GEOTECHNICAL ENGINEERING UNSATURATED AND SATURATED SOILS

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1 GEOTECHNICAL ENGINEERING UNSATURATED AND SATURATED SOILS By Jean-Louis BRIAUD Units Acknowledgements 1. INTRODUCTION 1.1. Why this book 1.2. Geotechnical engineering 1.3. The past and the future 1.4. Some recent and notable projects 1.5. Failures may occur 1.6. Our work is buried 1.7. Geotechnical engineering can be fun 1.8. Units 1.9. Problems and solutions 2. ENGINEERING GEOLOGY 2.1. Definition 2.2. The Earth 2.3. Geologic Time 2.4. Rocks 2.5. Soils 2.6. Geological features 2.7. Geologic maps 2.8. Ground water 2.9. Problems and solutions 3. SOIL COMPONENTS 3.1. Particles, liquid, and gas 3.2. Particle size, shape, and color 3.3. Composition of gravel, sand, and silt particles 3.4. Composition of clay and silt particles 3.5. Particle behavior 3.6. Soil structure 3.7. Three phase diagram 3.8. Weight volume parameters 3.9. Measurement of the weight volume parameters 1

2 3.10. Solving a weigh volume problem Problems and solutions 4. CLASSIFICATION TESTS AND CLASSIFICATIONS 4.1. Sieve analysis 4.2. Hydrometer analysis 4.3. Atterberg limits and other limits 4.4. Classification parameters 4.5. Engineering significance of classification parameters and plasticity chart 4.6. Unified Soil Classification System USCS 4.7. Problems and solutions 5. ROCKS AND INTERMEDIATE GEOMATERIALS 5.1. Rock groups and identification 5.2. Rock mass vs. rock substance 5.3. Rock discontinuities 5.4. Rock index properties 5.5. Rock engineering properties 5.6. Rock mass rating 5.7. Rock engineering problems 5.8. Permafrost 5.9. Problems and solutions 6. SITE INVESTIGATION, DRILLING, AND SAMPLING 6.1. General 6.2. Preliminary site investigation 6.3. Number and depth of borings and in-situ tests 6.4. Drilling Wet rotary drilling method Hollow stem auger drilling method 6.5. Sampling Sample disturbance Common sampling methods 6.6. Ground water level 6.7. Field identification and boring logs 6.8. Soil names 6.9. Offshore site investigations Offshore geophysical investigations Offshore geotechnical drilling Offshore geotechnical sampling Problems and solutions 7. IN SITU TESTS 2

3 7.1. Standard Penetration Test (SPT) 7.2. Cone Penetration Test (CPT) 7.3. Pressuremeter Test (PMT) 7.4. Dilatometer test (DMT) 7.5. Vane shear test (VST) 7.6. Borehole shear test (BST) 7.7. Plate load test (PLT) 7.8. California Bearing Ratio Test (CBR) 7.9. Pocket penetrometer, torvane test Pocket erodometer test Compaction control tests Sand cone test (SCT) Rubber balloon test (RBT) Nuclear density/water content test (NDWCT) Field oven test (FOT) Lightweight deflectometer test (LWDT) BCD test (BCDT) Hydraulic conductivity field tests (HCT) The borehole tests The cone penetrometer dissipation test (CPDT) The sealed double ring infiltrometer test (SDRIT) The two stage borehole permeameter test (TSBPT) Offshore in situ tests Problems and solutions 8. ELEMENTS OF GEOPHYSICS 8.1. General 8.2. Seismic Techniques Seismic waves Seismic reflection Seismic refraction Cross hole test, seismic cone test, seismic dilatometer test Spectral Analysis of Surface Waves (SASW) 8.3. Electrical resistivity techniques Background on electricity Resistivity tomography 8.4. Electromagnetic methods Electromagnetic waves Ground penetrating radar (GPR) Time Domain Reflectometry (TDR) 8.5. Remote sensing techniques Lidar Satellite imaging 8.6. Problems and solutions 3

