Applied Geotechnics for Construction Projects, Volume 2 - Ammar Dhouib - E-Book

Applied Geotechnics for Construction Projects, Volume 2 E-Book

Ammar Dhouib

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Beschreibung

Geotechnical engineering is now a fundamental component of construction projects. The second volume of this book addresses the fundamental principles of soil mechanics and the role of water in geotechnical projects and assessments. Applied Geotechnics for Construction Projects 2 outlines the hydraulic properties of soils and the basic concepts of water in soil, detailing the principles of permeability measurement tests and giving concrete test cases, and then goes on to outline the basic notions of soil mechanics as applied in geotechnics: from consolidation to short- and long-term notions via the swelling phenomena of clayey soils, soil shear strength and slope stability. The third chapter presents a comprehensive overview of geotechnical expertise using examples of concrete projects either with or without damage in the context of geotechnical construction works. Each chapter of this second volume provides concrete examples of applications to real projects and the rules and lessons we must remember. The result is a combination of geotechnical expertise and lessons learned from experience, both of which are highly valuable in the field of applied geotechnics for construction projects.

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Contents

Cover

Dedication Page

Title Page

Copyright Page

Foreword

Entrepreneur’s Tribune: Geotechnics is at the Heart of Our Projects

Preface

Acknowledgments

Symbols and Notations

Introduction

Chapter 1. Soil Hydraulics: On-Site Water Tests

1.1. Water in the soil: basics

1.2. Darcy’s law

1.3. Generalization to flow networks

1.4. Flow forces

1.5. On-site measurement of soil permeabilities

1.6. Practical applications

1.7. References

Chapter 2. Fundamental Principles of Soil Mechanics

2.1. Short-term and long-term soil behaviors

2.2. Soil consolidation and settlement

2.3. Shear strength of soil

2.4. Swelling-shrinkage of clay soil

2.5. Slope stability

2.6. Conventional safety coefficients

2.7. Applications

2.8. References

Chapter 3. Geotechnical Expertise

3.1. Preamble

3.2. Expertise on actual project cases

3.3. Judicial expertise

3.4. Examples of rehabilitation (load balance)

3.5. Conclusion

3.6. References

French, European and ISO Standards in the Field of Geotechnics

Index

Summary of Volume 1

Summary of Volume 3

Summary of Volume 4

Other titles from iSTE in Civil Engineering and Geomechanics

Wiley End User License Agreement

List of Illustrations

Chapter 1

Figure 1.1.

Condition of liquid continuity (flowing water)

Figure 1.2.

Water velocity in soil

Figure 1.3.

Head of water in a given reference plane

Figure 1.4.

Water flow in soil

Figure 1.5.

Calculation of the permeability coefficients in stratified soil

Figure 1.6.

Two-dimensional flow network

Figure 1.7.

Limiting conditions in an earthen dam

Figure 1.8.

Flow forces acting on a basic volume of soil

Figure 1.9.

Evolution of pore pressures during the construction of an embankment

Figure 1.10.

Principle of the pumping test

Figure 1.11.

Lefranc test: principle and experimental set-up

Figure 1.12.

Variation of form factor m. For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 1.13(a).

Lugeon test: principle and measuring device

Figure 1.13(b).

Typical section and schematic layout of the well and piezometers

Figure 1.14.

Preliminary step-wise pumping: drawdown (s) as a function of the flow rate Q (Dhouib 2005)

Figure 1.15.

Characteristic curve of the well: unit drawdown s/Q as a function of the flow rate (Dhouib 2005)

Figure 1.16.

Drawdown s in the well as a function of log t time (Dhouib 2005)

Figure 1.17.

Piezometric drawdown in relation to the axis of the well (Dhouib 2005)

Figure 1.18.

Calibration on the experimental curve of the head of water in marl-limestone from Saint-Ouen (Dhouib

et al.

1998). For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 1.19.

Calibration in semi-logarithmic coordinates for a test in the limestone of Saint-Ouen (Dhouib

et al.

1998). For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 1.20.

Calibration from the differential equation for a test in Saint-Ouen limestone (Dhouib

et al.

1998). For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 1.21.

Example of a Lugeon test in the body of a masonry foundation (Dhouib 2005). For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 1.22.

Permeability of soils. For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 1.23.

Principle of laying piezometric tubes and site photos. For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 1.24.

Measurements of vertical velocities, estimation of flow rates and permeability at the micro-reel: real case of sandblasting bilayers. For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Chapter 2

Figure 2.1.

