “core team” from the various parties involved which discusses progress and important issues in short regular intervals and then forwards important information internally within their party. This core team can also play an important role for the handling of errors and omissions detected during the project. — Setup a “Design Handover Meeting” between all parties between design stages or at the transition from design to execution.  The first involved party then wraps up the basic conditions, parameters and design developments and decisions and explains their contribution to the execution specification. It should be highlighted by the designers both what has been done by them, and what has NOT been done by them, and what the expectations are regarding content and timeline of contributions from other parties.  Similarly, the second party / parties should describe their understanding of their project participation, interfaces to other parties, as well as their contribution of content and timeline to the execution specification. — The installation of a design coordination person or even design coordination group has been proven to be beneficial. Note: The design coordinator’s task is to make sure that quality, completeness (including interfaces) and in-time availability of design comply with the project requirements. Typically, regularly scheduled meetings with notes and followups form the basis of such design coordination. 2.6.2 Interface coordination Interface coordination between any parties and / or stakeholders involved can form an essential part of the design coordinator’s work (a separate interface manager may be appropriate for larger projects with complex interfaces). Note: Interface agreements should be considered as a form of communication and therefore should follow the same communication rules (transparency, documentation). 2.6.3 Dealing with errors and omissions In case of errors, omissions, or the like, it is of special importance to inform all related parties as soon as possible and thoroughly, in order to then define the extent / the limits of such defects and immediately define responsibilities and timelines of associated updates of design and execution of the works.

Note: The “core team” as mentioned in bullet point “Installation of regular communication lines” above could be first point of contact for such cases. 2.6.4 Dealing with change requests In the event of changes, a change request shall be raised to notify relevant stakeholders of the affected scope of work. Discussion on the change shall be reviewed, discussed, and agreed upon between the design and execution teams. During this process, the effects on scope, responsibilities, budget, and timeline shall be defined and agreed upon. (a separate change control team may be appropriate for larger projects). Note: The changes should be properly documented and followed during the execution phase. The design coordinator should ensure that the approved changes are complied with through progressive meetings. 2.6.5 Design quality The execution relies principally on drawings and model representations (including 3D BIM models), and less on written information such as statements, reports etc. Ideally it should be the aim to collect all information required for the execution of the works on a set of drawings solely. This decreases the chance that an important piece of information will be omitted during the construction. Note: Where this document refers to “drawings” these can be replaced by digital data in 3D models etc. In such case the ability to locate and retrieve the required information becomes even more critical. The design should be of good quality, this applies in particular to the drawings produced for execution. As already addressed in chapter 2.5 of this report, such drawings can and should comprise information about the Designer’s assumptions and decisions in a way that it can be crosschecked directly on site, without the need for excessive processing and interpretation of the acquired information. Examples are: — Assumed temporary and permanent groundwater levels; — Assumed stratigraphy and main parameters of soils; — Assumed construction staging; — Assumed traffic loads during construction; — Assumed maximum design loadings; — Defined exclusion zones; — Defined threshold values for monitoring; — Information about utilities and structures in the vicinity of the works; — Extent of “Zone of influence”; — Assumed GCC, GC, CC; — Assumed tolerances; — Agreed interfaces; — Reference to execution codes.

— Reference to other scope of work not covered within the drawing. The execution detail should be such that (cost / design) responsibility for undesigned sections is not shifted to other parties, e.g. the Contractor, without their prior agreement. This applies e.g. for temporary slopes. Preferably, all major risks should be eliminated or reduced at the design stage. Ideally, during the design phase, the designer should eliminate and/or reduce the foreseeable risks to as low a level as reasonably practicable (ALARP priniciple). Any residual risks that need to be passed on to the Contractor during the execution phase should be documented in a risk assessment form. The assessment should include details of the significant risks and what actions have been considered necessary to be taken to control the foreseeable risks. The Contractor should always be informed about these risks with full transparency. 2.7 Further guidance 2.7.1 The use of National Specifications Numerous national guidance documents are available to assist in the clear presentation of construction information. These include for example: — The ICE Specification for Piling and Embedded Retaining Walls Third Edition (2017) — The ICE UK Specification for Ground Investigation Third Edition (2022) — ZTV-ING “Zusätzliche Technische Vorschriften und Richtlinien für Ingenieurbauwerke, Part 1

Section 2 „Technische Bearbeitung“

2.7.2 Geotechnical Baseline Reports (GBR) Ground conditions influence every aspect of construction, and unforeseen ground conditions can pose a significant risk to a project. Construction costs are often heavily influenced by the pricing of risk, and the purpose of a GBR is to set the range of expected conditions, and ownership of risk so that for example, the Contractor can reduce their contingency allowances. GBR statements are therefore not necessarily geotechnical fact but represent an agreed position. The GBR is therefore a contractual document - rather than a design document. This defines a requirement for Contract documentation to include ground reference conditions prepared for or on behalf of the client. It is essentially a set of statements about the nature of the ground and groundwater, which define the range of expected ground conditions and establish a basis for applying the contract, where conditions encountered during construction are materially different. Note: GBRs emerged in the US in the early to mid 90s, but in the UK started being used on major infrastructure projects in the early 2000s. At a similar time to the “The Joint Code of Practice for Risk Management of Tunnel Works in the UK” (2003), a guidance document published by the Association of British Insurers and the British Tunnelling Society to set out best practice for managing risk in tunnelling and underground works.

3 Establishing Plans 3.1 General concepts 3.1.1 Introduction The aim of having a guide on implementation of the design in executions is to help describe the link between them. As the codes highlight the need to base the design on the quality management system described in them, the implementation of the design in execution is one part of it. In order to ensure the necessary level of reliability, there is a requirement in the code to create a series of documents: inspection plan, supervision plan, monitoring plan and maintenance plan. There is nothing in the code to describe how to form these plans, so these guidelines are intended to be a source of ideas. These plans must be part of the geotechnical design report (GDR) but there are no limitations on how it should be done. They could be implemented as chapters, or they could be appendices. At the same time, it is possible to merge them together if the specific case requires it. For example, it might be hard to separate supervision and inspection in some cases, in which case it would be practical to merge the two plans. There are also cases when one type of plan may not be applicable, for example monitoring plans where monitoring is not needed and so the plan does not exist. In such cases, the omittance of a plan should be justified. To identify the content of each plan, the definitions of supervision, inspection, monitoring and maintenance are crucial. They are cited and commented on in 2.2.1- 2.2.4 of this document. The link between design based on EN1997 and the execution is not always clear. It is further complicated by the interaction with the execution standards, which in many cases refer to design aspects. At the same time there are a set of laboratory and field tests standards, the set of standards describing the monitoring requirements, specifications and other documents in between design and execution. The aim of having these plans required by the design codes, is to highlight what is crucial from the design point of view and to ensure it is incorporated properly in the execution and quality checks. There might be parameters, factors, elements on which the design is based, and they need to be checked during execution to confirm / validate the design, and to easily and in a timely manner identify where the execution potentially deviates from the design assumptions. 3.1.2 Links to standards Table 2 shows standards which are used in more than one specific geotechnical structure. These “general” standards include information about supervision, inspection, monitoring and maintenance. The table is to help in the selection of the appropriate standard content when dealing with one of the four plans.

Table 2. Comparison of international plans of work Code or Guideline

Supervision Inspection Monitoring Maintenance General Aspects

EN1990 Basis of structural and geotechnical design

x

x

EN1997-1 Geotechnical design - Part 1: General rules

x

x

x

x

x

EN1997-3 Geotechnical design - Part 3: Geotechnical structures

x

x

x

x

EN ISO18674-2 Geotechnical investigation and testing – Geotechnical monitoring by field instrumentation. Part 2 Measurement of displacement across a line: extensometers

x

x

EN ISO18674-3 Geotechnical investigation and testing – Geotechnical monitoring by field instrumentation. Part 3 Measurement of displacement across a line: inclinometers

x

x

EN ISO18674-4 Geotechnical investigation and testing – Geotechnical monitoring by field instrumentation. Part 4 Measurement of pore water pressure: piezometers

x

x

EN ISO18674-5 Geotechnical investigation and testing – Geotechnical monitoring by field instrumentation. Part 5 Stress change measurements by total pressure cells (TPC)

x

x

Source: Developed by the Authors

3.1.3 Terms The definition of terms related to supervision, inspection, monitoring and maintenance is described in points 2.2.1- 2.2.4 where additional comments are to be found. A particular point to highlight and clarify is the difference between supervision and inspection: – supervision is related to the technological process like performing ground improvement, boring piles, building an embankment, etc., inspection is related to materials and products properties like concrete parameters, geometry etc. Inspection covers also the ground model and ground conditions verification. However, the difference will not always be clear and easy to understand. In such cases the key point is to ensure that the required design aspects are picked up and verified through the plans, rather than overly focussing on which plan the point is to be covered in. According to EN19971 and EN1997-3 the specified plans must be prepared but there are not requirements as to whether those must be four independent plans (documents) or if everything can be included in one document or even part of a document. This will depend on the geotechnical structure and the ease of use of the document. To some extent it can also be effected by national practices and guidance documents.

3.2 Case study 1 – Embankment

3.2.1 Introduction When designing geotechnical structures comprising of slopes, cuttings and embankments there are two main sets of standards that need to be considered together: EN1997 and EN16907. The first one deals with geotechnics, the second one with organization of earthworks projects (including cutting and embankments) and their planning. In both there are references to each other and both contain information that is useful while preparing inspection, supervision and monitoring plans. Within the zone of influence of the geotechnical structure there are several elements to be looked at: subsoil to the identified depth, nearby structures, other geotechnical structures or slopes, and the cutting or embankment itself. The aim of this example is to show how to prepare plans for a typical simple embankment with no or very low number of adjacent assets. Soft soils are nowadays also typical ground conditions under this type of structure. The example focuses only on the requirements for embankments, which should be widely known, but at the same time highlights some important aspects in terms of ground model verification and monitoring. Table 3 shows standards related to each case.

Table 3. Links to specific standards

Code or Guideline

Implementation of design – regulations for

Supervision Inspection Monitoring Maintenanc e General Aspects

EN16907-1. Earthworks – Part 1: Principles and general rules

x

x

x

x

x

EN16907-2. Earthworks – Part 2: Classification of materials

x

x

EN16907-3. Earthworks – Part 3: Construction procedures

x

x

EN16907-4. Earthworks – Part 4: Soil treatment with lime

x

x

x

and/or hydraulic binders

EN16907-5. Earthworks – Part 5: Quality control

x

x

x

Source: Developed by the Authors

3.2.2 Data — Soil / rock stratification: very soft clay thickness 3-7m, medium sand till the depth of influence. — Embankment material parameters assumed: medium sand c’=0kPa, F’=40o, g=18kN/m3, E=100MPa at 100kPa reference stress. — Permanent traffic loads assumed as 12kPa, no temporary traffic loads assumed.

