Environmental Geomechanics E-Book

• Herausgeber: John Wiley & Sons
• Kategorie: Wissenschaft und neue Technologien
• Sprache: Englisch

Seitenzahl: 696

Veröffentlichungsjahr: 2013

Beschreibung

This book covers a range of topics that are of increasing importance in engineering practice: natural hazards, pollution, and environmental protection through good practice. The first half of the book deals with natural risk factors, of both natural and human origin, that should be considered: subsidence, accidental infiltration, soil instability, rockslides and mudslides, debris flow, and degradation of buildings and monuments due to pollution and climactic effects, for example. These problems are highlighted and it is shown that a combination of sophisticated numerical techniques and extensive experimental investigations are necessary in order to effectively tackle these problems. The second half of the book is devoted to the use of polluted sites and associated problems, a topic of growing significance given the increasing reclamation of land from abandoned industrial sites for urban development over the last 20 years. Different types of oil pollution and decontamination methods are described, followed by a discussion of waste management and detailed coverage of confinement liners used in surface waste disposal.

Leseprobe

Table of Contents

Introduction

Chapter 1: Debris Flows

1.1. Introduction

1.2. Typology of torrential flows

1.3. Initiation, motion and effects of debris flow

1.4. Modeling debris flows

1.5. Bibliography

Chapter 2: Snow Avalanches

2.1. Introduction

2.2. Modeling avalanches

2.3. Bibliography

Chapter 3: Instability of Soil Masses

3.1. Introduction

3.2. Slowly moving slopes

3.3. Limit state analysis

3.4. Case of non-saturated masses

3.5. Conclusion and prospects

3.6. Bibliography

Chapter 4: Instability of Rock Masses

4.1. Introduction

4.2. Cliff stability and toppling

4.3. Contact-impact

4.4. Flight trajectory

4.5. Sliding and rolling

4.6. Impact on an embankment (safety embankment)

4.7. Capacity of the protective structures

4.8. Conclusion

4.9. Bibliography

Chapter 5: Subsidence Phenomena

5.1. Subsidence caused by water withdrawal

5.2. Artificially-induced land uplift

5.3. Conclusions

5.4. Bibliography

Chapter 6: Soil Collapse due to Water Infiltration

6.1. Introduction

6.2. The loess in Northern France

6.3. Conclusion

6.4. Bibliography

Chapter 7: Subsidence Induced by Fossil Fuel Extraction

7.1. Introduction

7.2. Subsidence due to coal extraction

7.3. Recap of the basic Barcelona model

7.4. Subsidence due to oil exploitation

7.5. Subsidence due to the exploitation of gas reservoirs

7.6. Acknowledgements

7.7. Bibliography

Chapter 8: Deterioration of Stone in Monuments

8.1. Introduction

8.2. Intrinsic degradation factors

8.3. Extrinsic degradation factors

8.4. Acknowledgements

8.5. Bibliography

Chapter 9: The Physics of Water Transfer in Stone

9.1. General concepts and terminology

9.2. Water in stones: capillarity

9.3. Modeling water transfer in stone

9.4. Bibliography

Chapter 10: Experimental Techniques for Characterizing Alterations

10.1. Laboratory and in situ testing

10.2. Hydric and thermal transfers: specific techniques

10.3. Bibliography

Chapter 11: Case Studies

11.1. Notre-Dame-la-Grande Church in Poitiers, in situ study

11.2. Research on earthen plaster stabilized with bitumen and polychrome decoration: Navrongo cathedral, North Ghana

11.3. Bibliography

Chapter 12: The Nature and Survey of Soil Pollution

12.1. Introduction

12.2. The nature of soil pollution

12.3. The survey of contaminated sites

12.4. Conclusions

12.5. Bibliography

Chapter 13: Retention and Transfer of Soluble Chemical Pollutants: Mechanisms and Numerical Modeling

13.1. Introduction

13.2. Ideal pollutant transport in an ideal continuous medium

13.3. Pollutant retention phenomena

13.4. Balance equations

13.5. Numerical modeling of transport by advection

13.6. Finite elements modeling of the problem with advection and diffusion

13.7. Examples and applications

13.8. Conclusions

13.9. Acknowledgments

13.10. Bibliography

13.11. Notations table

Chapter 14: Retention and Transfer of Pollution by Hydrocarbons: Mechanisms and Numerical Modeling

14.1. Introduction

14.2. Mechanisms

14.3. Numerical modeling

14.4. Conclusion

14.5. Bibliography

Chapter 15: Methods of Soil Environmental Remediation

15.1. Introduction

15.2. Pollution control techniques

15.3. Active containment in situ

15.4. Passive treatment in situ

15.5. Active treatment in situ

15.6. Conclusions

15.7. Bibliography

Chapter 16: Liners for Waste Containment Facilities

16.1. Introduction

16.2. Types of lining systems and definition of basic components

16.3. Mass balance of the contaminants

16.4. Functions, performance and modeling

16.5. Environmental impact evaluation (risk analysis)

16.6. Bottom barriers

16.7. Equivalence of liner systems

16.8. Composite liners

16.9. Conclusions

16.10. Bilbliography

List of Authors

Index

First published 2010 in Great Britain and the United States by ISTE Ltd and John Wiley & Sons, Inc. Adapted and updated from two volumes Géomécanique environnementale published 2001 and 2005 in France by Hermes Science/Lavoisier © LAVOISIER 2001, 2005