Concept of friction and cohesion in soil. For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 2.2.

Unsustainable cohesion in sands and gravel-sand mixtures. For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 2.3.

Stresses and displacements of soil under the weight structures

Figure 2.4.

Mechanical analogy: steps of progressive transfer of loads (consolidation diagram). For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 2.5.

Oedometric conditions and soil consolidation over time. For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 2.6.

Results of an oedometric test on clay silt. For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 2.7.

Consolidation curve in an oedometer creep test on silts. For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 2.8.

Consolidation of a layer of fine soil (clay) drained on both sides. For a color version of this figure, see www.iste. co.uk/dhouib/geotechnics2.zip

Figure 2.9.

Compressibility of fine soil according to its state of consolidation. For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 2.10.

Settlement curves of fine compressible soil

Figure 2.11.

Degrees of consolidation as a function of the time factor T

v

and T

r

. For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 2.12.

Shear stress and soil failure. For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 2.13.

Soil shear strength

Figure 2.14.

Shear stress and intrinsic curve (C) at the triaxial test. For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 2.15.

Shear strength of granular soil (sands, gravels)

Figure 2.16.

Unconsolidated – Undrained (UU) test: envelope curves

Figure 2.17.

Consolidated – undrained test with measurement of pore pressures u: CU + u. For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 2.18.

Shear strength of soil by consolidated-drained (CD) Test

Figure 2.19.

Corresponding states theorem

Figure 2.20.

Swelling mechanism: swelling pressure. For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 2.21.

Variations and correlations between swelling-shrinkage parameters (Dhouib

et al.

2002b). For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 2.22.

Swelling-shrinkage tests: evaluation of the two phenomena

Figure 2.23A.

Solutions for underpinning and protecting foundations against water variations and tree roots

Figure 2.23B.

Injections (chemical and lime) in the United States (Hayward Baker 1998). For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 2.24.

Slip modes of soils on slopes and in excavations

Figure 2.25.

Failure mechanism: plane slip

Figure 2.26.

Failure mechanism: circular slip

Figure 2.27.

Failure mechanism: plane slip in granular soil

Figure 2.28.

Failure mechanism: circular slip

Figure 2.29.

Embankment on soft and compressible undrained cohesive soil c

u

Figure 2.30.

Slope stability calculation principle. For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 2.31.

Force balance along the failure circle. For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 2.32.

Circular failure method

Figure 2.33.

Solutions for improving stability by draining water. For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 2.34.

Concept of safety coefficient F

Figure 2.35.

Results of on-site reconnaissance

Figure 2.36.

Stability study of granular soil (dense sand): unframed safety coefficients (trend toward “skin failure”, see Figure 2.27)

Figure 2.37.

Vane test of the soil under embankment. For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 2.38.

Study of an embankment on soft and compressible soil: profile studied and theoretical failure circle

Figure 2.39.

Correlations between compressibility parameters. For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 2.40(a).

Diagram of natural water content and compressibility

Figure 2.40(b).

Characterization of soils according to natural water content

(w) and compressibility rate C

c

/(1 + e

0

). For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 2.41.

Validity of measurements of compressibility parameters: OCR, N

SPT

and q

c

(CPT) for lagoon deposits and silt-clay alluvium

Figure 2.42.

Validity of compressibility parameters: measured pre-consolidation stress and correlations with c

u

(N

SPT

and q

c

) and corresponding OCR. For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 2.43.

Validity of compressibility parameters: OCR and pressuremeter data for compact clays

Figure 2.44.

Evolution of the effective angle of friction

φ

’ as a function of the % of passes at 2 μm

Figure 2.45.

Effective angle of friction (

φ

’) as a function of plasticity index I

P

Figure 2.46.

Triaxial test (CU + u) on soft marl. For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 2.47.

Intrinsic curve in a Mohr-Coulomb plane: determination of the effective shear parameters c’ and

φ

’. For a color version

of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 2.48.

Calibration with the triaxial test (CU + u). For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 2.49.

Stress paths and critical and failure state. For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 2.50.

Correlations and practical results of undrained cohesion (c

u

). For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 2.51.

Undrained cohesion cu as a function of the liquidity index I

L

and plasticity index I

P

. For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 2.52.

Ratio of undrained cohesion (c

u

) to effective vertical stress in soil (σ’

v0

) as a function of the liquidity index (I

L

) (Bjerrum and Simons 1960). For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 2.53.

Effective cohesion (c’) as a function of the consistency index I

c

. For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 2.54.