4 9. LABORATORY TESTS 9.1. General 9.2. Measurements Normal stress or pressure Shear stress Water compression stress Water tension stress Normal strain Shear strain Bender elements 9.3. Compaction Test Dry unit weight Saturated Soils Unsaturated Soils 9.4. Compaction Test Soil modules Saturated Soils Unsaturated Soils 9.5. Consolidation Test Saturated Soils Unsaturated Soils 9.6. Swell Test Saturated Soils Unsaturated Soils 9.7. Shrink Test Saturated Soils Unsaturated Soils 9.8. Collapse Test Saturated Soils Unsaturated Soils 9.9. Direct Shear Test Saturated Soils Unsaturated Soils Simple Shear Test Saturated Soils Unsaturated Soils Unconfined Compression Test Saturated Soils Unsaturated Soils Triaxial Test Saturated Soils Unsaturated Soils Resonant Column Test Saturated Soils Unsaturated Soils Lab Vane Test 4

5 Saturated Soils Unsaturated Soils Soil Water Retention Curve (Soil Water Characteristic Curve) Test Saturated Soils Unsaturated Soils Constant Head Permeameter Test Saturated Soils Unsaturated Soils Falling Head Permeameter Test for Saturated Soils Wetting Front Test for Unsaturated Soils Air Permeability Test for Unsaturated Soils Erosion Test Saturated Soils Unsaturated Soils Problems and solutions 10. EFFECTIVE STRESS, WATER STRESS, AIR STRESS AND STRAINS General Stress vector, normal stress, shear stress, stress tensor Sign convention for stresses and strains Calculating stresses on any plane: equilibrium equations for two dimensional analysis Calculating stresses on any plane: Mohr circle for two dimensional analysis Mohr circle in three dimensions Stress invariants Displacements Normal strain, shear strain, strain tensor Cylindrical coordinates and spherical coordinates Stress-strain curves Stresses in the three soil phases Effective stress (unsaturated soils) Effective stress (saturated soils) Area ratio factors α and β Water stress profiles Water tension, suction Matric suction Contractile skin Osmotic suction Relationship between total suction and relative humidity Trees Precision on water content and water tension Stress profile at rest in unsaturated soils Soil Water Retention Curve Independent Stress State variables Problems and solutions 5

6 11. PROBLEM SOLVING METHODS General Drawing to scale as a first step Available laws Continuum Mechanics Methods Solving a failure problem limit equilibrium, method of characteristics, lower and upper bound theorems Examples of solving a failure problem Solving a deformation problem Example of solving a deformation problem Solving a flow problem Example of solving a flow problem Numerical Simulation Methods (FDM, FEM, DEM, BEM) Finite difference method Examples of finite difference solution Finite element method Example of finite element solution Boundary element method Discrete element method Example of discrete element solution Probability and Risk Analysis Background Procedure for probability approach Risk and acceptable risk Example of probability approach Regression analysis Basic concepts Example of regression analysis Artificial neural network method General methodology for ANN ANN Example Dimensional analysis Buckingham theorem Examples of dimensional analysis Similitude laws for experimental simulations Similitude laws Example of similitude laws application for a scaled model Example of similitude laws application for a centrifuge model Types of Analyses (drained undrained, effective stress total stress, short term long term) Problems and solutions 12. SOIL CONSTITUTIVE MODELS Elasticity 6

