Your guide to the design and construction of foundations on expansive soils Foundation Engineering for Expansive Soils fills a significant gap in the current literature by presenting coverage of the design and construction of foundations for expansive soils. Written by an expert author team with nearly 70 years of combined industry experience, this important new work is the only modern guide to the subject, describing proven methods for identifying and analyzing expansive soils and developing foundation designs appropriate for specific locations.
Your guide to the design and construction of foundations on expansive soils
Foundation Engineering for Expansive Soils fills a significant gap in the current literature by presenting coverage of the design and construction of foundations for expansive soils. Written by an expert author team with nearly 70 years of combined industry experience, this important new work is the only modern guide to the subject, describing proven methods for identifying and analyzing expansive soils and developing foundation designs appropriate for specific locations.
Expansive soils are found worldwide and are the leading cause of damage to structural roads. The primary problem that arises with regard to expansive soils is that deformations are significantly greater than in non-expansive soils and the size and direction of the deformations are difficult to predict. Now, Foundation Engineering for Expansive Soils gives engineers and contractors coverage of this subject from a design perspective, rather than a theoretical one. Plus, they'll have access to case studies covering the design and construction of foundations on expansive salts from both commercial and residential projects.
•Provides a succinct introduction to the basics of expansive soils and their threats
•Includes information on both shallow and deep foundation design
•Profiles soil remediation techniques, backed-up with numerous case studies
•Covers the most commonly used laboratory tests and site investigation techniques used for establishing the physical properties of expansive soils
If you're a practicing civil engineer, geotechnical engineer or contractor, geologist, structural engineer, or an upper-level undergraduate or graduate student of one of these disciplines, Foundation Engineering for Expansive Soils is a must-have addition to your library of resources.
Table of Contents
Preface
List of Symbols
List of Abbreviations
1. INTRODUCTION
1.1 Purpose
1.2 Organization
1.3 Terminology
References
2. NATURE OF EXPANSIVE SOILS
2.1 Microscale Aspects of Expansive Soil Behavior
2.1.1 The Clay Particle
2.1.1.1 Mineral Composition
2.1.1.2. Interlayer Composition
2.1.1.3. Isomorphous Subtitution and Surface Charges
2.1.2 Adsorbed Cations and Cation Hydration
2.1.3 The Clay Micelle
2.1.4 Crystalline and Osmotic Expansion
2.1.5 Effect of Mineralogy on Plasticity of Soil
2.1.6 Effect of Mineralogy on Expansion Potential
2.1.7 Effect of Type of Cation on Expansion Potential
2.2 Macroscale Aspects of Expansive Soil Behavior 24
2.2.1 Development of Natural Soil Deposits 24
2.2.2 Effect of Plasticity on Expansion Potential 26
2.2.3 Effect of Soil Structure, Water Content, and Density on Expansion Potential 27
2.3 Identification of Expansive Soils 30