— Construction stages: embankment layers 13 x 0.4m + road layers 0.8m. No maximum time constraints; minimum time constraints relating to consolidation of the subsoil. — Geotechnical category was chosen as GC2. — Geometry presented in figure 4. Figure 4. Case study 1 cross section

Source: Developed by the Authors

3.2.3 Summary of plans for supervision, inspection, monitoring and maintenance The aspects considered in this guide as the most significant and needing to be addressed in the plans are listed in Table 4 and Table 5. Note: Where specific values are given they are related to this particular case study. Equivalent values for another project need to be evaluated on the specifics of that situation.

Table 4. Information relevant for Supervision and Inspection

Parameter Soil group for the first embankment layer (foundation base) Soil group for the remainder of the embankment layers (core, fill) Other embankment material characteristics Friction angle, appropriate modulus of the soil In situ density testing, stiffness and bearing capacity testing

Determination G1 or G2

Relevant code and clause EN16907-2:2019, cl6

S1, S2, G3, G4, S3, S4

EN16907-2:2019, cl6

Particle size distribution Proctor density and optimal water content Water content: ±2% of optimal water content derived from Proctor test F’ = 40o, E = 100MPa at 100kPa reference stress Dr = 100%, Ev1 > 35Mpa, lo < 2.2

EN16907-2:2019, cl8, Table 13 and Annex 1 EN ISO17892 Parts 5, 9, 10 EN16907-5:2019, cl8 EN16907-1:2019, Annex B

Parameter Embankment construction speed Ground model – indirect evidence Source: Developed by the Authors

Determination

Relevant code and clause

Not faster than one layer per week or as stated during results analysis

Design based

CPT or boring equipment

-

parameters – qc, fs and lithology

Table 5. Information relevant for Monitoring and Maintenance

Parameter Settlement Horizontal deflection Pore pressure dissipation Signs of slope stability failure Source: Developed by the Authors

Determination

Relevant code and clause

< 100mm

Design based

< 20mm

Design based

90% of the measured increase

Design based

Regular inspections minimum of twice per

-

year (spring, autumn) + after heavy rainfalls

3.2.4 Supervision plan - comments The plan should define construction stages and refer to execution specifications. Examples of the main three stages are shown in figure 5. Depending on the need the plan will include more detailed information about each stage. It is important to be define how each construction stage will interact with other geotechnical structures or objects.

Figure 5. Elements of supervision

Source: Developed by the Authors In the described case, the installation of monitoring is a significant factor which affects the embankment construction speed. Clear design-based criteria are to be established as described in the monitoring plan.

3.2.5 Inspection plan – comments According to the inspection plan definition there are three areas which need to be covered: Figure 6. Elements of inspection Source: Developed by the Authors Material and products properties. — Material and products shall be used according to the execution specification, project content and relevant codes. In this case these are the materials used for the construction of the embankment. During execution, the embankment will be constructed in layers. Each layer needs to represent appropriate quality – see table 4. — The embankment material parameters used in the design need to be checked to verify the geotechnical design. In a typical case when the embankment is made of sandy material the key parameters may include: effective friction angle, relative density (used in stability analysis) and appropriate modulus of the soil (used in settlement calculations). In the annexes to EN 16907-2 an exhaustive list of related standards is given for in situ and laboratory testing of those parameters. Dimensions and quality — The plan should contain measures to confirm that the execution is implemented according to the work description and applicable method statement. In EN 16907-5 quality control procedures regarding in situ density testing, stiffness and bearing capacity testing (plate load test and others) are included. Frequency of testing, geometrical tolerances and general information about monitoring are also included there. — In this example, the very weak soil layer means that the speed of embankment construction may be limited by the soil behaviour. Typically, as a first step it is assumed that layers are constructed no faster than one per week. — The use of GPS based systems to control the geometry of the structure as it is constructed is an example of how to reduce the potential for human error. Any work done by equipment working with such systems should be checked by traditional methods. — Quality of the drainage system needs to be checked as well as a part of the embankment structure.

Ground conditions / ground model — The encountered ground conditions should be checked for compliance with the ground model and geotechnical design model in line with appropriate provisions included in the Inspection Plan. — Evidence / direct comparisons are preferred – that can be comparison of lithology, soil state, soil type, water table level. Simple visual methods can be used by the site personnel - for example to monitor the water level in a well. In this example some indirect methods are applicable – pressure gauges can be installed using CPT equipment and inclinometers should be installed after borehole execution. Indirect evidence includes parameters of penetration and lithological output from boring, this could be used to identify the base of the soft soils. The geotechnical designer should interpret the records, compare with the available soil investigation and confirm there is no deviation from the design assumptions. Due to the very weak soil layer there is a specific need for pore pressure monitoring (or frequently cu testing). Acceptance criteria needs to be established based on those values. — As there are no neighbouring structures and the buried pipeline is quite shallow (2m depth) in this case the zone of influence covers mainly subsoil. As the stronger sandy stratum is relatively shallow, the zone of influence was judged to be at the depth of 12m (7m of soft soils +5m). In other geological conditions (especially when there are only fine grained soils) the zone of influence could depend more on the embankment width – in this case 31m across the base which will lead to a larger depth of zone of influence. 3.2.6 Monitoring plan – comments Figure 7. Elements of monitoring Source: Developed by the Authors — In the case of a simple embankment no monitoring is usually needed; however, in this case two reasons to install monitoring can be found: the presence of the pipeline and the very weak subsoil. — For the buried pipeline the need for monitoring will depend on the pipeline condition, structure, and deformation limits. A condition assessment might be required in advance of embankment construction, if practical.

— When very weak subsoil is present, then monitoring is necessary. In this example several instruments are used: plate settlement gauges (benchmarks), horizontal inclinometer, vertical inclinometer and pore pressure sensor. The aim is to monitor settlements, horizontal soil movement and pore pressure. Additional information about specific techniques can be found in EN-ISO 18674-1, EN-ISO 18674-2, EN-ISO 18674-3, EN-ISO 18674-4 and EN-ISO 18674-5. (Detailed information can also be found in Dunnicliff (1988). — To choose the best monitoring technique for settlement the level of expected settlements needs to be estimated and the time when these settlements will occur. It makes no sense to use automatic systems for simple cases where embankment height is not significant as settlements occur only during construction (no creep settlements possible). A precision of 0.1mm is not needed, as a range of 10mm will be sufficient when several cm of movement is expected. Automatic systems are appropriate under buildings of high importance or when the effects of soil displacement can cause significant damage. The information about settlement is however only useful when combined with knowledge of the cause of those settlements. In order to provide sufficient information, it is therefore highly recommended to measure the embankment geometry and soil relative density to estimate the load. — In the case of vertical inclinometers it is very important to have a benchmark on the top to have a result in the form of absolute displacement. Without the benchmark the measurement will give only relative displacement which can lead to underestimation of displacement or wrong deformation form. This should be defined in the monitoring plan. — For long term monitoring ABS or similar especially designed casings are required, however for temporary monitoring steel profiles can be used. Steel cannot be used for long term because of its tendency to rust which can cause blocking of inclinometer wheels. — In the case of pore pressure sensors the method of installation and the range can play an important role. The designed method (technique) of monitoring should give results in a relevant resolution. Pressure sensors which are designed to be driven in or pushed into soft soil are preferable in the described case. — In this example monitoring should be undertaken: — before execution of the embankment, to establish reference conditions (zero-reading);  during execution, to identify the appropriate speed of embankment construction (reading after building each 1.6m – 4 layers)  after execution, to evaluate the long-term performance of the structure (caused by the traffic or creep of clay in this case, one year periods are suggested initially). — It is recommended that if the verification of a limit state is sensitive to a specific ground property, the Monitoring Plan should include provisions to verify the design assumptions made for these ground properties. In this case global stability is sensitive to the strength parameter of the weak soil and embankment material. Properties of both should be tested (checked) during the inspection and supervision – see table 4. 3.2.7 Maintenance plan – comments The maintenance of embankment structures is very limited in practice, or often does not exist. In most cases there are no reference documents for this topic and so it should be agreed between the

parties. In the described case where the monitoring is already installed it can be used during the maintenance period. The frequency of reading should be adapted to the observed results, with a one year period being a potential starting point. The second maintenance aspect could be slope stability and the verification of visible signs of instabilities. While carrying out regular maintenance of the slopes (grass cutting several times per year) the signs of stability failure should be identified. In this case appropriate measures should be taken to prevent failure if possible. 3.3 Case study 2 – Spread foundations 3.3.1 Introduction This subchapter provides suggested guidelines for inspection, supervision, monitoring, and maintenance plans for pad foundations. In the absence an execution standard for spread foundations, it has been assumed that the plans were developed based on agreement between the parties and taking into account the requirements of EN 1997-1, EN 1997-3 and EN 13670:2009 execution of concrete structures. The main items that would need to be verified are shown in figures 9, 10 and 11. They are related to both the foundation structure and to the geotechnical component as well. The figures are added to illustrate the content of table 6. What is important is that the information crucial for the design is to be verified – in this example that might be levels, material densities, soil model. The figures show the most important aspects, but a more extensive checklist could be developed following the examples for other structures shown in the Annex. 3.3.2 Data This example deals with the pad foundation for a column in a school construction project with the following characteristics: — Load on the column: 550kN (characteristic combination of the serviceability limit state) — Cross section of the column: 0.3m * 0.4m — Grid spacing of column: 5.0m * 5.0m — No other structures exist in the vicinity of the project Ground conditions are: — From ground surface to -8.10m: interbedded sandy / clayey silt and clayey / silty sand with average NSPT=13 and qc=3.5 MPa — From -8.10 to -13.60m: medium dense silty / clayey sand with average NSPT=18 and qc=4.5 MPa — From -13.60 to -20.00m: medium to dense silty sand with trace of gravel and average NSPT=30 and qc=19.0 MPa The ground water level was measured 3.00 m below ground surface. Geotechnical category is GC2. In order to control settlements, the allowable bearing pressure in the serviceability limit state is limited to 220 kPa.

Each column of the building will be founded on pad foundations installed 0.70 m from the ground surface (frost protection requirement is respected). Figure 8. Plan view of pad foundation

Plan dimensions and embedment in accordance with design?

Correct arrangement of steel reinforcement in relation to design?

Source: Developed by the Authors Figure 9. Cross section A-A. Sectional view of pad foundation Pending column reinforcement

cover respected?

Concrete formulation in accordance with exposure class and design requirements?

Material certificate for steel in accordance with design? Source: Developed by the Authors

Figure 8. Cross section B-B. Sectional view of pad foundation

Stable excavation walls? Need to be protected by formwork? No water at the bottom of the excavation? Ground layer and anchoring in accordance with sizing studies? Frost protection respected?

Quality of the backfill, and its compaction, in accordance with sizing studies (unless concreting the full excavation)

Source: Developed by the Authors

3.3.3 Summary of the plans for supervision, inspection, monitoring and maintenance The outcome of this example is table 6, which contains the main information necessary to perform supervision and inspection for the project. The table has the essential outcomes of the design, which should be included in documents supplied for the execution stage, in a prominent position such as in the drawings.