7 Elastic model Example of use of elastic model Linear viscoelasticity Simple models: Maxwell and Kelvin-Voigt models General linear viscoelasticity Plasticity Some yield functions and yield criterions Example of use of yield criterions Plastic potential function and flow rule Hardening, softening rule Example of application of plasticity method Common models Duncan-Chang hyperbolic model Modified Cam Clay model Barcelona Basic model Water stress predictions Problems and solutions 13. FLOW OF FLUID AND GAS THROUGH SOILS General Flow of water in a saturated soil Discharge velocity, seepage velocity, conservation of mass Heads Hydraulic gradient Darcy s Law is the constitutive law Hydraulic conductivity Field vs. Lab value of hydraulic conductivity Seepage force Quick sand condition and critical hydraulic gradient Quick clay Sand liquefaction Two dimensional flow problem Drawing a flow net for homogeneous soil Properties of a flow net for homogeneous soil Calculations associated with flow nets Flow net for hydraulically anisotropic soil Flow and flow net for layered soils Flow of water and air in unsaturated soil Hydraulic conductivity for water and for air One dimensional flow Three dimensional water flow Three dimensional air flow Problems and solutions 14. DEFORMATION 7

8 14.1. Modulus of deformation general Modulus which one? Modulus influence of state factor Modulus influence of loading factor Modulus differences between fields of application Modulus, modulus of subgrade reaction, and stiffness Common values of Young s modulus and Poisson s ratio Correlations with other tests Modulus, a comprehensive model Initial tangent modulus Go or Gmax Reduction of Gmax with strain, the G/Gmax curve Preconsolidation pressure and overconsolidation ratio from consolidation test Compression index, recompression index, secondary compression index from consolidation test Time effect from consolidation test Modulus, time effect, cyclic effect from the pressuremeter test Resilient modulus for pavements Unsaturated soils, effect of drying and wetting on the modulus Shrink-swell deformation behavior, shrink-swell modulus Collapse deformation behavior Problems and solutions 15. SHEAR STRENGTH General Basic experiments Stress strain curve, water stress response, and stress path Shear strength envelope Unsaturated soils Experimental determination of shear strength (lab tests, in situ tests) Estimating effective stress shear strength parameters Undrained shear strength of saturated fine grained soils The ratio su/σov and the SHANSEP method Undrained shear strength for unsaturated soils Pore pressure parameters A and B Estimating undrained shear strength values Residual strength parameters and sensitivity Strength profiles Types of analyses Transformation from effective stress solution to undrained strength solution Problems and solutions 16. THERMODYNAMICS FOR SOIL PROBLEMS General 8

9 16.2. Definitions Constitutive and fundamental laws Heat conduction theory Axisymmetric heat propagation Thermal properties of soils Multilayer systems Applications Frozen soils Problems and solutions 17. SHALLOW FOUNDATIONS Definitions Case history Definitions and design strategy Limit states, load and resistance factors, factor of safety General behavior Ultimate bearing capacity Direct strength equations Terzaghi s ultimate bearing capacity equation Layered soils Special loading Ultimate bearing capacity of unsaturated soils Load Settlement Curve Approach Settlement General behavior Elasticity approach for homogeneous soils Elasticity approach for layered soils Chart approach General approach Zone of influence Stress increase with depth Choosing a stress strain curve, setting up the calculations, Consolidation settlement: magnitude Consolidation settlement: time rate Creep settlement Bearing pressure values Shrink-swell movement, swelling pressures, collapse movement Water content or water tension vs. strain curve Shrink-swell movement calculation methods Step by step procedure Case history Foundations on shrink swell soils Types of foundations on shrink swell soils Design method for stiffened slabs on grade Tolerable movements 9

10 Large mat foundations General principles Example of settlement calculations Two case histories Problems and solutions 18. DEEP FOUNDATIONS Different types Design strategy Pile installation Installation of bored piles NDT testing of bored piles Installation of driven piles Pile driving formulas Wave propagation in a pile Wave equation analysis Information from pile driving measurements (PDA, Case, CAPWAP) Suction caissons Load testing (Static, Statnamic, Osterberg) Vertical load single pile Ultimate vertical capacity for a single pile Miscellaneous questions on the ultimate capacity of a single pile Settlement of a Single Pile Vertical load pile group Ultimate vertical capacity of a pile group Settlement of pile groups Downdrag Definition and behavior Downdrag on a single pile Example downdrag calculations LRFD provisions Downdrag on a group of piles Piles in shrink-swell soils Horizontal load and moment single pile Definitions and behavior Ultimate capacity Displacement and Maximum Moment flexible pile Displacement and Maximum Moment rigid pile Modulus of subgrade reaction Free head and fixed head condition Rate of loading effect Cyclic loading effect P-y curve approach Horizontal loading next to a trench Horizontal load and Moment - pile group 10

