Geotechnics of organic soils and peat

Title:

Personal Author:

Huat, Bujang B. K.

Publication Information:

CRC Press, 2013

ISBN:

9780415659413

Peat and organic soils commonly occur as extremely soft, wet, unconsolidated surficial deposits that are an integral part of wetland systems. These types of soils can give rise to geotechnical problems in the area of sampling, settlement, stability, in situ testing, stabilisation and construction. There is therefore a tendency to either avoid building on these soils, or, when this is not possible, to simply remove or replace soils, which in some instances can lead to possibly uneconomical design and construction alternatives. However, in many countries of the world, these soils cover a substantial land area and pressure on land use is resulting in ever more frequent utilisation of such marginal grounds.

For the successful design, construction and performance of structures on such marginal soils, it is crucial to predict geotechnical behaviour in terms of settlement, shear strength and stability, with respect to time. This means expanding our knowledge base and calls for a reliable characterisation of their geotechnical properties and mechanical behaviour and subsequently, the devising of suitable design parameters and construction techniques for dealing with these materials.

A sound scientific understanding of the nature and functions of peat and organic soils is critical to their correct and safe use, and this book contributes by offering students, researchers, engineers and academics involved with these types of soils a comprehensive overview. This book will be useful not only to those in the field of geotechnical engineering, but also to soil scientists and agriculturalists, who are involved in the development of peatlands.

Author Notes

Bujang B.K. Huat graduated from the Polytechnic of Central London, UK in 1983, and obtained his MSc and PhD at the Imperial College London and the Victoria University Manchester, UK in 1986 and 1991 respectively. He has spent his professional career as a Professor in Geotechnical Engineering, at the Department of Civil Engineering, Universiti Putra Malaysia, one of Malaysia's five research universities. Currently he serves as the Dean of School of Graduate Studies of the same university. His special area of interest is in the field of geotechnical and geological engineering, especially peat, and slope engineering; he has authored and co-authored 18 books, edited ten conference proceedings, and published more than 100 journal and conference proceedings papers in the field of soil mechanics and foundation engineering.

Arun Prasad is Associate Professor of Geotechnical Engineering at the Indian Institute of Technology (Banaras Hindu University), India. He graduated with a BSc in Civil Engineering in 1986 from Utkal University, India; he obtained his MSc and PhD from Sambalpur University and Devi Ahilya University, India in 1989 and 2000 respectively. He worked as Post-Doctoral Researcher at Universiti Putra Malaysia during 2009-10. His special area of research is the soil stabilization of soft and contaminated soils. He has co-authored three books and co-edited a book in the field of Geotechnical Engineering, and has published more than 60 papers in journals and conference proceedings.

Dr. Afshin Asadi received his BSc in Civil Engineering from IAU, his MSc in Civil Engineering-Environmental Engineering from the Iran University of Science and Technology, and his PhD in Geotechnical Engineering from University Putra Malaysia in 2010. He received an Australia Endeavour Research Fellowship Award in 2011 and completed his postdoctoral studies at the University of Wollongong in 2012. His research areas are mostly ground improvement, electrokinetics, and environmental geotechnics. He is a member of the Environmental Geotechnics editorial board published by ICE Publishing, UK. Presently, he is a Research Fellow at the Housing Research Centre (HRC), University Putra Malaysia.

Sina Kazemian is Assistant Professor at the Civil Engineering department of Payame Noor University (PNUM), I.R. of Iran He obtained his PhD (with distinction) in Geotechnical and Geological Engineering from Universiti Putra Malaysia (UPM) and achieved recognition of excellence during his PhD viva; his name was inscribed in the "Hall of Fame'' at UPM. He has worked as a lecturer/researcher at Azad University of Bojnourd, Iran and also has more than 10 years of working experience in the industry as Senior Geotechnical Engineer at Sepehr Andishan Sanabad (SAS) Co., Iran and Structure Civil Geotechnics (SCG) Co., Malaysia. Currently, he is also the Principal Geotechnical Engineer and technical associate of Kavosh Pay Co. in Iran. To date he has published more than 100
papers in reputed journals and conference proceedings.