Table 6. Content of plans for supervision and inspection

Parameter Geotechnical category Plan dimensions Implementation tolerances Arrangement of steel reinforcement Concrete cover Material certificate for steel Concrete grade Ground layer at the bottom of the excavation

Determination GC2 1.4m * 1.8m 25mm (in each direction) 11HA10 (e=160mm) & 10HA12 (e=140mm)

Relevant code EN997-1, cl 4.1 EN1997-3, cl 5.5 EN13670, Annex G.10.3. EN1992

30mm B500B C25/30, XC2 Interbedded layers of sandy, clayey silt and clayey, silty sand

EN1992 EN1992 EN1992 / EN206-1 EN1997-3, cl5.5

Parameter Water level Stability of excavation sides Quality of the backfill around spread foundation Compaction of the backfill around spread foundation Source: Developed by the Authors

Determination No water at the bottom of the excavation Stable or protected by formwork Full excavation will be concreted, no backfill

Relevant code EN13670, cl8.2(5) EN13670 cl8.2(6) EN1997-3, cl5.5

3.3.4 Supervision plan - comments For this project, the supervision plan may address the following: — To check if the side of the excavation are stable or protected by formwork:  Excavation sides should be stable in the example — To check if the quality of the backfill, and its compaction, around the spread foundations are in accordance with the design (unless full excavation concreted):  Full excavation will be concreted in the example

3.3.5 Inspection plan - comments For this project, the inspection plan may address the following: — To check if at the base of the excavation, the bearing material is in accordance with the design assumptions:  Interbedded layers of sandy / clayey silt and clayey / silty sand  no water — To check if the plan dimensions and installation tolerances of the spread foundations are in accordance with the design input:  1.4m * 1.8m with a plan tolerance of 50mm (in each direction) in the example — To check if the arrangement of steel reinforcement matches with the design input:  11 HA10 (e = 160mm) and 10 HA12 (e = 140mm) in the example — To check if cover depths are respected:  30mm in the example — To check if the material certificate for the steel is in accordance with the design requirements:  B500B in the example — To check the concrete design is in accordance with the exposure class and design requirements:  C25/30, XC2 in the example

3.3.6 Monitoring plan – comments For this project, the monitoring plan is not required. Note: Monitoring plan would be required for more complex GC3 projects such as bridges foundations, large vibrating machines foundations, etc. 3.3.7 Maintenance plan – comments For this project, the maintenance plan is not required. Note: Maintenance plan would be required for more complex GC3 projects such as bridges foundations, large vibrating machines foundations, etc. 3.4 Case study 3 – Bored piles 3.4.1 Introduction In the presented example, (see figure 12), a plan for supervision, inspection, monitoring and maintenance is developed. The plan provides the basic determinations, which are necessary for quality control to a level required by EN 1997:2024. The result is summarised in table 7, which contains the main information necessary to implement design into execution for the project. Further guidance is given where additional information in standards related to the subject is found. Where a European standard was not found the relevant national code is quoted. The table as essential outcome of the design, which leads to multiple actions shall be positioned prominently in documents used for tender and execution e.g. in drawings. An intensive study of the relevant execution standards dealing with bored piles and reinforced concrete and steelworks needs to be carried out alongside the requirements of the plans produced by the design team. Figure 9. Example bored pile foundation under a highway bridge Source: German Geotechnical Society, EA-Pfahle

Table 7. Plan for supervision, inspection, monitoring and maintenance

Basic Determinations

Basic Requirement

Determination

Relevant code and clause

Consequence class Design service life Minimum design quality level Minimum design check level Geotechnical Category Minimum Inspection level Durability design criteria ULS (Settlement with failure of structure or ground) SLS (settlement that causes damage to elements other than structural) Environmental criteria

CC3a–Higher (lower risk group) Tlife = 100 years DQL3 DCL3 GC3 IL3 SULS = 130mm SSLS = 40mm

EN1990:2021, table 4.1 EN1990:2021, table 4.5 EN1990, table B.1 EN1990, table B.2 EN1997-1, table 4.2 (NDP) EN1990, table B.3 EN1990, cl 4.6 EN1990, cl5.3 EN1990, cl5.4

Soil & groundwater is not aggressive

National documents (1)

Information relevant to Supervision and Inspection

Production method

Determination

Relevant Code and clause

Pile Type Drilling method Support fluid Geometrical tolerances

Bored Piles Kelly piles with casing none Determination

EN1536 cl 9 & 10 EN1536 Annex C.1 & Annex C.2 EN1536 Annex C.3 & Annex C.4 Relevant Code and clause

Position in plan Verticality Material

e < 0.1*D; 1.0m < D< 1.5m i < imax = 0.02m/m, f > 86⁰ Determination

EN1536 cl 8.1 Relevant Code and clause

Concrete Reinforcing steel Construction steel

C25/30 500 B S235

Monitoring and Maintenance Plan

EN206, EN13670 EN1992 EN1090-2

Pile testing

Determination

Relevant Code and clause

Static load test Integrity test Measured variable

Test proof load = 2.6MN Method: low strain integrity test Necessary activity/element

EN1536 cl 6.9 EN1536 cl 9.2.3.3

During construction After construction

Relevant Code

Settlement of pile head during lifetime

Installation of benchmark on bridge pier Reference measurement after construction

Regular measurement

Period 3 years

Documentation Structure log

Refer to national documents

(1) National documents may apply

Source: Developed by the Authors

3.4.2 Basic determinations – quality management measures

3.4.2.1 Determinations and relevant clauses in the code According to EN 1990-1:2023 clause 4.8 (1) appropriate quality measures should be implemented to provide a structure that corresponds to the design requirements and assumptions. Namely

organizational procedures in design, execution, use and maintenance and further controls at the stages of design, detailing, execution, use and maintenance should be implemented. This example, a highway-bridge with pile foundations, is in consequence class and geotechnical category three. This structure then to be classified with the accordant design quality, design check and inspection level. The relevant sections of the code are given in table 3. The maximum allowable settlements in the SLS and ULS are defined depending on the relevant design criteria. 3.4.2.2 Comment The measures to ensure the required concrete quality are part of EN 206 and EN 13670. EN ISO 17660 regulates welding of reinforcement and EN 1090-2 welding of construction steel and the accordant quality measures. These regulations are not considered within the present example.

3.4.3 Supervision and inspection plan – comments Depending on the type of pile and the execution method the execution standard defines the measures necessary for quality control during execution. In the case considered, rotary bored Kelly piles with casing are executed, which are treated in EN 1536. Table 8 gives a shortened overview specified in this document for the quality measures required during execution.

Table 8. Quality measures for bored piles during execution, based on EN1536, Table 8.

Number 1

Subject Identification and as built position 1.1 bored pile reference number 1.2 depth of bored pile Etc.

Cased/uncased excavation X X X

Excavation supported by fluids X X X

Continuous flight auger piles X X X

Excavation information

X

X

X

2.1 excavation time

X

X

X

Etc.

Ground conditions

3.1 Drilling log

X

X

(X)

3.2 Ground water table

X

X

(X)

Etc.

Support fluid

Concreting information

Reinforcement

Precast concrete elements

External grouting

Prepacked piles

Shaft and base grouting

Sub items for numbers 4 to 10 not listed here

X: necessary information

(X): information as applicable

---------: not applicable

Source: EN 1536

3.4.4 Monitoring and maintenance plans – comments In this example, static load tests shall be performed in accordance with EN1997-3, clause 6.9.4. The execution of the tests shall comply with EN ISO 22477-1. The test proof load is determined to be 2.6MN. The procedure to develop design pile loads from the pile test is not covered within this example. To demonstrate that the required quality has been achieved, integrity testing of the piles in accordance with EN 1536, clause 9.2.3.3 should be performed. In addition, the settlement of the pile head is monitored during the service life and measuring bolts are installed in the pile cap. A reference measurement is carried out after construction of the pile foundation and a subsequent measurement after completion of the structure. These actions provide an indication of whether the foundationsettlements are within the limits. The measurements are repeated regularly during the lifetime of the structure. The intervals and measures for documentation are dealt with in relevant national codes.

3.5 Case study 4 – Anchors

3.5.1 Introduction Anchors are specific geotechnical elements where the execution and testing are integrally linked to the design. There are two main documents which the design and the plans should refer to: — ISO 22477-5:2018 Geotechnical investigation and testing — Testing of geotechnical structures. Part 5: Testing of grouted anchors — EN 1537:2013 Execution of special geotechnical works - Ground anchors

3.5.2 Data A cross section of a retaining wall in reinforced concrete to support a 120 m long cut for a new main road is shown on figure 13 and described in the following text.

Figure 10. Geometry and data of the example

+/- 0.0 m

- 2.5 m - 5.0 m

Sandy gravel

10°

- 3.5 to - 5.0 m

Clayey sand

Source: Developed by the Authors — Ground water table: > - 10 m — Design force per anchor: 400 kN, number of anchors: 60 — Anchor type: grouted anchor, permanent

— Fixed length: 5 m, free length: 7 to 15 m, Inclination: 10° — Characteristic internal anchor resistance: 558 kN, proof load (investigation tests): min. 558 kN, proof load (suitability and acceptance tests): 419 kN, lock-off load: 335 kN — Zone of influence: approx. 20 m wide and approx. 10 m deep — Geotechnical complexity class: GCC2 (normal), Consequence class: CC2 (normal) -> Geotechnical category: GC2. Design service life / durability: 50 years

3.5.3 Plans A simple example of the content for the plans required is presented in Table 9.

Table 9. Example content for the four plans.