Correlation between water content and compressibility ratio. For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 2.55.

Shear characteristics of soil treated with lime and cement and used in railway technical embankments. For a color version of this

figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Chapter 3

Figure 3.1.

Summary of geo-mechanical data. For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 3.2.

Matching the future project to the existing one. For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 3.3.

Descent of loads on existing foundations and future foundations. For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 3.4.

Evolution of E

M

moduli and net limit pressures p

l

*. For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 3.5.

Resistance values and correlations between them for checking anomalies detected by the dynamic penetration tests. For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 3.6.

Insertion of the project into the geotechnical context of the site. For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 3.7.

Water heads in excavations and resulting flows. For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 3.8.

Permeability deduced from water heads in excavations. For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 3.9.

Water flows actually pumped over the entire excavation during the construction phase for 140 days. For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 3.10.

Geotechnical and hydrogeological context and insertion of the tower area and the central core. For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 3.11.

Mode of foundations of the tower and its central core in the pre-project phase (PPP). For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 3.12.

Analysis and correction of E

M

pressuremeter moduli for foundation justification calculations: general raft, slurry trench piles and isolated masses. For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 3.13.

Modeling of the various foundations in two dimensions. For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 3.14.

Field of displacements. For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 3.15.

Synthesis of settlements of the foundation raft and slurry trench piles. For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 3.16.

Elevation-section of a nailed wall profile modeled by “TALREN”. For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 3.17.

Characterization of the clay layer (“soap layer”). For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 3.18.

Characterization of the “soap layer” on the Casagrande diagram. For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 3.19.

Characterization of the “soap layer” in an I

P

-

φ

' diagram (Dhouib

et al.

2002b; Dhouib 2016). For a color version of

this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 3.20.

Calibration of the safety coefficient of the nailed wall – incidence of the clay layer (“soap layer”). For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 3.21.

Pressuremeter data in SP101 and SP102. For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 3.22.

Changes in pressuremeter parameters (E

M

and p

l

*) as a function of depth in SP101 and SP102. For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 3.23.

Photos of the excavations carried out and criteria of the existing strip foundations under the damaged pavilion. For a color version of

this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 3.24.

Water status and characterization of clay under strip foundations. For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 3.25.

Control of creep pressures. For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 3.26.

Analysis of soil creep under the existing continuous foundations of the damaged pavilion: creep factor F

f

. For a color version of this

figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 3.27.

Summary and wedging of the existing strip foundations of the damaged pavilion. For a color version of this figure,

see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 3.28.

Tracking the behavior of the damaged pavilion. For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 3.29.

Attenuation of surface vibration waves (from source

S

to target, distant from

R

). For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 3.30.

Attenuation of volume vibration waves (from source

S

to target, distant from

R

). For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 3.31.

Plan for identifying works and targets (riverside). For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 3.32.

Cross-section – elevation of the project and insertion in the topographic, geological and hydrogeological context. For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 3.33.

Incidence of vibration waves on riverside constructions represented by the different targets: C1 to C4. For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 3.34.

Examples of pumped water re-infiltration wells.

For a color version of this figure, see www.iste.co. uk/dhouib/geotechnics2.zip

Figure 3.35.

Foundations of the damaged store. For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 3.36.

Loads on the existing ones and future loads (after rehabilitation). For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 3.37.

Existing/future load balance resulting from rehabilitation. For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 3.38.

Comparison of existing/future stresses with q

SLS

soil. For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 3.39.

Industrial building transformed into a residential building. For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 3.40.

Terrain model and altimetric setting of the three piles: P3, P14 and P15.

For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

Figure 3.41.

Load comparison (existing/future and soil and concrete contribution). For a color version of this figure, see www.iste.co.uk/dhouib/geotechnics2.zip

List of Tables

Chapter 1

Table 1.1.

Range of variation of the permeability of soils and characteristic values in certain soil types

Chapter 2

Table 2.1.

Mechanical analogy of water/spring behavior and saturated fine soil

Table 2.2.

Order of magnitude of compressibility parameters measured with the oedometer in various soil

Table 2.3.

Assessment of soil compressibility

Table 2.4.

Compressibility and creep parameters measured in peat and peat clays in the Essonne valley

Table 2.5.

Order of magnitude of creep parameters measured in various organic soil (peat)

Table 2.6.

Value of the time factor T

v

according to the degree of consolidation U

Table 2.7.

Values of the (vertical) coefficient of consolidation c

v

for fine soil

Table 2.8.