2.3.1 Methods Based on Physical Properties 30
2.3.1.1. Methods Based on Plascicity
2.3.1.2 Free Swell Test
2.3.1.3. Potentional Volume Change ( PVC)
2.3.1.4. Expansion Index ( EI ) Test
2.3.1.5. Coefficient of Linear Extensibility ( COLE )
2.3.1.6. Standard Absorption Moisture Content ( SAMC )
2.3.2 Mineralogical Methods
2.3.3 Chemical Methods
2.3.3.1. Cation Exchange Capacity ( CEC )
2.3.3.2. Specific Surface Area ( SSA )
2.3.3.3. Total Potassium ( TP)
2.3.4 Comments on Identification Methods
2.4 Characteristics of Expansive Soil Profiles
2.4.1 Geographic Distribution of Expansive Soils
2.4.2 Expansive Soil Profiles
2.4.2.1. Welkom,South Africa
2.4.2.2 Maryland, Australia
2.4.2.3. Regina,Saskatchewan, Canada
2.4.2.4. Front Range Area of Colorado USA
2.4.2.5 San Antonio,Texas USA
References
3. SITE INVESTIGATION
3.1 Program of Exploration
3.1.1 Reconnaissance Investigation
3.1.2 Preliminary Investigation
3.1.3 Design-Level Investigation
3.1.3.1 Distribution of Borings
3.1.3.2.Depth of Exploration
3.1.3.3.Sampling Frequency and Depth
3.2 Forensic Investigation
References
4. SOIL SUCTION
4.1 Soil Suction Components
4.1.1 Matric Suction
4.1.2 Osmotic Suction
4.1.3 Total Suction
4.2 Soil Water Characteristic Curve
4.2.1 Mathematical Expressions for SWCC
4.2.2 Soil Water Characteristic Curves for Expansive Soils
4.2.3 Influence of Stress State on Soil Water Characteristic Relationships 8
4.2.4 Effect of Suction on Groundwater Profiles
4.3 Measurement of Matric Suction 90
4.3.1 Tensiometers
4.3.2 Axis Translation Technique
4.2.2.1. Pressure Plate Apparatus
4.2.2.1. Fredlund SWCC Device
4.3.3 Filter Paper Method for Matric Suction
4.3.3.1. Principle of Measurement
4.3.3.2. Calibration Curves
4.3.3.3. Filter Paper Hysteresis
4.3.3.4. Time Required to Reach Equilibrium
4.3.4 Thermal Conductivity Sensors
4.3.5 Electrical Resistance Sensors
4.4 Measurement of Osmotic Suction
4.4.1 Osmotic Tensiometers
4.4.2 Pore Fluid Extraction Technique
4.5 Measurement of Total Suction 1
4.5.1 Psychrometers
4.5.1.1. Thermocouple Pychrometers
4.5.1.2. Chilled Mirror Pychrometers
4.5.2 Filter Paper Method for Total Suction
4.5.2.1. Principle of Measurement
4.5.2.2. Calibration Curves
4.5.2.3. Time Required to Reach Equilibrium
References
5. STATE OF STRESS AND CONSTITUTIVE RELATIONSHIPS
5.1 State of Stress and Stress State Variables
5.2 Stress–Volume Relationships
5.3 Stress–Water Relationships
References
6. OEDOMETER TESTING
6.1 Consolidation-Swell and Constant Volume Tests
6.2 Correction of Oedometer Test Data
6.2.1 Correction for Oedometer Compressibility
6.2.2 Correction for Specimen Disturbance in the CV Test
6.2.3 Effect of the Corrections on Expansion Properties
6.3 Relationship Between CS and CV Swelling Pressures (the m Method)
6.4 Factors Influencing Oedometer Test Results
6.4.1 Initial Stress State Conditions
6.4.2 Soil Fatigue
6.4.3 Initial Consolidation of Sample
6.4.4 Time and Method of Inundation
6.4.5 Storage of Samples
6.4.6 Competency of Laboratory Personnel
References
7. WATER MIGRATION IN EXPANSIVE SOILS
7.1 Water Flow in Unsaturated Soils
7.1.1 Darcy’s Law for Unsaturated Soils
7.1.2 Water Mass Balance Equation
7.1.3 Vertical Seepage in Unsaturated Soil
7.1.4 Flow through Fractured Rocks and Bedding Planes
7.2 Depth and Degree of Wetting
7.2.1 Depth of Wetting