Check of anchor products delivery & handling

Supervision plan Specification checks, transport, handling and installation of tendons

Supervision of the process of borehole drilling

Tolerance of borehole diameter & collar axis at the anchor head. Tolerance of the angle of inclination and borehole axis

EN1537

Grout specification and components

Compatibility with ground conditions

Borehole testing (to ensure that the fixed length is fully grouted after the grout has set)

Through using water testing, falling grout test or by pressure grouting

EN1537

Supervision of the process of anchor installation

Water/Cement ratio, mixing efficiency and mixing time, grout volume injected/loss of grout volume, injection pressure

Inspection Plan (all tests must be executed to EN ISO 22477-5 Limiting criteria for investigation, suitability and acceptance tests (EN1997-3, table 8.3)

Anchor investigation tests (to establish the ultimate load resistance of the anchors at the grout/ground interface)

3 test anchors Test method 1 (the anchor is loaded in steps for one or more load cycles increasing from the datum load to the proof load. At each load step the displacement of the tendon end has to be measured over a fixed time period) Proof load: minimum of 558kN

Limiting criteria: creep rate per log cycle of time: aULS = 2mm

Anchor suitability tests (to document the ability of the anchor to resist the proof load and assess the behaviour of the anchor system up to proof load in terms of creep rate or load loss)

6 anchors (10% of total number) Test method 1 (see above) Proof load: 419kN

Limiting criteria: creep rate per log cycle of time: aULS = 2mm

Anchor acceptance tests (to document the ability of the anchor to resist the proof load, the apparent free length and the lock off load)

54 anchors Test method 3 (the anchor is loaded in incremental steps from a datum load to a maximum load. The displacement of the

Limiting criteria: creep rate per log cycle of time: aULS = 1.5mm

Grout material tests Electrical testing of corrosion protection Measurement of forces Measurement of forces Electrical testing of corrosion protection Restressing of anchors Replacement of anchors Source: Developed by the Authors

Supervision plan tendon end is measured under maintained load at each loading step) Proof load: 419kN Test of compressive strength, prior to use 2 series of tests for every 20m3 of mixed grout 3 samples Every anchor to be tested Anchors to be tested after stressing Test methods: ERM I and ERM II according to EN1537:1999 If feasible test method ERM I should be adopted Monitoring Plan 3 anchors (5% of all anchors) equipped with monitoring facility Time of measurements: end of construction Maintenance Plan 3 anchors (5% of all anchors) 2 additional anchors for validation purposes (tensioning with stressing equipment) Interval: every 10 years 6 anchors (10% of total number) Test method according to EN1537 Interval: every 10 years Restressing of individual anchors in the case of declining anchor forces In the case of abnormal changes in forces of deformations

EN1997-3, cl 8.9.1 Acceptable level: ERM I: > 0.1MΩ ERM II: > 100Ω

3.6 Case study 5 – Reinforced fill structures

3.6.1 Introduction A base reinforced piled embankment consists of a reinforced embankment on a pile foundation, see figure 14. Via arching, the force of the super structure is transferred preferentially to the stiffer elements in the ground (in this case, piles).

Figure 11. Base reinforcement under embankment example Source: Developed by the Authors Possible references useful for establishing the plans are mentioned below. Please note that these are partially related to the design and partially to execution and contain useful information about the link between those two. 1. CUR226, 2016. Design Guideline Piles Embankments, updated version in Dutch. 2. EN1997-1 : Geotechnical Design- Part 1: General rules including the National Annex. 3. EN1991-2: Actions on structures-Part 2: Traffic loads on bridges, including the National Annex. 4. EN 13242+A1 Aggregates for unbound and hydraulically bound materials for use in civil engineering work and road construction. 5. EN 14199, 2015. Execution of special geotechnical works – Micropiles 6. EN 14475, 2006. Execution of special geotechnical works- Reinforced fills 7. EN 12699, 2015. Execution of special geotechnical works - Displacement piles 8. EN 13251, 2014. Geotextiles and geotextile-related products-characteristics required for the use in earthworks, foundation and retaining structures Note: Rules described in the design guidelines for base reinforced piled embankments are dependent on which national standard is used. These standards include design rules on validating conditions, which must be met. However independent of the design method, the implementation and plan content should remain similar – for example it does not matter how the geosynthetic strength was calculated, what is important is how to check / prove it during the execution (inspection in this case). More important aspects are highlighted but a more extensive checklist of relevant aspects is presented in point 3.9.3. 3.6.2 Data All the essential data are shown below on Figure 15.

Figure 12. Base reinforcement under embankment example Source: Developed by the Authors 3.6.3 Supervision plan – comments — Where reinforcement is to be placed over piles, there should be a chamfer to the edge of the pile caps and/or the pile caps covered with a layer of fill to prevent damage to the reinforcement, (EN 14475 par. 8.3.1.5). — If required in the design, material to protect the GR from damage by the pile caps should be applied. The foundation shall be constructed to the levels and falls in accordance with the requirements of the design. — For the aspects of placement of the reinforcement, see EN 14475 par. 8.5.3. Some key points are highlighted below:  Reinforcement should be laid on an even surface.  Ensure that the non-rigid reinforcement is tight and that any slack has been removed.  Reinforcement should extend in one continuous piece in the main load carrying direction.  Polymeric reinforcement may be prone to degradation when exposed to sunlight and therefore should be covered with fill within a specified time of laying. Where no such time is specified, exposed reinforcement should be covered within 24 hours of placement. — For the aspects of placement of the compaction fill, see EN 14475 par. 8.5.4. — Check if groundwater is according to design. A higher groundwater level in combination with clay or peat at the sides creates risks of instability.

— Check end bearing capacity from blow count analysis for cast-in-situ piles, by means of applied loading force. In case of insufficient load-bearing capacity, it may be necessary to install an extra pile, subject to design review. — After placing the pile caps, the soil between these pile caps should not be compacted in order to allow some strain of the grid during the execution phase, so the end deformation is reduced. — During the execution phase, the embankment will not be at its full height. However, working traffic is already acting on the structure. A lower embankment means less arching, thus higher loading of the grid. So, in the execution phase the in-service height of the embankment should comply with the limits set in the design. — Regarding the granular fill, the following activities during execution should be carried out:  Check if the applied reinforcement is in its place. To ensure the position it is recommended to apply a small amount of the fill material.  Check that fill material is tipped directly on the GR out of the truck. The truck should tip its load on the already constructed works, after which the material should be spread out evenly over the GR.  Check that compaction of layer is according to the compaction requirements (usually at least 98% standard Proctor density).  Check that construction equipment is not directly driven on the GR. Add at least a base layer of 0.4 m fill.  If the design requires, the reinforcement along the edges should be wrapped back. — If the edges being wrapped back for some reason is not possible, it should be demonstrated that the force at the toe of the slope from the reinforcement layer to the piles and from the fill to the piles is sufficient. — If in the design for the grid, a sub grade ks is taken into account at the end of the service life, this should be guaranteed. The soil properties of the sub soil between the pile should be such that settlement requirements are met. — Make sure that during execution, the soil between the piles is not overloaded, e.g. by choosing a thicker working platform to avoid settlements (and absence of subgrade). — Regarding the overlaps, the following activities during execution should be carried out:  Avoid unnecessary overlaps in the longitudinal direction.  Overlaps in the transverse direction (perpendicular to the strong direction) should lie above the pile caps and not in the span between them.  Pile caps should be visible during laying grids, in order to control the correct position of the overlaps. If pile caps are covered, their locations should be marked.  Verify if the required overlap in the transverse direction is used in the execution phase.  If overlaps are replaced by stitched seams, reduction of reinforcement strength and the change in its strain behaviour should be included in the calculation. — GR should be installed without folds, creases or undulations, but not pretensioned.

— Without any calculations, the overhang of the pile cap should be at most 0.5deq. 3.6.4 Supervision plan – comments — Observation during construction shall conform with EN 1997-1 (clause 2.7). In EN14475 par. 7.4 and 7.5 some possible aspects of design output are specified. — Geosynthetic material shall be identified with clear marks or labels and conform to EN ISO 10320. — For quality control and handling and storage, see EN14475, par. 8.1 and 8.2. — In the design reduction factors are used based on information provided by the suppliers of the grid (Isochronous curves given by grid manufacturer). Since time can pass between design and execution, these factors should be double-checked with the provider of the grid at time of delivery. — While using prefabricated pile caps, the connection of both elements should be such that the pile head is supporting the pile cap over the entire contact area. This to avoid peak stress in the pile cap. — The quality of each pile must be checked after installation if the integrity cannot be guaranteed. — To ensure that the geosynthetic reinforcement is not damaged at the pile edges, the edges should be rounded off and or provide a protection between reinforcement and pile caps. — Quality of fill material should be chosen taking into account the imposed environment and structural requirements. Requirements for the reinforced embankment:  Inspection of fill. It should not contain any sharp objects that could damage the geosynthetic reinforcement.  Check if internal friction angle of design is met.  If recycled aggregate is used, check required particle size grading. Recommendation: 0 / 31.5 or 4 / 31.5 mm to 0 / 63 or 4/63 mm according to EN13242. — Avoid using crushed demolition waste aggregate with low hydraulic conductivity. — The pile setting out and spacing should be according to design. 3.6.5 Monitoring and maintenance plan – comments Due to the low settlements expected after construction, this type of construction requires less maintenance. At most the transition from a piled embankment to a conventional embankment may need some maintenance to compensate for any differential settlements. Check if monitoring is needed at transition zone according to the design. If monitoring is needed, measuring hoses can be placed on the grids during execution, to monitor settlement during the execution phase and or during the structure’s life cycle. Future embankment widening or installation of cables and pipelines is difficult. It is crucial to formulate a maintenance strategy for the entire life cycle of the structure.

Figure 13. Example of monitoring arrangement Source: Developed by the Authors Some attention points for maintenance: — For example, incorporation of utilities in advance e.g. empty ducts, or cable tunnels. — Lowering the surface level adjacent to the pile embankment could lead to horizontal soil deformation that might exert an unsafe loading on the piled embankment. — During maintenance of the verges and slopes, account should be taken of the presence of the GR. — A possibility for inspection of material is to enclose non-functional pieces of the GR that are subjected to the same conditions as the “functional” GR. This sample can be tested to obtain information on the rest of the reinforcement present in the embankment. — Asset manager should check for damage by rodents, termites, etc. 3.7 Case study 6 – Rigid inclusions 3.7.1 Introduction This part suggests guidelines for inspection, supervision, monitoring, and maintenance plans of a ground improvement project with rigid inclusions (RI). In the absence an execution standard for RI, it is assumed that the plans were developed based on agreement between the parties and taking into consideration the stipulations of both EN 1997-1 and EN 1997-3. 3.7.2 Data This example relates to a waterfront project with three (3) new tanks for liquid storage shown on figure 17 and 18 with the following characteristics: Tank 1 (concrete tank) – Foundation diameter 32.94m, average contact pressure 81 KN/m2 Tank 2 (steel tank) - Foundation diameter 21.82m, average contact pressure 171 KN/m2 Tank 3 (concrete tank) - Foundation diameter 9.10m, average contact pressure 88 KN/m2.

