Advanced Unsaturated Soil Mechanics and Engineering

710 Pages·2007·7.78 MB·English

Advanced Unsaturated Soil
Mechanics and Engineering
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Advanced Unsaturated
Soil Mechanics and
Engineering
Charles W.W. Ng and
Bruce Menzies
Firstpublished2007
byTaylor&Francis
2ParkSquare,MiltonPark,Abingdon,OxonOX144RN
SimultaneouslypublishedintheUSAandCanada
byTaylor&Francis
270MadisonAve,NewYork,NY10016,USA
This edition published in the Taylor & Francis e-Library, 2007.
“To purchase your own copy of this or any of Taylor & Francis or Routledge’s
collection of thousands of eBooks please go to www.eBookstore.tandf.co.uk.”
Taylor&FrancisisanimprintoftheTaylor&FrancisGroup,aninforma
business
©2007CharlesW.W.NgandBruceMenzies
Allrightsreserved.Nopartofthisbookmaybereprintedor
reproducedorutilisedinanyformorbyanyelectronic,mechanical,or
othermeans,nowknownorhereafterinvented,includingphotocopying
andrecording,orinanyinformationstorageorretrievalsystem,without
permissioninwritingfromthepublishers.
Thepublishermakesnorepresentation,expressorimplied,withregard
totheaccuracyoftheinformationcontainedinthisbookandcannot
acceptanylegalresponsibilityorliabilityforanyeffortsor
omissionsthatmaybemade.
BritishLibraryCataloguinginPublicationData
AcataloguerecordforthisbookisavailablefromtheBritishLibrary
LibraryofCongressCataloginginPublicationData
Ng,C.W.W.
Unsaturatedsoilmechanicsandengineering/CharlesW.W.Ngand
BruceMenzies.
p.cm.
Includesbibliographicalreferencesandindex.
ISBN978-0-415-43679-3(hardback:alk.paper)--
ISBN978-0-203-93972-7(ebook)1.Soilmechanics.2.Swellingsoils.
3.Zoneofaeration.4.Soilmoisture.I.Menzies,BruceKeith.II.Title.
TA710.N4752007
624.1(cid:2)5136--dc22
2007008742
ISBN 0-203-93972-7 Master e-book ISBN
ISBN978–0–415–43679–3Hardback
ISBN978–0–203–93972–7eBook
Dedicated To Professor Delwyn G. Fredlund, Unsaturated Soil
Mechanics Pioneer
Delwyn G. Fredlund O.C., Ph.D., F.E.I.C., P.Eng.
Senior Geotechnical Engineering Specialist, Golder Associates, 2005–
Professor Emeritus, University of Saskatchewan, from 2000
K.P. Chao Chair, Zhejiang University, 2007–2009
AdjunctProfessor,HongKongUniversityofScienceandTechnology,2001–
Adjunct Professor, University of Alberta, 2002–
Honorary Professor, University of British Columbia, 2002–
Research Professor, Arizona State University, 2004–
If you learn to think the way unsaturated soil behaves, then you will make
wise engineering decisions.
(Del Fredlund’s advice to students)
Cover Frontispiece
GDS pneumatic
controllers, σr, ua
GDS digital
transducer interface
GDS hydraulic
pressure/volume
controllers, σa, uw
HKUST total
volume change
measuring system
Bishop & Wesley
triaxial cell
(a)
Diffused air
volume indicator
(b)
q
Differential pressure transducer
q = μ(s) + M(s)p
(critical state) Reference tube
q = ηy(p + μ(s)/M(s))
(fs yield surface) Inner chamber
M(s)
p = p0(s)
μ(s) ηy (fc yield surface)
Ðμ(s)/M(s)) p
(d) (c)
Imagesthatrepresentthecontentofthisbook:(a)Retrogressivefailuresinanunsaturated
expansivesoilslope(Ngetal.,2003);(b)HKUST–GDScomputercontrolledtriaxialstress-
path apparatus equipped with double wall total volume measuring system; (c) HKUST
measurement of total volume change (double wall system) using a differential pressure
transducer(Ngetal.,2002);(d)Yieldsurfaceinq−pspaceatconstantsuction(Chiuand
Ng,2003).
Book overview
Civil engineers build on or in the earth’s surface. Most of the earth’s land
surface comprises notoriously hazardous geomaterials called ‘unsaturated
soils’. These soils are a hazard to earth structures and earth-supported
structures because on wetting, by rain or other means, they can expand or
collapse with serious consequences for cost and safety. This book puts the
mechanics and engineering of unsaturated soils into a logical framework
forcivilengineeringanalysisanddesign.Italsoexplainsthelaboratoryand
fieldtestingandresearchthatarethelogicalbasisofthismodernapproach
to safe construction in these hazardous geomaterials.
This state-of-the-art book is written in four parts as follows:
1. Physical and flow characteristics of unsaturated soils;
2. Collapse, swelling, shear strength and stiffness of unsaturated soils;
3. State-dependent elasto-plastic modelling of unsaturated soils;
4. Field trials and numerical studies in slope engineering of unsatu-
rated soils.
This book is unique because:
•
itillustratestheimportanceofstate-dependentsoil–watercharacteristic
curves;
•
highlights modern soil testing of unsaturated soil behaviour, including
accuratemeasurementoftotalvolumechangesandthemeasurementof
anisotropic soil stiffness at very small strains;
•
introduces an advanced state-dependent elasto-plastic constitutive
model for both saturated and unsaturated soil;
•
demonstrates the power of numerical analysis which is at the heart of
modern soil mechanics;
•
studies and simulates the behaviour of loose fills from unsaturated to
saturated states, explains the difference between strain-softening and
static liquefaction, and describes real applications in unsaturated soil
slope engineering;
•
includespurpose-designedfieldtrialstocapturetheeffectsoftwoinde-
pendent stress variables, and reports comprehensive measurements of
soilsuction,watercontents,stresschangesandgrounddeformationsin
bare slopes;
•
introduces a new conjunctive surface and subsurface transient flow
model for realistically analysing rainfall infiltration in unsaturated soil
slopes, and illustrates the importance of the flow model in slope engi-
neering.

Contents
Authors’ biographical details xiii
Preface xiv
Acknowledgements xvii
PART 1
Physical and flow characteristics of
unsaturated soils 1
Part 1 Frontispiece 2
Chapter synopses 3
1 Basic physics, phases and stress state variables 5
Sources 5
Introduction (Fredlund, 1996) 5
Four-phase materials (Fredlund and Rahardjo, 1993) 20
Cavitation (Young, 1989; Marinho, 1995;
Marinho and de Sousa Pinto, 1997) 24
2 Measurement and control of suction: methods and
applications 31
Sources 31
Theory of soil suction (Fredlund and Rahardjo, 1993) 32
The capillary model 32
Suction control and measurement methods
(Ng and Chen, 2005, 2006; Ng et al., 2007a) 36
Suction measuring devices (Fredlund and Rahardjo, 1993;
Ridley and Wray, 1995; Feng and Fredlund, 2003) 63
Case study: comparisons of in situ suction
measurements (Harrison and Blight, 2000) 87