Practical correlations between compressibility/creep parameters

Table 2.9.

Orders of magnitude of shear characteristics for various types of granular and cohesive soil (units in kPa and degrees)

Table 2.10.

Consistency range of clays (consistency index Ic) and consequences on swelling-shrinkage

Table 2.11.

Class of instability of clays with respect to swelling-shrinkage

Table 2.12.

Conventional values of partial weighting and safety coefficients for calculating the stability of slopes and deep excavations

Table 2.13.

Experimental data in different typical clays

Table 2.14.

Results of measurements in various typical kinds of fine soil

Chapter 3

Table 3.1.

Pressuremeter data in SP101 and SP102

Table 3.2.

Characterization measurements of green clay with respect to water status and swelling/shrinkage under the damaged pavilion

Table 3.3.

Balance of current loads on existing footings of the pavilion

Table 3.4.

Creep factors (Ff) under the strip foundations of the pavilion. For a color version of this table, see www.iste.co.uk/dhouib/geotechnics2.zip

Table 3.5.

Summary of data relating to the pavilion disaster

Guide

Cover Page

Dedication Page

Title Page

Copyright Page

Foreword

Entrepreneur’s Tribune: Geotechnics is at the Heart of Our Projects

Preface

Acknowledgments

Symbols and Notations

Introduction

Table of Contents

Begin Reading

French, European and ISO Standards in the Field of Geotechnics

Index

Summary of Volume 1

Summary of Volume 3

Summary of Volume 4

Other titles from iSTE in Civil Engineering and Geomechanics

Wiley End User License Agreement

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To my mother, Fatima Ezohra.

To Leïla-Marie, Michaël-Hassen,

To Hajer, Thérèse, Siwar, Catherine and Yannick.

To my brothers and sisters.

To all my friends

from Dieppe to Velaux,

from Tunis to Gabès.

This book is dedicated to the memory of my father Salem Dhouib, Hassen Ben El Hadj Salem Dhouib (my grandfather, the wise one), Hélène Dyerick-Urbanski (my second mother in France, the generous one), Pierre Bertin, the Oranais, my friend and brother always, and to Christiane Bertin-Guigues, friend and mother for eternity.

Series Editor

Gilles Pijaudier-Cabot

Applied Geotechnics for Construction Projects 2

Fundamental Principles of Soil Mechanics and the Role of Water

Ammar Dhouib

English edition first published 2022 in Great Britain and the United States by ISTE Ltd and John Wiley & Sons, Inc.

French edition published by Presses de l’École Nationale des Ponts et Chaussées, Paris, France 1st edition © Presses de l’École Nationale des Ponts et Chaussées 2016 2nd edition (revised and updated) © Presses de l’École Nationale des Ponts et Chaussées 2021

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Library of Congress Control Number: 2022941488

British Library Cataloguing-in-Publication DataA CIP record for this book is available from the British LibraryISBN 978-1-78630-776-7

Cover images: Photo 1 (background image): VINCI Construction Terrassement (VCT) earthworks site on a railway line. Photo by Pascal Le Doaré (supplied by photographer for a fee). Photo 2 (top center): Pont Jacques Chaban-Delmas vertical-lift bridge in Bordeaux, France. Photo by Richard Nourry (courtesy of photographer). Architect: Cabinet Lavigne (MM. Charles and Thomas Lavigne), Groupement entreprises (VINCI) – Representing Jean-François Roubinet. Project owner: Communauté Urbaine de Bordeaux (CUB). Photo 3 (middle right): Institut Gustave Baguer, Asnières sur Seine, France. Photo by Augusto da Silva (courtesy of photographer). Entreprise: GTM BATIMENT VINCI – Representing Jean-Yves Cojean, President. Photo 4 (bottom right): Pavilion of Michel and Camille Richaud, Velaux, France. Photo by the author. DR M. & Mme Richaud. Photo 5 (bottom center): Shielded trench with horizontal struts. Photo by the author. VINCI Construction France site (DR VCF). Photo 6 (bottom left): CMA Tower, Marseille, France. Photo by Govin Sorel (courtesy of photographer). Architect: Zaha Hadid.

Foreword

This book is the work of a practicing engineer who has spent more than 30 years in the field of geotechnics applied to construction works. It is therefore already the result of a whole range of experiences, made up of numerous studies and works, as well as research, university chairs and publications in this discipline.