Figure 14. Tanks and rigid inclusion layout Source: Developed by the Authors Figure 15. Tanks and rigid inclusion cross section Source: Developed by the Authors Soil and groundwater conditions are: — From ground surface to -2.70 m: soft silty clay with average NSPT=5 and qc=0.50MPa — From -2.70 to -8.10 m: intercalations of sandy / clayey silt and clayey / silty sand with average NSPT=13, qc=3.50MPa, and fs=0.05MPa — From -8.10 to -11.20 m: soft clayey silt with average NSPT=7, qc=1.0MPa and fs=0.15MPa — From -11.20 to -13.60 m: medium dense silty / clayey sand with average NSPT=18, qc=4.5 and fs=0.2MPa

— From -13.60 to -27.00 m: medium to dense silty sand with trace of gravel and average NSPT=30, qc=19.0MPa and fs=0.2MPa — Below this depth the soil is considered as not compressible. The ground water level was measured 1.50 m below ground surface. No other structures exist in the vicinity of the proposed silos. The ground improvement solution comprises a total of 320 concrete rigid inclusions having a diameter of 400 mm and net length of 13.20 m (starting -1.80 meters below ground surface to -15.00 meters). They are designed as full displacement. In addition, the inclusions are un-reinforced and they are topped by a Load Transfer Platform (LTP) that transfers the structural loads to the RI. The distribution of inclusions is 158 for tank 1,147 for tank 2, and 15 for tank 3. Geotechnical category is GC2.The design service lifetime is 50 years to match the tank structure. 3.7.3 Supervision plan – comments Supervision should be performed in accordance with the stipulations of EN 1997-1 section 10.2. For this project, the Supervision Plan may address the following: — To execute the works with a special displacement tool and suitable machines, which can apply the necessary torque and pull-down force to the full design depth. To apply the full displacement method in which soil is not extracted but instead it is displaced laterally. — To ensure that the time between rigid inclusions execution and silos initial filling is appropriate; therefore, the excessive pore pressure can dissipate. — To execute the inclusions in a specific pattern determined by the execution specifications and which may be adjusted during execution based on observations. — To assure safety procedures especially in terms of working platforms quality. — To provide measures during execution in order to ensure the geometrical properties. 3.7.4 Inspection plan – comments — Inspection has to be performed in accordance with the stipulations of both EN 1997-1 section 10.3 as well as EN 1997-3 section 11.8.2 Inspection and section 11.9 Testing. — As mentioned earlier in this example, the inclusions are constructed starting from -1.80 meters below ground surface down to -15.00 meters. Thus, the inclusion tip is designed to be inside the final foundation layer (medium to dense silty sand with trace of gravel and average NSPT=30 and qc=19.0 MPa). — Based on the above, the Inspection Plan may address the following for validating the design assumptions in terms of ground conditions and performing Control Testing:  To ensure that a competent bearing layer has been reached it is required to perform calibration drilling (preferably with the aid of bespoke recording equipment) at the beginning of the work in order to define a refusal criterion. The criterion is applied to all inclusions during construction and in case of discrepancies the Designer shall be notified.  The volume of concrete necessary for constructing the inclusions shall be recorded with depth (preferably with the aid of bespoke recording equipment) and in case of excessive under or over consumption the Designer shall be notified.

 In terms of bearing capacity, a load test on an individual inclusion shall be performed following the appropriate specifications.  UCS testing according to table 11.5 of EN1997-3. 3.7.5 Monitoring plan – comments — Monitoring to be performed in compliance with the stipulations of EN 1997-1 section 10.4. — The Monitoring Plan should address the following:  During construction: Not required.  After construction, for the initial filling: Initial filling of the silos shall be performed with a specific loading and monitoring schedule. During this operation, measurements shall be taken at all silos in terms of both absolute and differential settlements. The monitoring results are to be used to verify the design assumptions prior to the start of normal usage of silos.  After initial filling, for the service life of the structures: Periodic measurements shall be taken at all silos in terms of both absolute and differential settlements. 3.7.6 Maintenance plan – comments — Maintenance to be performed in accordance with the stipulations of both EN 1997-1 section 10.5 and EN 1997-3 section 11.8.4. — The Maintenance Plan should address the following during the course of the service life of the structures:  Protect the LTP from erosion and hydraulic phenomena by wrapping it inside geofabrics and if necessary, perform repairs.  Rigid inclusions are buried; therefore, no measures are needed. 3.8 Case study 7 – Groundwater control 3.8.1 Introduction A generic case of groundwater control is presented as an example for establishing supervision, inspection, monitoring and maintenance plans. More important aspects are highlighted but a more extensive checklist of relevant aspects is presented in the example checklist in the Annex. 3.8.2 Data – dewatering of an open excavation — The example shown on Figure 19 represents groundwater control through dewatering by pumping.

Figure 16. Illustration of the example of ground water control through dewatering Source: Developed by the Authors — The soil is frictional material representing an unconfined groundwater aquifer — Groundwater lowering/dewatering will be performed:  Temporary during construction phase to mitigate the risk of hydraulic uplift and excessive groundwater ingress while performing open excavation for foundation works.  Permanently through drainage of the geotechnical structure. — The example represents geotechnical category GC3 since there are buildings at risk of groundwater lowering located within the zone of influence. As a consequence, there are limit values for groundwater levels for certain structures within the zone of influence. 3.8.2.1 Key design parameters — Soil/rock stratification — Hydraulic units/aquifers — Hydraulic parameters of soil — Well capacity of pumping wells — Extraction volumes — Robustness of dewatering operation:  Stability of excavation (extraction capacity)  Mitigation plan in case limit values for groundwater levels are exceeded — Groundwater levels (Pre-work/Construction phase/Permanent phase):  within excavation  within the zone of influence  at sensitive objects  of hydraulic units

— Drainage volumes — Maintenance measures — Layout and design of the groundwater control system.

3.8.3 Checking for relevant execution standards Table 10 can be used to check which standards or documents needs to be checked while making the link between the design and execution and writing plans. Plans might include this kind of list at the beginning to show to the execution team what the basis of the plans was and what documents they need to refer to in order to understand the design fully.

Table 10. List of standards potentially relevant to groundwater control (based on example in section 3.8.2)

EN 22282-1:2022

Geotechnical investigation and testing Geohydraulic testing Part 1: General Rules

EN 22282-2:2012

Geohydraulic testing Part 2: Water permeability tests in a borehole using open systems

EN 22282-3:2012

Geohydraulic testing Part 3: Water pressure tests in rock

EN 22282-4:2021

Geohydraulic testing Part 4: Pumping tests

EN 22282-5:2012

Geohydraulic testing Part 5: Infiltrometer tests

EN 22282-6:2012

Geohydraulic testing Part 6: Water permeability tests in a borehole using closed systems

EN 22475-1:2021

Sampling methods and groundwater measurements; Part 1: Technical principles for execution

EN 14688-1

Identification and classification of soil; Part 1: Identification and description

EN 14689-1

Identification and classification of rock; Part 1: Identification and description

EN 12063

Sheet pile walls

EN 12715: 2020

Grouting

EN 12716:2018

Jet Grouting

EN 14679:2005/AC:2006 Deep mixing

EN 1536:2010+A1:2015 Bored piles

EN 12699:2015

Displacement piles

EN 1537:2013

Ground anchors

EN 15237

Execution of vertical drainage

EN 1538:2010+A1:2015 Execution of diaphragm walls

EN 16228-1:2014

Drilling and foundation equipment - Safety - Part 1 common requirements

Relevant Y Y N Y N N N Y N N N N N N N N N N Y

EN 16228-2:2014

Geotechnical investigation and testing Drilling and foundation equipment - Safety - Part 2 - Mobile drill rigs for civil and geotechnical engineering quarry and mining

Source: Developed by the Authors

Relevant Y

3.8.4 Supervision plan – comments The supervision plan may address the following: — Hydraulic tests and well installation according to execution standards and specification in the design. — Installation procedures and design of system for groundwater control are appropriate for the preconditions stated in the design (ground model) and verified by observations and data from foundation works. — Safety aspects for personnel. (Traffic arrangements, necessary qualifications for welding (hot) works, drilling rigs, safety protocol for high pressure hoses etc.) A valid measure could be to require work preparations for all works implying risk for personnel or third party. — Check installation according to design such as installation levels of well screens, filter sand, bentonite sealing, well casing in respect to execution specification. — Procedure for executing, assessment and documentation of well development process — Procedure and documentation for testing hydraulic function of well (falling head test) — Ensure data and observations relevant to design assumptions are communicated to design team to enable corrective measures if needed.

3.8.5 Inspection plan – comments Some parameters of the inspection plan are also considered in the monitoring plan to check compliance with design assumptions for serviceability criteria. — The characteristics of the groundwater system relevant to the geotechnical design and effects within the zone of influence shall be considered both before and after execution to ensure that the design is applicable. Relevant parameters: hydraulic conductivity, transmissivity, storage coefficient, groundwater levels/pressure, aquifers, aquitards, hydraulic contact, vertical and horizontal hydraulic gradients. In this case relevant information would be hydraulic properties of soils and soil profile, location and extent of more permeable or impermeable layers, well tests could yield information on hydraulic connectivity and the zone of influence. — Overall functionality of the dewatering system to achieve sufficient groundwater lowering within and throughout the whole excavation. Test of dewatering capacity from pump and well tests combined with measurements of groundwater levels. — Assess robustness of groundwater control system and establish contingency measures to mitigate disturbances (power / pumping failures). — Plan for mitigation measures if the limit values within the zone of influence cannot be maintained, potentially preparations to install infiltration wells.

— Diversion of rainwater and surface water from entering the excavation. 3.8.6 Monitoring plan – comments — The monitoring plan should include duration, type and frequency of monitoring, and locations of monitoring points. — Monitor groundwater levels within the excavation to check design requirements of groundwater levels can be maintained over time to prevent hydraulic uplift. — Frequency and extent of measurements for the different project phases:  Groundwater levels  Pumping volumes  Ground or structure settlements — Dewatering volumes (total drainage volumes from excavation) — Volumes of added process water — The capacity of the groundwater control needs to be assessed for the design lifetime of the groundwater control system. Declining capacities over time due to encrusting of well screens, silting of wells or sumps; wear in pumps, clogging of pumps needs to be handled through installation of additional wells or well rejuvenation. — Groundwater levels within the zone of influence are kept within requirements (limit or threshold values) 3.8.7 Maintenance plan – comments The maintenance plan is to address all components necessary for any permanent groundwater control. It would comprise any installations for drainage, infiltration or bypass of groundwater flow. The need for maintenance will be assessed by long term monitoring of parameters reflecting the functionality of the groundwater control system. It could comprise well cleaning, renewed filter development, chemical treatment of wells to prevent clogging of filters. 3.9 Checklists The use of checklists can be a convenient method to ensure that all items in a plan have been identified and verified as the design requires. The risk is that these become prescriptive and transferred from one project to the next without a review to revise it as required for the specific project requirements. This could result in an inadequate or overly onerous document being incorporated into the project. To aid the user of the Eurocode, some template checklists have been included in the Annex. These do not cover all the examples of geotechnical structures covered in this section but could be used as the starting point for those not covered. There are some types of geotechnical structure, such as grouted anchors, where the execution standard already contains a significant amount of the detail required and so a separate checklist may not be required.