7.2.2 Degree of Wetting
7.2.3 Perched Water Tables in Layered Strata
7.2.4 Wetting Profiles
7.3 Determination of Final Water Content Profiles for Design
7.3.1 Hand Calculation of Final Water Contents for Design
7.3.2 Computer Modeling of Water Migration
7.4 Challenges in Water Migration Modeling for Expansive Soils
References
8. COMPUTATION OF PREDICTED HEAVE
8.1 Oedometer Methods
8.1.1 The Heave Equation
8.1.2 Computation of Free-Field Heave
8.1.3 Computation of Heave under an Applied Load
8.1.4 Computation of Design Heave
8.1.5 Discussion of Earlier Oedometer Methods Proposed to Compute Heave
8.1.5.1. Department of the Army (1983)
8.1.5.2. Fredlund ( 1983)
8.1.5.3. Nelson and Miller ( 1992)
8.1.6 Comments on the Heave Index
8.2 Soil Suction Methods
8.2.1 McKeen (1992)
8.2.2 Department of the Army (1983)
8.2.3 Hamberg and Nelson (1984)
8.2.4 Lytton (1994)
8.3 Empirical Methods
8.4 Progression of Heave with Time
8.4.1 Hyperbolic Equation
8.4.2 Use of Water Migration Modeling to Analyze Rate of Heave
8.5 Free-Field Surface Movement for Shrink–Swell Soils
8.6 Discussion of Heave Prediction
References
9. GENERAL CONSIDERATIONS FOR FOUNDATION AND FLOOR DESIGN
9.1 Risk and Life Cycle Costs
9.1.1 Classification of Expansion Potential
9.1.2 Risk Factor
9.2 Foundation Alternatives
9.3 Factors Influencing Design of Structures on Expansive Soils
9.3.1 Tolerable Foundation Movement
9.3.2 Design Life
9.3.3 Design Active Zone and Degree of Wetting
9.3.4 Site Grading
9.4 Remedial Measures
References
10. SOIL TREATMENT AND MOISTURE CONTROL
10.1 Overexcavation and Replacement
10.2 Prewetting Method
10.3 Chemical Admixtures
10.3.1 Lime Treatment
10.3.2 Cement Treatment
10.3.3 Fly Ash Treatment
10.3.4 Chemical Injection
10.4 Moisture Control Alternatives
10.4.1 Moisture Barriers
10.4.2 Subsurface Drains
10.4.3 Surface Grading and Drainage
10.5 Summary of Soil Treatment Methods
References
11. DESIGN METHODS FOR SHALLOW FOUNDATIONS
11.1 Spread Footing Foundations
11.1.1 Computation of Footing Heave
11.1.2 Spread Footing Design Examples
11.2 Stiffened Slab Foundations
11.2.1 Edge Heave and Center Heave
11.2.2 Differential Heave
11.3 Remedial Measures for Shallow Foundations
11.3.1 Footing Foundations
11.3.2 Stiffened Slab-on-Grade
11.3.3 Other Methods
References
12. DESIGN METHODS FOR DEEP FOUNDATIONS
12.1 Pier and Grade Beam Foundation
12.1.1 Design Methods
12.1.2 Load-Bearing Capacity
12.2 Patented Piers
12.2.1 Helical Piles
12.2.2 Micropiles
12.2.3 Push Piers
12.3 Deep Foundation Design Examples
12.3.1 Rigid Pier Design Example
12.3.2 APEX Design Example
12.3.3 Helical Pile Design Example
12.4 Remedial Measures for Deep Foundations
12.4.1 Pier and Grade Beam Foundation
12.4.2 Underpinning
References
13. FLOORS AND EXTERIOR FLATWORK
13.1 Slabs-on-Grade
13.2 Stiffened Slabs
13.3 Structural Floors
13.4 Exterior Slabs and Flatwork
13.5 Remediation Techniques
13.5.1 Structural Floor Systems
13.5.2 Moisture Control
13.5.3 Chemical Injection
13.5.4 Isolation of the Slab
13.5.5 Exterior Slabs
References
14. LATERAL PRESSURE ON EARTH RETAINING STRUCTURES
14.1 Computation of Lateral Pressure from Expansive Soils
14.2 Testing for Measuring Lateral Swelling Pressure
14.3 Reduction of Lateral Swelling Pressure
14.4 Design for Lateral Earth Pressure
References
Index