Apart from any fair dealing for the purposes of research or private study, or criticism or review, as permitted under the Copyright, Designs and Patents Act 1988, this publication may only be reproduced, stored or transmitted, in any form or by any means, with the prior permission in writing of the publishers, or in the case of reprographic reproduction in accordance with the terms and licenses issued by the CLA. Enquiries concerning reproduction outside these terms should be sent to the publishers at the undermentioned address:

ISTE Ltd27-37 St George’s RoadLondon SW19 4EUUKwww.wiley.comJohn Wiley & Sons, Inc.111 River StreetHoboken, NJ 07030USAwww.iste.co.uk

© ISTE Ltd 2010

The rights of Bernhard Schrefler and Pierre Delage to be identified as the authors of this work have been asserted by them in accordance with the Copyright, Designs and Patents Act 1988.

Library of Congress Cataloging-in-Publication Data

Schrefler, B. A.

Environmental geomechanics / edited by Bernhard Schrefler, Pierre Delage.

p. cm.

Includes bibliographical references and index.

ISBN 978-1-84821-166-7

1. Environmental geotechnology. 2. Soil pollution. I. Delage, Pierre. II. Title.

TD171.9.S37 2010

628.5’5--dc22

2010019877

British Library Cataloguing-in-Publication Data

A CIP record for this book is available from the British Library

ISBN 978-1-84821-166-7

Introduction

This book is devoted to environmental geomechanics, addressing the natural risks to the conservation of built cultural heritage, and the risks of soil pollution and waste respectively. Environmental geomechanics is a rapidly expanding field dealing mostly with the following surface structures such as: earth dams; embankments; the built environment; underground structures for storage and other civil engineering applications; with natural sites such as slopes and cliffs; and more generally with the geosphere involving reservoir engineering, mining, quarries and man-made deposits.

The chapters contained in this book address many of these problems. The book is certainly not exhaustive but the problems dealt with are characterized from a geomechanics point of view by the fact that coupling effects in the multiphase deforming geomaterials are taken into account; couplings due to heat, mass and pollutant transfer and to climatic variations and human action. The geomaterials taken into consideration are soil and rock, which may also be used as building materials. The fluids in the pores of these geomaterials are mainly water in a liquid or gaseous form, dry air but also hydrocarbons such as oil and natural gas. The solid phase may also undergo chemical transformation as in the case of the degradation of natural building stones. Phase changes are important and are linked to precipitation, condensation, evaporation, radiation, pollution, etc.

The natural risks mentioned in the first part of the book are linked with gravity effects on inclined masses, and include the instability of snow masses, soils, rocks and material transported in rivers. Surface subsidence and collapse of horizontal soil masses linked to human activity such as withdrawal of liquid or gaseous hydrocarbons from underground reservoirs or accidental infiltrations are then considered. The chapters devoted to the conservation of cultural heritage deal with the degradation of building stones and earthen plaster due to climate and pollution. This problem also involves several interactions with phase change including fluid transfer and important chemical effects. The solution of these complex problems requires extensive use of numerical methods and a great diversity of experimental techniques. Two case studies show how the combination of the presented tools enables the preservation of European and African churches.

The second half of the book discusses environmental problems such as polluted soils and waste, the importance of which has grown increasingly over recent years in industrialized countries and are now becoming just as important in developing countries.

The problems posed by polluted soils have been recognized for more than two decades due to the popularity of redevelopment of sites and industrial land, often in semi-urban zones in developing towns. We have thus realized how little attention was paid in the industrial period to the protection of soils, a feeling probably reinforced by the invisible factor of soil pollution. In fact, soil pollution receives less attention from society (media, associations, etc.) than that given to air and water pollution. We are however observing that the significant mobilization of interest in recent years has recently been transcribed by a complete set of detailed and accessible methodological guides being put into practice, from the methodology of recognizing polluted sites to their eventual pollution control in the case of established risk.

Furthermore, waste management was for a long time carried out without considering on the one hand how to store the waste in perennial conditions and thus assuring the long-term protection of the environment, and on the other hand how to limit the production of waste through incentive measures at the source and by waste sorting.

For these two problems the phenomena of retention and transport of various pollutants (soluble, metallic and hydrocarbon) in geomaterials (natural soils or compacted confinement barriers in storage centers) rest on the various physical chemical laws that are described by the equations. A good knowledge of the phenomena of the retention and transfer of pollutants is essential for the understanding of past movements of pollutants or those still to come, as well as for the optimization of their pollution control. Numerical modeling of these transfers is now quite well known and we will see in this book how it is treated for each of the pollutants considered. These models are probably most characterized by the many thermo-hydro-chemical-mechanical couplings which are largely non-linear, which recent progress in numerical modeling has enabled us to solve in a satisfactory way.