4 Acceptance criteria 4.1 General concept Setting up acceptance criteria as points of reference for the execution stage is an important part of geotechnical design, linking the design and execution stages. There are mainly three types of acceptance criteria that should be specified prior to the execution, which can be related to: — Allowable execution tolerances – specifying the allowed deviation of the constructed geometry of the structure such that it is still considered of sufficient quality for use; — Performance indicators – used for comparison of observed behaviour with design predictions, for the purpose of validation of design, i.e. ensuring that the effects of execution are in line with design predictions; — Serviceability limit state criteria – established limiting values of observable quantities characterizing the behaviour of a structure in relation to its serviceability criteria. Although all these types of criteria should be specified in the design, for execution tolerances, usually reference to a relevant standard offers sufficient guidance for successful implementation of design in execution. However, depending on the structure to be designed, ground conditions and adjacent structures, execution tolerances could be stricter or larger than in the relevant standard. In contrast, performance indicators and serviceability limit criteria are mostly defined by a designer on a case-by-case basis, with only limited guidance provided in standards, literature, or by comparable experience. As a result, it is almost impossible to specify a universal set of acceptance criteria, which would not require the designer to apply at least some level of engineering judgement. The acceptance criteria should include not only specified values or ranges of values for the designed structure, but also for all relevant structures within its zone of influence. Acceptable limits related to third party assets are based on the designers’ assessment to determine the maximum acceptable impact on an asset in service which is critical for safety, serviceability or maintenance. It is worth distinguishing the limitations set on performance indicators, which may be related to the underlying uncertainty of design predictions, from those associated with serviceability limitations, which are directly related to limit state design verifications. However, both types are related to limiting values that should be set in design. In the case of serviceability criteria, further distinction can be made into levels related to: architectural damage (appearance), functional damage (use of structure), and structural damage (safety of structure). In EN1990 Annex A.1.8 there is informative guidance for serviceability criteria for buildings: vertical and horizontal deformations, vibrations and limiting foundation movements, which may be used when no other criteria are established by the designer, as the guidance is mostly related to aesthetic and serviceability requirements. On the other hand, railway and road authorities often have national criteria for settlements and change in gradient for their structures, which are mostly related to maintaining the functionality of the infrastructure. Therefore, criteria for embankments typically are based on vehicle speed and the required quality of the transport infrastructure.

For the implementation of design in execution, the acceptance criteria related to the performance of the structure are often associated with a set of trigger (threshold) values, used as a reference for monitoring. Those trigger values can be related to surface movements, stresses and strain within the support systems, and other parameters critical to the design. 4.2 Setting limits Limiting values are usually defined in terms of displacements, deformations, strains, groundwater or pore water pressure, vibrations or internal forces that can be measured and assessed during the construction. It is important that any behaviour deviating from the design assumptions, or which may lead to exceeding of a limiting state should be identified as early as possible. In practice, a color-coding (Traffic signal) system is often implemented to describe the levels of performance (e.g. green / amber / red), which are separated by prescribed monitoring trigger (threshold) values. The aim is to “trigger” a specified action, planned in advance in the case of a given reference value being exceeded. Figure 19. Illustration of the “traffic light” model for limits Source: Developed by the Authors There is no single approach to setting up the threshold values and this process will require engineering judgment. Often, trigger levels are set in reference to predicted values of performance indicators to ensure that the behaviour remains within the design assumptions. However, it is the value of the parameter together with the rate of its change that is important. Breach of trigger levels may indicate incorrect assumptions and result in the revision of values and trigger levels, even a revision of the design. Green and Amber triggers provide an early warning of a potential problem. The amber level may be set based on the prediction of behaviour using best estimate values of parameters. The amber level in such a case would mean that the predicted level has been reached. Provided that the rate of change of the parameters has stopped, then this would be considered as acceptable. As an example, the Green level may be considered as 75% of the Amber value and the Red value as 150 % of the Amber value (or related to the calculated ULS capacity of the structure being monitored).

Alternatively, trigger values can be related to the serviceability limits, as a percentage lower than 100%, which would represent the assumed limit. This approach can be particularly useful when the predicted deformations are relatively close in value to the limiting values. Steps to define these limiting values should include: — Step 1: Identifying key performance indicators or observable physical quantities that can be used to assess the performance of a structure in the context of design assumptions and expected serviceability limitations. — Step 2: Assessing limiting values at which the structure is considered to behave too far outside of the design predictions or when the relevant limit states can be exceeded (red level) – when immediate contingency measures need to be undertaken. — Step 3: Assessing limiting values at which sufficient early warning should be provided that there is a risk of falling outside of the design predictions or of exceeding the prescribed limit state (amber level). Usually, several different monitoring methods (measured indicators/quantities) and locations (structure, ground/groundwater close to construction activity) are needed at same construction site to observe the behaviour of structures and the ground. Some of them are highly correlative (i.e. strains and displacement of anchor head - anchor forces), some moderately correlative (i.e. vertical displacement - horizontal displacements or lowering of GW table - settlements) and some have no or only very slight correlation (i.e. vibration and GW table). When setting the limits, these correlations and the possibility of cross-checking different monitoring results should be taken into account. These correlations can be utilized during execution when analysing the reliability of the measurement results. An example of selecting a limiting value for the amber level may include considering: — 50-60% of value at which the serviceability would be exceeded; or — 110% of value predicted in design – accounting for design prediction with acceptable deviation that is still considered by the designer to be within the acceptable range. Note: predicted in design (normally) means prognosis, i.e. calculations with best-estimate-values for ground properties and with characteristics loads. An example of selecting a limiting value for the red level may include considering: — 90% of value at which the serviceability would be exceeded; or — 130% of value predicted in design. In cases where predicted values are close to the serviceability criteria, usually the latter should be used as a reference point for acceptance. However, when serviceability criteria are much higher than obtained design predictions or there is no clear basis for specification of those criteria, it is reasonable to relate the limits to the values of predicted performance of a structure. For example, when considering the lateral deflection of an embedded retaining wall supporting an existing building, limitation can be set based on allowable deformation to the building, whereas, in the absence of any structure within the influence zone, the limitations can be set on the basis of design predictions. However, if the trigger levels are selected on the basis of predicted behaviour of the structure, in some cases their value may need to be adjusted to the stage of construction, and they should be related to the predicted behaviour at that stage.

It is not possible to prescribe one set of levels that would universally fit all the design situations. The levels of the criteria will often depend on following factors: — If the impact of the negative performance can be reversed and at what relative effort and cost; — If there will be sufficient time to implement contingency measures and corrective actions; — How much margin of safety is needed to implement alternative design solutions. In general, a different approach should be implemented in situations where contingency measures can be implemented in time and where exceeding the specified criteria means that the structure would no longer be considered useable. 4.3 Guidelines on contingency measures Below are examples of actions that may be taken when specific trigger levels are exceeded: Breaching Green Trigger Review of measurements and trends Breaching Amber Trigger 1. Cross checking the readings of the instrument with another method (sanity check) and another instrument. 2. Inspection of the assets in the vicinity where the breach has occurred for signs of unpredicted behaviour and/or evidence of distress to the existing assets. 3. Notify all relevant parties. 4. Assess if there is any imminent danger to the stability of the works or third-party assets and establishes the extent of the zone of danger. 5. Evaluation of information and undertaking any analysis required to understand the implications including trends and cause of movements to assess if further movement is likely to be induced. 6. Assess the risk of continuing construction. 7. Initiates re-design and remedial measures including agreeing additional support measures and installations sequences where required. Breaching Red Trigger 1. Immediately inspects the asset in the area where the breach has occurred for sign of change to the works and existing assets. 2. Place restriction on use of infrastructure including building. 3. Where necessary stop the work and make the site safe. 4. Instigate the action plan and incident management plans. 5. Inform the client.

4.4 Case studies Although each project is different and acceptance criteria should be established on a case-by-case basis, examples are presented below for some typical cases: embedded retaining wall, soil nails and ground anchors, as well as embankments and cuttings. 4.4.1 Embedded retaining wall Deep excavations supported by embedded retaining walls are among the most complex cases, where acceptance criteria have to be defined. This is mostly due to their common construction in urban areas, where risk to adjacent assets is one of the largest concern, as well as due to the number of structural elements involved. Figure 21 shows a sketch of typical arrangement of an embedded retaining wall in relation to necessary observations to be taken. Examples of acceptance criteria that can be established are summarised in Table 11. Figure 17. Typical embedded retaining wall sketch Source: Developed by the Authors

Table 11. Acceptance criteria for Embedded Retaining Wall example

n° Asset D Embedded retaining wall

Parameters Displacement (x, y, z) Tilt of the wall/ wall deflection

Limit Value

Information needed to establish limit value

Design requirements to meet limit value

Geotechnical ground model, loads, use of the area in front of the wall

Semi-empirical methods, numerical methods using finite elements, similar experience (for GC1)

SLS wall deflections, location of struts and props

Limit of deflections to check SLS crack widths

Monitoring type 3D targets Inclinometers, 3D targets, tiltmeters, tilt sensors

Monitoring

Location

Precision

In plan: centre of the wall and in elevation: along the depth of the excavation at the surface of the wall.

10% of the Limit Value

For cantilever

-

wall at the top of

the wall and for

anchored wall

along the depth

of the excavation

with toe

extending to the

level where no

deflection is

predicted.

A Building

Displacement (x,y,z) differential settlement, tilt and tensile strain

Baseline readings, distance from wall, type of foundation, loads, condition surveys, geotechnical ground model

2D or 3D numerical methods to determine settlement distribution

3D laser scan, 3D topographical survey, strain gauges, tiltmeters, tilt sensors

Vibrations

Sensitivity of the structure (type of structure, design drawings, condition/age of the structure), building

Selection of construction method and work sequence and estimation of vibrations

Vibration sensor and recorder

In plan: at the front and the side of the building, two row of vertical target at least for each side Elevation: at least two targets (to check the tilt) Closest to the building

1% of the Limit Value -

Frequency of measurement 1 per week and before & after each excavation stage

Contingency measures

Measures when amber trigger values are breached

Measures when red trigger values are breached

Increase monitoring, revisit design, additional propping, review of construction sequence, review of design assumptions

Stop construction. Backfilling Review design parameters and redesign

1 per week and before & after each excavation stage 1 per week and before & after each excavation stage

Increase monitoring, revisit design, additional propping, review of construction stages, creation of temporary berms, review of design assumptions Frequent monitoring revisit the design Additional struts review of construction sequences, review of design assumptions

Stop construction, detailed inspection of retaining wall to identify visible signs of distress, review of construction sequence including review of backfilling, introduce emergency support systems Stop construction Backfilling Revisit the design parameters and redesign Stabilize the building

-

Inspection of building

Inspection of

(opening of cracks/other building (opening

damage), review of

of cracks or other

design assumptions

damage), if not

any damage,

evaluation of new

n° Asset

Parameters

Base of excavation

Heave

B Ground

Surface

surface

settlement

(road/rail

or open

land)

E Anchors

Deformation at head

Limit Value

Information needed to establish limit value inspection (existing cracks etc. in building)

Design requirements to meet limit value due to construction method and comparing those to allowable vibrations.

Pore-water pressures beneath the base of the excavation, ground water level

Use of 2D or 3D analysis to determine vertical deformation

Monitoring type Extensometers, settlement plates Settlement markets, frequent visual inspection

Monitoring

Location

Precision

At the base of the excavation At ground surface close to excavation

Project design specifications, geotechnical soil parameters, type, size and capacity of the anchor used

3D Targets

10% of the anchors at anchor heads

1% of the Limit Value

Load in ground anchor

Anchor loads derived from retaining wall assessment, spacing and inclination of anchors

Tension calculated

Strain gauges attached to anchors, load pins, pressure cells installed

2-3% of the anchors. Load cells at anchor head

1% of the Limit Value

Frequency of measurement

Contingency measures

Measures when amber trigger values are breached

Measures when red trigger values are breached limit value. If damage visible, redesign.