Foreword	p. ix
About the authors	p. xi
1 Introduction	p. 1
1.1 Soil engineerin	p. 1
1.2 Types and formation of soils	p. 1
1.2.1 Residual soils	p. 1
1.2.2 Glacial soils	p. 3
1.2.3 Alluvial soils	p. 4
1.2.4 Lacustrine soils	p. 5
1.2.5 Marine soils	p. 5
1.2.6 Aeolian soils	p. 6
1.2.7 Colluvial soils	p. 7
1.2.8 Organic soils and peat	p. 7
1.3 Engineering in peat land	p. 10
2 Development of peat land and types of peat	p. 13
2.1 Introduction	p. 13
2.2 Definition of peat and organic soils	p. 16
2.3 Classification based on fibre content and degree of humification	p. 19
2.4 Development of peat land	p. 23
2.5 Site investigations and sampling of peat	p. 31
2.5.1 Disturbed but representative sampling	p. 33
2.5.2 Undisturbed sampling	p. 34
2.5.3 In situ tests	p. 38
3 Engineering properties of peat and organic soils	p. 43
3.1 Introduction	p. 43
3.2 Phases of peat	p. 43
3.3 Botanical origin and fibre content	p. 44
3.4 Fabric or structure	p. 45
3.5 Soil organic colloids	p. 47
3.6 Humification of peat	p. 48
3.7 Oxidation	p. 50
3.8 Organic content	p. 52
3.9 Water content	p. 53
3.10 Atterberg limits	p. 54
3.11 Density and specific gravity	p. 55
3.12 Surface charge properties of organic soils and peat	p. 58
3.12.1 Cation exchange capacity	p. 58
3.12.2 Zeta potential of organic soils and peat	p. 62
3.12.3 Resistivity of organic soils and peat	p. 69
3.13 Correlations between index parameters of pear	p. 70
3.13.1 Water content vs. organic content	p. 71
3.13.2 Water content vs. liquid limit	p. 72
3.13.3 Organic content vs. liquid limit	p. 72
3.13.4 Natural water content vs. dry density	p. 72
3.13.5 Specific gravity vs. organic content (loss of ignition)	p. 73
3.13.6 Bulk density vs. loss of ignition	p. 75
3.13.7 Bulk density vs. water content	p. 77
3.13.8 Compression index vs. liquid limit	p. 77
3.14 Summary of engineering properties of peat	p. 77
4 Shear strength of natural peat	p. 81
4.1 Introduction	p. 81
4.2 Laboratory testing	p. 83
4.2.1 Drained shear strength parameters	p. 86
4.2.2 Undrained shear strength parameters	p. 86
4.3 Vane shear strength	p. 88
4.4 Shear strength increase with consolidation	p. 91
4.5 Effect of pH on undrained shear strength	p. 92
4.6 Effect of cyclic loading	p. 93
4.7 K o Behaviour	p. 94
4.8 Summary	p. 95
5 Deformation characteristics of peat	p. 97
5.1 Introduction	p. 97
5.2 Compressibility parameters of peat	p. 99
5.2.1 Compression index, c c and void ratio	p. 103
5.2.2 Coefficient of consolidation, c v	p. 106
5.2.3 Secondary compression	p. 111
5.2.4 Tertiary compression	p. 113
5.3 Hydraulic conductivity	p. 115
5.3.1 Effect of pH on permeability	p. 117
5.4 Final settlement due to surface load	p. 117
5.5 Observational methods	p. 118
6 Soil improvement and construction methods in peat	p. 121
6.1 Introduction	p. 121
6.2 Excavation - displacement and replacement	p. 125
6.3 Surface reinforcement, preloading and vertical drain	p. 126
6.3.1 Surface reinforcement	p. 126
6.3.2 Preloading	p. 128
6.3.3 Vacuum preloading	p. 130