Ammar Dhouib, who received his doctorate in soil mechanics from the University of Lille in 1987, has since acquired extensive experience from design offices and companies specializing in geotechnics (Terrasol, Fondasol, Louis- Ménard, Solen and Keller Fondations Spéciales). He is currently chief engineer and geotechnical expert at VINCI Construction France, assisting and consulting for subsidiaries of the VINCI Construction group.

In addition to all of the studies he has carried out for foundations or other geotechnical works, he is also known for having jointly published a book in 2004 with Jean-Pierre Magnan and Philippe Mestat, on the improvement of soils in situ and another book in 2005 with Francis Blondeau, on stone columns.

The present work by Ammar Dhouib has the advantage of being both comprehensive and detailed while remaining quite traditional in its presentation. It includes 12 chapters ranging from the definition of soils, their surveys and the determination of geotechnical parameters to the design of structures (foundations and retaining walls in particular, tunnels do not come under such scrutiny). It is worth noting that there is an important chapter devoted to the effects of water in soils, which we know can lead to damage and failure when not all aspects of a geotechnical structure have been properly studied. As for the chapter on soil improvement, it was only natural that it should be included, given both the author’s knowledge in this field and the importance that this aspect now has in the foundations of construction works.

This book also presents very instructive elements for all those interested in geotechnics. These are the practical applications and examples given at the end of each chapter to illustrate and explain the principles, as well as the difficulty of geotechnical sizing. The author presents real cases that have been measured, which allow the sizing to be compared with reality.

This method is not new, it is the so-called “observational method”, generally reserved for complex or large structures, for which it is necessary to avoid any disruption. The author also shows cases of excessive deformations, or even the beginnings of failure in structures and gives the causes.

Ammar Dhouib’s book therefore appears to us to be of interest to a wide range of geotechnical scientists, from students to qualified engineers, including building owners, project managers and court experts.

Philippe GUILLERMAIN†1 François SCHLOSSER

Notes

1

Philippe suddenly passed away on May 7, 2016, without being able to attend the presentation ceremony of the first edition of the book on September 16, 2016, at the FNTP.

Entrepreneur’s TribuneGeotechnics is at the Heart of Our Projects

“Geotechnics is at the heart of our projects” – is this just an idea or an irreversible “truth” of the moment? It is indeed the current “reality” because, nowadays, “good” soils are becoming rare, projects are more complex and regulations are more developed.

Good sites are rare. Between industrial wastelands and marshy grounds, the soil is often aquiferous, soft or compressible, and its significant deformations under the weight of the works often become, in this context, incompatible with the allowable displacements of the structure.

The projects are complex, ranging from towers of several dozen or even several hundred meters in height, sometimes located in the middle of sensitive existing structures, to deep excavations (70 m for the open excavation of the ODEON tower in Monaco), bridges in aquatic sites (Normandy Bridge in France, Charílaos Trikoúpis Bridge in Rion Antirion Greece) and tunnels in soft soils and sensitive urban environments (the tunnel under the city of Toulon is a perfect example).

Regulations have undergone considerable development and are becoming more and more demanding because of the new French and European standards, such as the standardized geotechnical missions and the “Eurocodes”.

Limiting ourselves to sizing the foundations within this framework, both with rigor and common sense, is no longer sufficient in the face of today’s requirements of quality, conformity and respect for deadlines and budget, on the one hand, and safety and environmental imperatives on the other hand.

The geotechnical engineer must think of alternative foundation solutions, size them and optimize them with four points in mind: to ensure the quality, solidity, stability and durability of the structure. The geotechnical engineer will seek substantial savings on the foundations for the company and the client, and will be concerned with societal and sustainable development criteria.

This book is dedicated to students, engineers in design offices and companies, legal experts in geotechnics, insurers and financiers. It exposes the fundamental bases of soil mechanics, and illustrates and develops practical examples in the fields of geotechnics, in the broadest sense. In these fields, the geotechnical engineer can propose, study and justify foundation variants by replacing, for example, piles by soil improvement, in order to make the best use of the properties of the ground, and therefore of natural resources. The man of art will propose alternative design solutions to retain structures and ensure the stability of the excavations and existing constructions. These alternative solutions are calculated, optimized and justified by various approaches of analytical calculations and numerical modeling in deformation, which are undergoing major developments. The geotechnical engineer must also understand better risk management, whether related to soil defects or to the new requirements of modern projects.