1 per week and after casting permanent structure Daily during construction 1 per week and before & after each excavation stage 1 per week and before & after each excavation stage

Review of design assumptions. Review of dewatering

Implementation of stabilization technique

Review of construction sequence, review of other monitoring data e.g. inclinometers, tiltmeters, strain gauges Detail inspection of anchor system, including anchor plates, surrounding support element and anchors to identify visible signs of distress. If possible, redistribute load amongst neighbouring anchors to alleviate stress in breached anchor, introduce temporary support system, adjust construction sequence, reassess design assumptions Detail inspection of anchor system, including anchor plates, surrounding support element and anchors to

Halt construction activities, inspect anchors, retaining wall and surrounding structures, introduce emergency support systems such as additional bracing or shoring to prevent further movement. Install additional anchors Halt construction activities, inspect anchors, retaining wall and surrounding

n° Asset

Parameters

Limit Value

Information needed to establish limit value

Design requirements to meet limit value

Monitoring type in the grout or behind the anchor head to measure pressure exerted by the anchor on the surrounding medium, load cells

Monitoring

Location

Precision

F Strut C Utilities

Strain, temperature, load

Load to carry, length, position, inclination

Displacement, Strain

distance from the wall, depth, type

Source: Developed by the Authors

finite elements or beam on spring +empirical method (Clough and O'Rourke, Bowles, Hsieh &Ou)

Strain gauge, Load cells, pressure cells, extensometers Topographic survey

Frequency of measurement

Contingency measures

Measures when amber trigger values are breached identify visible signs of distress. If possible, redistribute load amongst neighbouring anchors to alleviate stress in breached anchor, introduce temporary support system, adjust construction sequence, reassess design assumptions

Measures when red trigger values are breached structures, introduce emergency support systems such as additional bracing or shoring to prevent further movement. Install additional anchors

4.4.2 Soil nails and ground anchors An example of typical arrangement of a slope supported by soil nailing and ground anchors is presented in Figure 22. Potential acceptance criteria for such geotechnical structures are presented in Table 12. Figure 18. Typical soil nail and ground anchors arrangement Source: Developed by the Authors

Table 12. Acceptance criteria for Soil Nail and Ground Anchor example

n° Asset

Parameters

Limit Value

Information needed to establish limit value

Design requirements to meet limit value

Monitoring type

Monitoring

Location

Precision

Frequency of measurement

A Soil nail/anchors

Corrosion Stresses in anchors Movement / deformation

Soil composition, ground water chemistry, presence of corrosive agents Results of geotechnical design and characteristic properties of steel rod (anchors) Geotechnical ground model, loads, use of the area in front of the wall)

Material selection, protective coatings, cathodic protection, establishing a design life expectancy for the soil nail or anchor, corrosion allowance Capacity of the anchor GC3: Numerical methods implementing nonlinear stress-strain relations for the soil; GC2: Semiempirical methods and numerical methods based on spring model;

Visual inspection of corrosion protection of accessible parts of anchor head, electromagnetic testing, small samples of similar material to be installed in close proximity to the structure Strain gauge or load cell Inclinometers, 3D topographical markers

Fixed to the anchors Face plate or concrete structure

During the work, depending on the type of structure

Contingency measures

Measures when amber trigger values are breached

Measures when red trigger values are breached

Inspection of the embankment or cutting for visible signs of failure, review of design assumptions Frequent monitoring revisit the design Review of construction sequences

Stop construction Backfill Revisit the design parameters and redesign Stop construction Backfilling Revisit the design parameters and redesign

n° Asset B Embankment

Parameters Rupture of grout Ground Movement / deformation Lateral movement

Limit Value

Information needed to establish limit value

Design requirements to meet limit value

Pull out test / Sacrificial test

Traditional ULS calculation

Composition of embankment material, geological formation of the foundation of embankment, ground water level, seasonal variation, change in use of embankment

Monitoring type Monitoring the displacement of the head Surface crack monitoring using visual surveys, settlement markers (settlement pins or 3D target), piezometers, rainfall and weather stations, use of LiDAR, satellite imagery, acoustic emission monitoring, vibration monitoring Inclinometers/3D markers

Monitoring

Location

Precision

Head of anchor or soil nail or connected structure

Inclinometers to be placed at crest, roe & midslope, key transition zone where soil type or slope angle changes, areas prone to slippage with history of instability

Frequency of measurement Only during pull out testing, if connected to a structure then it should be in accordance with monitoring of the structure Weekly/monthly

Contingency measures

Measures when amber trigger values are breached

Measures when red trigger values are breached

n° Asset

Parameters

C Retaining

Tilt

structure

Horizontal movement (sliding) Source: Developed by the Authors

Limit Value

Information needed to establish limit value

Design requirements to meet limit value

Monitoring type

Monitoring

Location

Precision

Frequency of measurement

Results of global stability analysis of retaining structure, surcharge loading, ground water level, drainage behind the structure

Design loads, soil pressure, water pressure, effective drainage system to mitigate hydrostatic pressures behind the wall, backfill material, material properties. Establish deformation limits

Tiltmeter / 3D prisms, inclinometers behind the wall

On the face of the retaining structure

Weekly / monthly

Results of global stability analysis, drainage behind the wall, ground water level

Inclinometers/3D markers

At the toe of the structure

Weekly / monthly

Contingency measures

Measures when amber trigger values are breached Increase monitoring, revisit design, additional propping, review of construction sequence, review of design assumptions

Measures when red trigger values are breached Stop construction, detailed inspection of retaining wall to identify visible signs of distress, review of construction sequence including review of backfilling, introduce emergency support systems

Review of design assumptions, introduce temporary support system e.g. installation of anchors, driving a sheetpile in front of the wall

Halt construction and review design assumptions & construction sequence

4.4.3 Embankments and cuttings Examples of typical arrangement of a cutting and an embankment are presented in Figure 23. Potential acceptance criteria for such geotechnical structures are presented in Table 13. Figure 19. Typical embankment and cutting example Source: Developed by the Authors

Table 13. Acceptance criteria for Embankment and Cuttings example

n° Asset A Embankme nt/ Cuttings  

Parameters Settlement of embankments due to sub surface features including mine workings.

Limit Value

Information needed to establish limit value Historical information, mining risk assessment

Design requirements to meet limit value Is design criterion ULS or SLS ?

Monitoring type Settlement markers/ inclinometers/ pore water pressure

Monitoring

Location

Precisio n

Toe and crest

Ground movement / deformation due to; -Shrink & swell -Heave due to unloading in cuttings -dissipation of excess pore water pressure

Composition of embankment material, geological formation of the foundation of embankment, ground water level, moisture content in soil, historical data (records of ground movements or deformation at the site) slope geometry, seasonal variation, change in use of embankment, load acting at crest of cuttings and embankments, baseline monitoring data

Surface crack monitoring using visual surveys, Settlement markers (settlement pins or 3D target), piezometers, rainfall and weather stations, use of LiDAR, satellite imagery, acoustic emission monitoring, vibration monitoring

Inclinometers to be placed at crest, toe and midslope, key transition zone where soil type or slope angle changes, areas prone to slippage with history of instability, settlement markers on surface, for heave at base of the cutting

Frequency of measurement Before construction: monthly, during construction: daily, after construction: daily or weekly depending on trigger levels Weekly/monthly, continuous, or real-time monitoring system in critical areas for immediate detection of changes

Contingency measures

Measures when amber trigger values are breached

Measures when red trigger values are breached

If slope instability is detected, undertake measures such as grading, terracing or soil reinforcement to prevent further movement, drainage enhancement, monitoring system calibration, review design parameters, develop emergency response plan, establish a routine schedule for periodic inspection

Suspend operation of rail or highway on embankment and in cuttings, activate emergency response plan, detailed visual inspection, implementation of temporary stabilization measures which includes installing retaining structures, reinforcing critical points.

n° Asset

Parameters

B Rail or Highway

Displacement (x,y,z)

infrastruct differential

ure

settlement,

track

geometry

measurement

Vibrations

C OLE

Settlement of

foundation foundations,

&

tilts of

catenary, Catenary

Signal

mast using

foundation tiltmeters.

s, gantries

Source: Developed by the Authors

Limit Value

Information needed to establish limit value

Design requirements to meet limit value

Monitoring type Visual inspection, surface settlement marker (3D target), remote sensing

Geo-phones, accelerometers, seismometers

Permissible deflection limits of catenary mast as per standards.

Settlement markers/tiltmeter / targets for topographical survey.

Monitoring

Location

Precisio n

Toe and crest

Toe and crest near the track and at specific locations such as track junctions, curves. Settlement measurement at the base of the mast, tilt along the height of the mast structure.

Frequency of measurement Weekly / monthly Continuous monitoring during operations Weekly / monthly

Contingency measures

Measures when amber trigger values are breached

Measures when red trigger values are breached

Review of construction methods

5 Implementation of Design and use of Execution Standards 5.1 General The execution standards for specialist geotechnical works are a series of companion documents to cover the construction phase of the project. The concept is that such works would have been designed using the current versions of EN1990, EN1997, and other associated design codes. The execution standards are reviewed on a 5-year rolling basis, though revisions do not always result. As a consequence, it is the responsibility of the project team to ensure that the most recent version is being used or referenced in contract documentation. 5.2 Interaction between design and execution standards There is overlapping content within the design codes and execution standards with each covering aspects that are more normally considered to be the remit of the other. It is important to ensure that when reviewing the design content of the execution standards, or items relating to construction within the design codes, an appropriate weighting is given to the topic, in relation to the overall theme of the document. The design references within the execution standards have mostly been removed, where appropriate. Where some still remain, it is expected that these will be reviewed, and a decision taken on whether to remove or amend the standard, as a part of the process of systematic reviews. EN1997 would normally set precedent on purely design matters though there are issues which have both a design and an execution aspect to them (e.g. concrete cover), and both sets of documents need to be considered. The execution standards have been written with input from industry to ensure that they are in line with current practice. It is important to ensure that the designer does not specify items that conflict with the execution standards as this could compromise the quality of the final product or create problems with the process of construction. If conflicts are identified for specific project, they should be discussed between the design and execution teams to ensure the best outcome for the project – ensure that design intent is achieved without specifying methods that compromise execution.

6 Conclusions The second generation of EN1997 places a clear requirement on the designer to consider the implementation of the design in execution and not to focus only on the analysis and verification of limit states. To this end there are a series of plans required to be produced by the designer to help manage this process, and to achieve the expected level of quality assurance, appropriate to the potential consequences and complexity of ground-structure interaction. For this purpose, EN1997 sets general rules to be followed. However, it is recognised that more specific guidance and examples are useful to foster the implementation of those rules in national practices and to better understand the intent behind the requirements and recommendations presented in the code. This document aims to give guidance to the designer on how to meet the requirements placed on them in the design codes, whilst respecting the practicalities of the construction of special geotechnical works, as reflected in the execution standards.