6.4 Deep stabilization	p. 135
6.4.1 Ras-columns	p. 139
6.4.2 Cement deep mixing system (CDM)	p. 140
6.4.3 Jet grouting systems	p. 141
6.4.4 Vacuum grouting injection	p. 141
6.4.5 Dry jet mixing system (DJM)	p. 142
6.4.6 Dynamic replacement method	p. 142
6.4.7 Sand drains and sand/stone columns	p. 143
6.4.8 Vibrated concrete column	p. 143
6.5 Pile suport	p. 143
6.5.1 Types of pile	p. 144
6.5.2 Pile behaviour	p. 145
6.5.2.1 Geological behaviour	p. 145
6.5.2.2 Inadequate ground investigation	p. 146
6.5.2.3 Construction behaviour	p. 147
6.5.3 Piled raft foundation	p. 148
6.5.4 Pile mat-JHS system	p. 151
6.5.5 AuGeo pile system	p. 152
6.5.6 Friction/floating piles	p. 153
6.6 Chemical stabilization	p. 156
6.6.1 Chemical and cementation grouts	p. 156
6.6.2 Sodium silicate system	p. 156
6.6.3 Silicate chloride amide system	p. 157
6.7 Choosing the grout	p. 157
6.8 Lightweight fill	p. 157
6.9 Other methods of construction	p. 162
6.9.1 Geocells	p. 162
6.9.2 Thermal precompression	p. 162
6.9.3 Gap method	p. 162
6.9.4 Reinforced overlay	p. 162
6.10 Trial embankments	p. 163
6.11 Chemical and biological changes	p. 165
6.12 Effect of drainage	p. 166
6.13 Choice of construction methods	p. 168
7 Recent advances in the geotechnics of organic soils and peat	p. 171
7.1 Introduction	p. 171
7.2 Electrokinetics	p. 171
7.2.1 Electroosmotics	p. 173
7.2.2 Electroosmosis in organic soils and peat	p. 177
7.3 Electrokinetic cell	p. 180
7.4 Electrokinetic stabilization of organic soils and peat	p. 182
7.5 Biocementing stabilization	p. 183
7.6 Biogrouting and its challenges	p. 184
7.7 Electro-biogrouting in organic soils and peat	p. 185
7.8 Conventional additives and/or fibre reinforcement in organic soils and peat	p. 186
7.8.1 Ground granulated blast furnace slag (BFS)	p. 186
7.8.2 Pulverized fuel ash/fly ash (FA)	p. 187
7.8.3 Silica fume/micro silica (SFU)	p. 188
7.8.4 Polypropylene fibres (PPF)	p. 192
7.8.5 Steel fibres	p. 199
7.8.6 Cement and fibres	p. 200
7.9 Peat stabilization by reinforced columns	p. 201
7.9.1 Cement-sodium silicate stabilized columns	p. 204
7.9.2 Cement and silica fume stabilized precast columns	p. 207
7.10 Geogrid reinforced vibrocompacted stone column	p. 209
7.11 New deep mixing methods (DMM) for stabilization with new chemical binders	p. 212
8 Environmental geotechnics in peat and organic soils	p. 219
8.1 Introduction	p. 219
8.2 Peat hydrology	p. 219
8.3 Physico-chemical properties of peat	p. 222
8.4 Physico-chemical properties of peat pore fluid	p. 226
8.5 Common ground between soil scientists and geotechnical engineers	p. 228
8.6 Chemical and biological changes	p. 233
8.7 Effect of peat media on stabilization procedure	p. 233
8.7.1 Effect of CO 2 on treated peat	p. 233
8.7.2 Effect of N on treated peat	p. 235
8.7.3 Effect of pH on treated peat	p. 237
8.8 Continuing research in peat land development	p. 237
References	p. 239
Subject index	p. 265

On Order

Summary

Summary

Author Notes

Table of Contents