Pascal LEMOINEEric DURAND

Preface

In the foreword to this book, Pascal Lemoine of the Fédération Nationale des Travaux Publics (French National Federation of Public Works, FNTP) and Eric Durand of the Fédération Française du Bâtiment (French Building Federation, FFB) wrote: “Geotechnics is at the heart of our projects”!

The term “Geotechnics” is new, but geotechnics itself is not, as our ancestors have always known how to “integrate” soil and foundations together in order to build bridges to cross rivers, roads to bring cities closer together, dams to irrigate plains and buildings to house the peoples of Africa, the Americas, Asia, Europe and Oceania.

Without looking in the “Grand Larousse” or the “Petit Robert”1, geotechnics can have many definitions and is based on many rules. We happily acknowledge some of them:

– Geotechnics is a “marriage” between soil and foundation; this marriage can only be successful when the soil is “healthy” and in good condition, and the foundation is not overly constraining, so as to ensure the quality, solidity, stability and durability of the structure.

– Like medicine, geotechnics requires targeted and adapted investigations, where the soil must be examined well and carefully identified geologically, and mechanically characterized well. The geotechnical engineer can then establish an accurate diagnosis and suggest basic rules to design and size their project, like a doctor who issues a prescription in order to cure their patient.

– Geotechnics is directly related to the place where the geotechnical engineer is located, like the farmer who loves their land, meditates on it, ploughs it and sows it. The engineer is attached to their projects to establish them in the ground, while seeking to optimize the foundations of their project, keeping in mind the safety of the men and women during construction (the work phase), the stability and durability of the work over time and the safety of people who will live there from far or near (the service phase).

– Geotechnics is not an exact science; it resembles the art of “cooking”, a very refined and elaborate cooking, rich enough to be the most beautiful of practical sciences that allow engineers to excel over time, like how soil strengthens by “aging” and how cooks become real “chefs” after trying many recipes, concocting new dishes and serving many meals.

That being said, there is no geotechnics without soil mechanics, continuous media mechanics and resistance of materials. Like human beings, soil is very complicated and complex, in other words, “vicious”2, because:

– soil has many parameters to be identified, recognized and classified: its moisture content, plasticity, grain size and surrounding voids, compressibility, creep, cohesion and friction;

– soil has several behaviors: inelastic, viscoelastic, plastic, dilatant and contracting, swelling and shrinking and subject to creep over time under constant stress;

– it is sensitive to the water that circulates within it and to external agents (chemical aggression, frost and water circulation) that can destabilize its structure (gullying and collapse) and cause it to evolve over time (swelling, shrinking and creep);

– the soil is subject to all kinds of anomalies. Natural anomalies include pockets of dissolution (e.g. gypsum, which dissolves like sugar

3

), karsts, “collapsible”

4

soils, etc. Examples of artificial anomalies are underground quarries, marl pits in Normandy, catiches in the North of France and so on.

Through studies and the elaboration of projects, university chairs, conferences and national and international congresses, we noticed that practicing engineers, students, pupil-engineers, beginners and even young experienced engineers have difficulty in understanding the meaning of geotechnical parameters. They do not master the methods which are used to determine these parameters, nor the way to use them in simple methods of calculation and dimensioning. They have not mastered how to introduce them in more complex models using, for example, modeling and calculations in finite elements (“CESAR-LCPC”, “FLAC-3D” and “PLAXIS”), in finite differences, by the boundary method, or even in software of traditional rupture calculation like “TALREN”, or in retaining structures software based on the principle of the coefficient of reaction like “RIDO”, “PAROI”, “DENEBOLA-LCPC” or “k-Réa”. Some young people, with their infatuation with computers, have good mastery of computer software and great speed in building complex geometric models, and use results that are sometimes erroneous because of a bad choice of parameters or the models are inadequate to accurately describe and follow the behavior of the soil, which can indeed be very difficult, very complex and very “vicious”.

Works dealing with geotechnics are relatively numerous in France. The four volumes of this book constitute, first and foremost, a practical and useful guide for beginners or experienced engineers, for students and student-engineers, for project managers and for insurance and justice experts specialized in Geotechnics: Section C125-SOL (soil).

Resulting from conferences in national and international congresses and symposiums, at multiple university chairs of its author, at the Ecoles polytechniques de Lille, d’Orléans et de Paris Sorbonne (Polytechnic Schools of Lille, Orleans and Paris Sorbonne), at the Ecole centrale de Lille (Central School of Lille), at the Ecole Nationale des Ingénieurs de Tunis (Higher National Engineering School of Tunis, ENIT) and the universities of Tunis, at the Hassania School in Casablanca, Morocco, and at the Ecole Nationale des Ponts et Chaussées in Paris, this book in four volumes is largely enriched by several practical applications, generally resulting from concrete projects studied by the author and his collaborators and/or his students in end-of-study works, from TERRASOL, via FONDASOL and SOLEN, to VINCI. Applications and projects are marked by the the author’s own practical experience, since 2007, of judicial expertise before judicial and administrative courts.