Chapter 1

Debris Flows1

1.1. Introduction

Debris flows are a major natural hazard, claiming thousands of lives and millions of dollars in property loss each year in almost all mountainous areas on the Earth. After a catastrophic eruption of Mount St. Helen in the United States in May 1980, water from melting snow, torrential rains from the eruption cloud, and water displaced from Spirit Lake mixed with deposited ash and debris produced very large debris flows and caused extensive damage and loss of life [SCO 88]. During the 1985 eruption of Nevado del Ruiz in Colombia, more than 20,000 people perished when a large debris flow triggered by the rapid melting of snow and ice at the volcano summit swept through the town of Armero [VOI 90]. In 1991, the eruption of Pinatubo volcano in the Philippines dispersed more than 5 km3 of volcanic ash into surrounding valleys. Much of that sediment has subsequently been mobilized as debris flows by typhoon rains and has devastated more than 300 km2 of agricultural land. Even in European countries, recent events of torrential floods may have very destructive effects (Sarno and Quindici in southern Italy in May 1998, where approximately 200 people were killed).

The catastrophic character of these floods in mountainous watersheds is a consequence of significant transport of materials associated with water flows. Two limiting flow regimes can be distinguished. Bed load and suspension refer to dilute transport of sediments within water. This means that water is the main agent in the flow dynamics and that the particle concentration does not exceed a few percent. Such flows are typically two-phase flows. In contrast, debris flows are mass movements of concentrated slurries of water, fine solids, rocks and boulders. As a first approximation, debris flows can be treated as one-phase flows, and their flow properties can be studied using classical rheological methods. The study of debris flows is a very exciting albeit immature science, made up of disparate elements borrowed from geomorphology, geology, hydrology, soil mechanics and fluid mechanics. The purpose of this chapter is to provide an introduction to the physical aspects of debris flows, with specific attention directed to their rheological features. Despite attempts to provide a coherent view on the topic, coverage is incomplete and the reader is referred to a series of papers and books. A few books are particularly commendable [BRU 84, COU 97, JOH 84, ZIM 97]. Some review papers provide interesting overviews, introducing newcomers to the field to the main concepts [ANC 07, CHE 87, COU 96b, IVE 97, IVE 05, RIC 99, TAK 81].

1.2. Typology of torrential flows

1.2.1. Watershed as a complex physical system

The notion of a torrent refers to a steep stream, typically in a mountainous context [MON 97, WOH 00]. According to a few authors, a stream can be referred to as a torrent as soon as its mean slope exceeds 6% [BER 27]. For bed slopes ranging from 1 to 6%, it is called a torrential river. For bed slopes lower than 1%, it can be merely called a river. In addition to the slope, the sediment supply is generally considered as another key ingredient in torrential watersheds. Depending on the nature of the soil and relief, slopes can provide a large quantity of poorly sorted solid materials to torrents. Supplied materials have sizes ranging typically from 1 μm to 10 m. The situation is very different from the one encountered for streams on a plain, where bed material is much finer and ordered (typically 1 μm to 10cm) since it generally results from transport that occurred during previous floods. Finally, one of the chief ingredients of torrential watersheds is water. Owing to the small dimensions of torrential watersheds (typically from 0.1 to 100 km2) and the steep slopes, floods are sudden, short and violent. The flood regime differs significantly from plain floods, which are characterized by slower kinetics and smoother variations with time. Figure 1.1 shows a typical watershed. The upper part is generally degraded and submitted to erosion to a more or less large extent. It supplies water and sediment to the floods. Below this basin, the torrent enters a gorge, sometimes with very abrupt flanks depending on the nature of the soil. Then the torrent discharges onto the alluvial fan. The slope transition between the gorge and the alluvial provides interesting information on bed equilibrium. Generally, a watershed with an abundant supply of sediment and intense bed load transport in the past is characterized by a smooth transition from channel to fan.

For plain rivers, sediment transport results from the action of water: water entrains materials either by pushing them along the bed (bed load transport) or by keeping them in suspension as a result of turbulence (suspension). In a torrential context, as

Figure 1.1.A typical watershed: the Brandy torrent (Savoie, France)

soon as the bed inclination is sufficiently high, gravity has a more pronounced role on sediment transport. Therefore, on the one hand, bed load transport is more intense, and on the other hand, a new mode of transport arises: debris flow (see Figure 1.2). We can define them as follows:

– Debris flows are highly concentrated mixtures of sediments and water, flowing as a single-phase system. Debris flows look like mudslides and landslides except that their velocity and the distances they travel are much larger. It is worth noting that in the literature there are many terms used to refer to slides and/or debris flows, which is a source of confusion.

– Bed load transport involves transportation of sediment by water. Coarse particles (sand, gravel and boulders) roll and slide in a thin layer near the bed (called the bed layer). Generally, fine particles (silts and clays) are brought into suspension as a result of water turbulence. The system is typically made up of two distinct phases: liquid phase (i.e. water) and dispersed (solid) phase.

1.2.2. Types of transport

In the laboratory, it is possible to simulate torrential phenomena using an inclined channel with a mobile bed made up of sand and gravel. and show two very different situations that can be observed when the channel slope is increased by only a few percent. corresponds to a slope of 17%. At