References Dunnicliff, J., Geotechnical Instrumentation for monitoring field performance, John Wiley &: Sons, New York, 1988 ISBN: 978-0-471-00546-9 ICE - Institution of Civil Engineers, Specification for Piling and Embedded Retaining Walls, 3rd Edition, ICE Publishing, London, 2017 Royal Institute of British Architects (RIBA) Plan of Work, 2020 German Geotechnical Society, EA-Pfahle, Recommendations on Piling, 2013 EN1536 Execution standard for special geotechnical works - Bored piles JRC (2024). Assembling the Ground Model and the derived values. Guidelines for the application of the 2nd Generation of Eurocode 7 – Geotechnical design. Joint Research Council (JRC) of the European Commission, 2024 (to be published) JRC (2024). Determination of representative values from derived values for verification of limit states with EN 1997. Guidelines for the application of the 2nd Generation of Eurocode 7 – Geotechnical design. Joint Research Council (JRC) of the European Commission, 2024 (to be published) JRC (2024). Reliability-based verification of limit states for geotechnical structures. Guidelines for the application of the 2nd Generation of Eurocode 7 – Geotechnical design. Joint Research Council (JRC) of the European Commission, 2024 (to be published)

List of abbreviations and definitions

Abbreviations

Definitions

ABS ACE AIA APM BIM CC CPT GBR GC GCC GCR GDR GIR GR GW HOAI OLE LTP NATSPEC NZCIC RI RIBA SLS UCS ULS ZOI

Acrylonitrile Butadiene Styrene (thermoplastic polymer) Association for Consultancy and Engineering American Institute of Architects Association for Project Management Building Information Model Consequence Class Cone Penetration Test Geotechnical Baseline Report Geotechnical Category Geotechnical Complexity Class Geotechnical Construction Record Geotechnical Design Report Ground Investigation Report Geosynthetic reinforcement Groundwater Honorarordnung für Architekten und Ingenieurs Overhead Line Equipment Load Transfer Platform National Building Specification New Zealand Construction Industry Council Rigid Inclusions Royal Institute of British Architects Serviceability Limit State Unconfined Compressive Strength Ultimate Limit State Zone of Influence

List of figures Figure 1. RIBA Stages and potential relevance of EN1997-1 cl.10.1 Implementation of Design ...... 17 Figure 2. Project phasing sequence including the preparation of documents for a “typical” project 18 Figure 3. Checklist for Implementation of Design related to project stage .................................................... 19 Figure 4. Case study 1 cross section ..................................................................................................................................... 30 Figure 5. Elements of supervision ........................................................................................................................................... 31 Figure 6. Elements of inspection.............................................................................................................................................. 32 Figure 7. Elements of monitoring ............................................................................................................................................ 33 Figure 8. Plan view of pad foundation.................................................................................................................................. 36 Figure 9. Cross section A-A. Sectional view of pad foundation.............................................................................. 36 Figure 10. Cross section B-B. Sectional view of pad foundation........................................................................... 37 Figure 12. Geometry and data of the example............................................................................................................... 42 Figure 13. Base reinforcement under embankment example ................................................................................ 45 Figure 14. Base reinforcement under embankment example ................................................................................ 46 Figure 15. Example of monitoring arrangement ............................................................................................................ 49 Figure 16. Tanks and rigid inclusion layout ....................................................................................................................... 50 Figure 17. Tanks and rigid inclusion cross section ........................................................................................................ 50 Figure 18. Illustration of the example of ground water control through dewatering ............................... 53 Figure 19. Illustration of the “traffic light” model for limits.................................................................................... 58 Figure 20. Typical embedded retaining wall sketch ..................................................................................................... 61 Figure 21. Typical soil nail and ground anchors arrangement ............................................................................... 65 Figure 22. Typical embankment and cutting example ................................................................................................ 69

List of tables Table 1. Comparison of international plans of work..................................................................................................... 16 Table 2. Comparison of international plans of work..................................................................................................... 28 Table 3. Links to specific standards ....................................................................................................................................... 29 Table 4. Information relevant for Supervision and Inspection ................................................................................ 30 Table 5. Information relevant for Monitoring and Maintenance ............................................................................ 31 Table 6. Content of plans for supervision and inspection.......................................................................................... 37 Table 7. Plan for supervision, inspection, monitoring and maintenance ........................................................... 40 Table 8. Quality measures for bored piles during execution, based on EN1536, Table 8. ..................... 41 Table 9. Example content for the four plans..................................................................................................................... 43 Table 10. List of standards potentially relevant to groundwater control (based on example in section 3.8.2) ......................................................................................................................................................................................... 54 Table 11. Acceptance criteria for Embedded Retaining Wall example............................................................... 62 Table 12. Acceptance criteria for Soil Nail and Ground Anchor example ......................................................... 66 Table 13. Acceptance criteria for Embankment and Cuttings example............................................................. 70

Annexes

Annex 1. Example checklists for plans

Checklist: Spread foundation

Project Information

Project number

Project

Subject

Remarks

Procedure 1 General requirements 2 Supervision 3 Inspection 4 Monitoring 5 Maintenance Item

Related codes

- EN 1990

- EN 1991

- EN 1992

- EN 1997-1, EN 1997-3

- EN 13670:2013 Execution of concrete structures

General requirements

N.A.

Check

Value

Remarks

Consequence class

Geotechnical complexity class

Geotechnical category 78

Allowable absolute settlement Allowable differential settlement Other structures within zone of influence? Design service life General remarks

Item

Supervision

N.A.

Check

Value

Remarks

Dimensions as per project design?

Implementation tolerances in accordance with design?

Steel reinforcement placing as per with design?

Any coatings are as per design?

Material certificates for steel reinforcement meet specification?

Concrete mix design meets to design exposure class?

Base of excavation compact & dry before placing reinforcement and concrete? General remarks

Item

N.A.

Ground model: are the soils at the base of the excavation as per design assumptions?

Frost protection respected?

Excavation sides stable or require temporary works?

If backfill used, is compaction to specification?

General remarks

Inspection

Check

Value

Remarks

Item

Monitoring

N.A.

Check

Value

Remarks

General remarks General remarks

Often not required. May be required for GC3 structures such as bridges or large machine bases. Maintenance Often not required. May be required for GC3 structures such as bridges or large machine bases.

Checklist: Embankment Project number Project Subject Remarks

Project Information

Procedure 1 General requirements 2 Supervision

Related codes - EN 1997-1, EN 1997-3 - EN 16907-2, EN 16907-3, EN 16907-5

3 Inspection 4 Monitoring 5 Maintenance Item

- EN 16907-2, EN 16907-5, EN ISO 17892 Parts 5,9,10

- EN-ISO 18674 parts 1-5

- local guidelines

General requirements

N.A.

Check

Value

Remarks

Consequence class

Geotechnical complexity class

Geotechnical category

Allowable absolute settlement

Allowable differential settlement

Other structures within zone of influence?

Design service life

General remarks

Item

Supervision

N.A.

Check

Value

Remarks

Construction stages in line with project design?

Execution of earthworks to EN16907-3? Filling & compacting to EN16907-3 and EN16907-5? Stage duration in line with project design? General remarks

Item

N.A.

Are materials to specification, with documented proof?

Materials for each layer to EN169072?

Materials properties for each layer to EN16907-2?

Is friction angle of embankment material verified? Is this to project specification?

Has elastic modulus of embankment material been determined? Is this to project requirements?

Has relative density of embankment material been determined? Is this to project requirements?

Inspection

Check

Value

Remarks

Was stiffness & bearing capacity of subsoil checked? Is this to EN169075 and project requirements? Was quality of drainage system checked? Have other works been carried out which could provide extra data on the ground model? Is subsoil homogenous, or are there areas of variation? General remarks

Item

Monitoring

N.A.

Check

Value

Remarks

Monitoring installed top project requirements?

Baseline readings taken & instrumentation working?

Instrumentation to EN-ISO 18674 series?

Are expected physical readings defined?

Are timesteps for readings known?

General remarks General remarks

In the simple embankment case, no monitoring is usually needed. When weak subsoils are present, monitoring becomes necessary. Maintenance The maintenance of embankments structures is limited in practice. In most cases there are no reference documents for the topic. This will need to be agreed between the parties prior to the project design & implementation.

Checklist: Groundwater Control Project number Project Subject Remarks

Project Information

Procedure 1 General requirements 2 Supervision 3 Inspection 4 Monitoring 5 Maintenance Item

Related codes

- EN 1990

- EN 1991

- EN 1992

- EN 1997-1, EN 1997-3

-

General requirements

N.A.

Check

Value

Remarks

Consequence class

Geotechnical complexity class

Geotechnical category

Other structures within zone of influence?

Design service life

General remarks

Item

Supervision

N.A.

Check

Value

Remarks

Correct installation of pumping or infiltration wells? Correct installation of monitoring wells or piezometers? Correct execution of procedure for reduction of hydraulic permeability? Execution of geohydraulic testing according to EN22282 Execution of reduction of hydraulic conductivity according to grouting EN 12715, jetgrouting EN12716 Execution of barriers according to EN1538- Diaphragm walls, EN12063-sheetpile walls Execution of deep mixing according to EN14679 Execution of vertical drainage according to EN15237 Execution to project specification?

General remarks

Item

Inspection

N.A.

Check

Value

Remarks

General principles

The characteristics of the groundwater system relevant for the geotechnical design and effects within the zone of influence shall be considered both before and after execution to ensure that the design is applicable. Relevant parameters include: hydraulic conductivity, transmissivity, storage coefficient, groundwater levels, groundwater pressure, aquifers, aquitards, hydraulic contact. Inspection can be performed by observation, measurement or testing

Groundwater levels comply with design assumptions

Effect of dewatering on groundwater levels/pressure within zone of influence

Effectiveness of groundwater control systems for dewatering for purpose of stability of slope or base of excavation or infiltration to reduce impact of dewatering/drainage

Chemical composition of groundwater in relation to design assumptions for durability

Robustness of groundwater control systems to maintain required levels

Verify that reduction in hydraulic conductivity matches design requirements Absence of flow ingress/egress and/or monitoring of groundwater levels on both side of the barrier/zone of reduced hydraulic conductivity General remarks

Item General principles

Monitoring

N.A.

Check

Value

Remarks

Groundwater levels and/or groundwater pressure shall be monitored prior, during and after groundwater control works and works affecting groundwater levels

Groundwater levels to be checked for compliance with design requirements

Groundwater levels, leakage rates & changes in water levels due to groundwater control measures

Pumping rates within expected volumes

Is discharge water showing changes in chemical composition or signs of fines

Ground surface settlement Settlement of structures within zone of influence Raised groundwater levels outside a barrier due to damming effects

General remarks

Item

Maintenance

N.A.

Check

Value

Remarks

General principles

The maintenance plan shall include objectives, types, frequency of activities required to ensure the structure can be used for its intended purpose without major repair during its design service life.

Check critical items of groundwater control system to ensure design requirements can be maintained

The objective type and frequency of post-execution inspection

Acceptance criteria for critical items of the groundwater control system

Activities if acceptance criteria is not fulfilled General remarks

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