Developed between 2008 and 2021, and then taken up again before being further enriched by a specific chapter related to Geotechnical Expertise for its re-edition, this book in four volumes is articulated in four main themes:

– Definition of the soil, choice of the geotechnical parameters and methods of their determination, mainly from tests and investigations on site, and incidentally from laboratory tests.

– Fundamental relations and laws of soil behavior, ranging from elastoplasticity (simplistic hypothesis because the soil is not elastic) to soil creep, making it possible to understand the formulations introduced in the calculation and numerical modeling software that continues to develop in the field of “modern” geotechnics.

– Applications to foundations, retaining structures, backfill and embankment, soil improvement and underground structure projects, with a reminder of the simple physical rules and an introduction to the various standards, references and rules in place: from the DTU, via the leaflets, to the Eurocodes; references are compared, analyzed and commented on, particularly in Volume 3,

Chapters 1

to

3

, which is dedicated to the foundations of construction projects.

– Feedback: by means of “what not to do” where, at the end of the chapter, as well as in the new

Chapter 3

in Volume 2, entitled “Geotechnical expertise”, some cases of litigation and claims due to several factors are presented: bad studies, unfinished or even erroneous design, lack of follow-up and control of the execution, bad execution, not to mention in some, fortunately relatively rare, cases encountered in particular in judicial expertise, “fraudulent execution (poor workmanship and/or non-execution)”.

First of all, we wanted to present all the geotechnical parameters involved in the calculation and dimensioning of structures, as well as simplify the basic principles and fundamental relations of soil mechanics, then to present and comment on an overview of practical project examples that is as complete as possible, in order to best cover the field of geotechnics applied to construction projects. This is a vast field that is both simple and complex, and is not simplified by the recent European codes, called “Eurocodes”, and the new national application standards (NAN) of Eurocode 7, which are deliberately only referred to in the applications in order to make using this book as easy as possible. We consider that a student, a beginner or even an experienced engineer, as well as a project manager or a building expert focused on geotechnics, will easily understand the meaning of a safety coefficient of 3 on the point and 2 on the skin friction when sizing a pile, before encountering Eurocode errors and the NAN of Eurocode 7 where “partial” weighting factors and “partial” safety coefficients are linked together, often without any basis. This complicates the approaches, methods and traditional references related to geotechnics.

After the edition and publication of the book on September 16, 2016 by the Presses de l’Ecole Nationale des Ponts et Chaussées, under the aegis of the FNTP and the IREX (Institute for Applied Research and Experimentation in Civil Engineering), the FFB, the Compagnie des Experts près de la Cour d’Appel de Versailles (Company of Experts at the Court of Appeal of Versailles, CECAV) and the Conseil Pont Formation, we have received feedback from various readers and users of the book, including observations and opinions that are, on the whole, very positive. We therefore considered it beneficial to re-edit the book, correcting a few “typos” and taking into account some very useful comments. Naturally, the new edition retains the entire framework of the book, but it includes several illustrations and enriches the appendices in almost every chapter.

Thus, at the request of some geotechnical colleagues from design offices and judicial and insurance experts, whose kind messages have delighted us, we have written and completed the book with a new chapter (Volume 2, Chapter 3) that is simple, rich and well-illustrated, entitled “Geotechnical Expertise”. The purpose of this detailed chapter is to:

– Present, analyze and comment on examples of concrete projects with or without disorder in the context of geotechnical construction projects, and how to search for simple foundation solutions with an objective of “economic realism”.

– Define the bases and focus of the geotechnical expertise ordered by a competent court (known as “judicial expertise”) and the role of the geotechnical expert appointed by this same court, formerly called the “judicial expert” and more recently the “justice expert”.

– Conclude with some general geotechnical information, lessons and rules to remember.

Volume 2, Chapter 3 is intended to enrich and give the book a truly practical aspect. It is a repository for feedback from daily geotechnical work and expertise that deserves to be exposed to the young engineers and geotechnical experts of the current and future generations.

Contrary to the first version, each volume of the new edition concludes with an index in order to make the use of this book, and the search for technical information in the 12 chapters and 1,100 pages, easier and more convenient.

