1st Edition

Geotechnics of Organic Soils and Peat

    282 Pages
    by CRC Press

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    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.


    Chapter 1: Introduction
    1.1 Soil Engineering
    1.2 Types and Formation of Soils
    1.2.1 Residual Soils
    1.2.2 Glacial Soils
    1.2.3 Alluvial Soils
    1.2.4 Lacustrine soils
    1.2.5 Marine Soils
    1.2.6 Aeolian Soils
    1.2.7 Colluvial Soils
    1.2.8 Organic Soils and Peat
    1.3 Engineering in the Peat Land
    1.4 About the book

    Chapter 2: Development of Peat Land and Types of Peat
    2.1 Introduction
    2.2 Definition of Peat and Organic Soils
    2.3 Classification on Fibre Content and Degree of Humification
    2.4 Development of Peat Land
    2.5 Site Investigation and Sampling of Peat
    2.5.1 Disturbed but representative sampling
    2.5.2 Undisturbed sampling
    2.5.3 In situ tests

    Chapter 3: Engineering Properties of Peat and Organic Soils
    3.1 Introduction
    3.2 Phases of Peat
    3.3 Botanical Origin and Fibre Content
    3.4 Fabric or Structure
    3.5 Soil Organic Colloids
    3.6 Humification of Peat
    3.7 Oxidation
    3.8 Organic Content
    3.9 Water content
    3.10 Atterberg limits
    3.11 Density and Specific Gravity
    3.12 Surface Charge Properties of Organic Soils and Peat
    3.12.1 Cation Exchange Capacity
    3.12.2 Zeta Potential of Organic Soils and Peat
    3.12.3 Resistivity of Organic Soils and Peat
    3.13 Correlations between Index parameters of Peat
    3.13.1 Water content-Organic content
    3.13.2 Water content-Liquid limit
    3.13.3 Organic content-Liquid limit
    3.13.4 Natural water content-Dry density
    3.13.5 Specific gravity-Organic content (Loss of Ignition)
    3.13.6 Bulk density-Loss of Ignition)
    3.13.7 Bulk density-Water content
    3.13.8 Compression index-Liquid limit
    3.14 Summary of Engineering Properties of Peat

    Chapter 4: Shear Strength of Natural Peat
    4.1 Introduction
    4.2 Laboratory Testing
    4.2.1 Drained Shear Strength Paramaters
    4.2.2 Undrained Shear Strength Parameters
    4.3 Vane Shear Strength
    4.4 Shear Strength Increase with Consolidation
    4.5 Effect of pH on Undrained Shear Strength
    4.6 Effect of Cyclic Loading
    4.7 Ko Behaviour
    4.8 Summary

    Chapter 5: Deformation Characteristics of Peat
    5.1 Introduction
    5.2 Compressibility Parameters of Peat
    5.2.1 Compression Index, cc and Void ratio
    5.2.2 Coefficient of Consolidation, cv
    5.2.3 Secondary Compression
    5.2.4 Tertiary Compression
    5.3 Hydraulic Conductivity
    5.3.1 Effect of pH on Permeability
    5.4 Final Settlement due to Surface Load
    5.5 Observational Methods

    Chapter 6: Soil Improvement and Construction Methods in Peat
    6.1 Introduction
    6.2 Excavation-Displacement and Replacement
    6.3 Surface Reinforcement, Preloading and Vertical Drain
    6.3.1 Surface Reinforcement
    6.3.2 Preloading
    6.3.3 Vacuum Preloading
    6.4 Deep Stabilisation
    6.4.1 Ras-Columns
    6.4.2 Cement Deep Mixing System (CDM)
    6.4.3 Jet Grouting System
    6.4.4 Vacuum Grouting Injection
    6.4.5 Dry Jet Mixing System (DJM)
    6.4.6 Dynamic Replacement Method
    6.4.7 Sand Drains and Sand/Stone Columns
    6.4.8 Vibrated Concrete Column
    6.5 Pile Support
    6.5.1 Types of Pile
    6.5.2 Pile Behaviour Geological behavior Inadequate Ground Investigation Construction behavior
    6.5.3 Piled Raft Foundation
    6.5.4 Pile Mat-JHS System
    6.5.5 AuGeo Pile System
    6.5.6 Friction/Floating Piles
    6.6 Chemical Stabilisation
    6.6.1 Chemical and Cementation Grouts
    6.6.2 Sodium Silicate System
    6.6.3 Silicate Chloride Amide System
    6.7 Decision on Choosing the Grout
    6.8 Lightweight Fill
    6.9 Other Methods of Construction
    6.9.1 Geocells
    6.9.2 Thermal Precompression
    6.9.3 Gap Method
    6.9.4 Reinforced Overlay
    6.10 Trial Embankments
    6.11 Chemical and Biological Changes
    6.12 Effect of Drainage
    6.13 Choice of Construction Methods

    Chapter 7: Recent Advances in Geotechnics of Organic Soils and Peat
    7.1 Introduction
    7.2 Electrokinetics
    7.2.1 Electroosmotics
    7.2.2 Electro-osmosis in Organic Soils and Peat
    7.3 Electrokinetic Cell
    7.4 Electrokinetic Stabilisation of Organic Soils and Peat
    7.5 Biocementing Stabilisation
    7.6 Biogrouting and its Challenges
    7.7 Electro-Biogrouting in Organic Soils and Peat
    7.8 Conventional Additives and/or Fibre Reinforcement in Organic Soils and Peat
    7.8.1 Ground granulated blast furnace slag (BFS)
    7.8.2 Pulverised-Fuel ash/Fly ash (FA)
    7.8.3 Silica Fume/Micro Silica (SFU)
    7.8.4 Polypropylene fibres (PPF)
    7.8.5 Steel fibres
    7.8.6 Cement and Fibres
    7.9 Peat Stabilisation by Reinforced Columns
    7.9.1 Cement-Sodium Silicate Stabilised Columns
    7.9.2 Cement and Silica Fume Stabilised Precast Columns
    7.9.3 Cement and Silica fume treated columns
    7.10 Geogrid Reinforced Vibro Compacted Stone Column
    7.11 New Deep Mixing Methods (DMM) for Stabilisation with New Chemical Binder

    Chapter 8: Environmental Geotechnics in Peat and Organic Soils
    8.1 Introduction
    8.2 Peat Hydrology
    8.3 Physico-Chemical Properties of Peat
    8.4 Physico-Chemical Properties of Peat Pore Fluid
    8.5 Common Ground between Soil Scientists and Geotechnical Engineers
    8.6 Chemical and Biological Changes
    8.7 Effect of Drainage
    8.8 Effect of Peat Media on Stabilisation Procedure
    8.8.1 Effect of CO2 on treated peat
    8.8.2 Effect of N on treated peat
    8.8.3 Effect of pH on treated peat
    8.9 Continuing Research in Peat Land Development


    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.