Notes

1

These are the two most well-respected French language dictionaries, the equivalent of the Merriam-Webster Dictionary and the Oxford English Dictionary.

2

The term “vicious soil” or “soil defect” is particularly used by judges and lawyers to designate an anomaly, a hazard, a “new fact” detected in the soil by the project actors. The term “defect” is often an argument put forward by lawyers to defend their clients in legal expertise in order to specify that, for example, the anomaly encountered in the soil is a hazard, and therefore a “defect” inherent in the soil.

3

Gypsum glows in the sun (

Figure 1.12

in Volume 1,

Chapter 1

) and dissolves in water within minutes like sugar, hence the term “saccaroid gypsum”.

4

“Collapsible” soils are a recent discovery in the big disaster (without end) of the Grand Littoral in Marseille where, following the collapse of the foundation piles, it was noted that the soils, applied under the same loading constraint, undergo deformations by the imbibition effect.

Acknowledgments

Our first thanks go to VINCI, in particular VINCI Construction France, its management and staff throughout France and around the world, who have enabled us to work, from the call for tender to the “turnkey” handover, on diverse and varied, and sometimes exceptional, projects with men and women who count.

The Entrepreneur’s Tribune, which introduces the book, testifies to the interest shown by the FNTP, represented by Pascal Lemoine, and the FFB, represented by Eric Durand, in the completion and publication of this work. To these two federations, pioneers of the construction industry in France, and to their representatives Pascal Lemoine and Eric Durand, we extend our sincere thanks.

The Compagnie des Experts près la Cour d’Appel de Versailles (Company of Experts at the Court of Appeal in Versailles, CECAV) has warmly accompanied us in the presentation of the book. We extend our deepest thanks to its president, Anne- Marie Pruvost-Paris, and to all of its members.

We would also like to thank Professor François Schlosser, our ENPC “Master” at TERRASOL since 1984, and Philippe Guillermain, our sponsor at the courts since 2007, for writing the preface for this book and enriching the text with their valuable advice.

Mr. Louis Demilecamps, former director of the Direction des Ressources Techniques et Développement Durable (Technical Resources and Sustainable Development Department, DRD) at VINCI Construction France, has encouraged us since 2008 and has energetically contributed to the publication of this book. We would like to send our warmest thanks.

A special thought goes out to Michel Khouri, who advised us for a long time to deepen the relations between soil and structure through the reinforcements to be introduced in the concrete of piles, footings, rafts and retaining walls.

Many people have contributed in one way or another through their end-of-studies work, internships and direct collaboration. We give our sincere thanks to all of them here: Cécilia Guibert, Sophie Jacquemin, Thomas Defoy, Olivier Payan, Grégoire Priol, Benjamin Leroi, Lina Bawji, Marilyse Dupraz, Sophie Lelièvre, Ludovic Boucaux, Anne Cotte, Isabelle Decker, Joan Mimica, Karim El Jouhari, Jihane Laboudi, Hélène Roulet, Fabienne Magnon, Laurence Oettli, Laurent Soyer, Bilge-Beryl Aksoy, Annouar Siala, Paul Lacrampe and Jese Andriamboavonjy.

ISTE’s translation, production and editing teams have shown great professionalism in the work accomplished in close collaboration and synergy with the author for the preparation of the four volumes of this book. The author would like to thank them very warmly and sincerely.

There are many warm and kind testimonies, spoken and/or written, received after the publication of the 2016 book. We would like to thank (in alphabetical order): Mr. Alba Jean-Michel (SOL-ESSAIS), Mr. Bataille Arnaud (ESIRIS), Mr. Brulé Stéphane (Ménard), Mr. Caporali Pascal (SOL CONSEIL), Mr. Delhomel Alain (SNCF), Mr. Fourmentraux Hugues (President of VINCI Construction France), Mr. Gallet de Saint-Aurain Jean-Marc (SEMOFI), Mr. Gambin Michel, Mr. Guichet Richard (BEFES Fondations & Structures), Mr. Huillard Xavier (President of VINCI), Mr. Llobet Lionel (COFEX-VINCI), Mr. Schmitt Pierre (SOLETANCHE- BACHY), Mr. Jérôme Stubler (President of VINCI Construction), Mr. Tadbir Eric (GINGER CEBTP), Mr. Henry Thonier, Mr. François Vahl and Mr. Jérôme Varillon (VINCI Construction Terrassement).