11 Overturning moment Ultimate capacity Movement Combined Piled Raft Foundation (CPRF) Problems and solutions 19. SLOPE STABILITY General Design approach Infinite slopes Seepage force in stability analysis Plane surfaces Block analysis Slopes with water in tensile crack Chart methods Taylor chart Spencer chart Janbu chart Morgenstern chart Method of slices Ordinary method of slices (Fellenius, 1927) Bishop simplified method (Bishop, 1955) Generalized equilibrium method (Abramson et al. 2002) Critical failure circle Water stress for slope stability Types of analyses: Progressive failure in strain softening soils Shallow slide failures in compacted unsaturated embankments Reinforced slopes Reinforcement type Factor of safety Probabilistic approach Three dimensional (3D) circular failure analysis Finite element analysis Seismic slope analysis Monitoring Repair methods Landfill slopes see Chapter Slopes involving geosynthetics see Chapter Problems and solutions 20. COMPACTION General Compaction laboratory tests 11

12 20.3. Compaction field tests Compaction and soil type Intelligent roller compaction Soil modulus from vibratory rollers Roller measurements as compaction indices Impact roller compaction Dynamic or drop-weight compaction 21. RETAINING WALLS Different types (top down, bottom up) Active, at rest, passive earth pressure and displacement in between Earth pressure theories Coulomb earth pressure theory (1776) Rankine earth pressure theory (1857) Earth pressure theory by Mohr circle Water in the case of compression stress (saturated) Water in the case of tension stress (unsaturated or saturated) Influence of surface loading (line load, pressure) General case and earth pressure profiles Special case of undrained behavior of fine grained soils At rest earth pressure Earth pressure due to compaction Earth pressures in shrink swell soils Displacements Gravity walls Mechanically stabilized earth walls or MSE walls Cantilever top-down walls Anchored walls and strutted walls Soil nail walls Special case of trenches Problems and solutions 22.. SOIL DYNAMICS AND EARTHQUAKE GEO-ENGINEERING 22.1 Background 22.2 Earthquake magnitude 22.3 Wave propagation 22.4 Dynamic soil properties 22.5 Ground motion 22.6 Seismic hazard analysis 22.7 Ground response analysis One dimensional solution for undamped linear soil and rigid rock One dimensional Solution for damped linear soil on rigid rock Layered soils 22.8 Design parameters 12

13 Site classes A though E for different soil stiffness Code based spectrum Hazard levels 22.9 Liquefaction Phenomenon When to do a liquefaction study When can a soil liquefy? Seismic slope stability Seismic design of retaining walls Seismic design of gravity walls Water pressures on walls during earthquake Seismic design of MSE walls Seismic design of cantilever walls Seismic design of anchored walls Seismic design of foundations Problems and solutions 23. EROSION OF SOILS AND SCOUR PROBLEMS 23.1 The erosion phenomenon 23.2 Erosion models 23.3 Measuring the erosion function 23.4 Soil erosion categories 23.5 Rock erosion 23.6 Water velocity 23.7 Geometry of the obstacle 23.8 Bridge scour Maximum scour depth, zmax, analysis Maximum shear stress at soil water boundary when scour begins Final scour depth, zfinal, analysis for constant velocity flow and uniform soil Final scour depth, zfinal, analysis for a velocity hydrograph and layered soil The Woodrow Wilson Bridge case history (Kwak et al. 2002) 23.9 River meandering River meandering The Brazos River meander case history (Park, 2007) Levee overtopping General methodology New Orleans Katrina hurricane levee case history (Briaud, 2006b) Countermeasures for erosion protection Internal erosion of earth dams The phenomenon Most susceptible soils Criterion to evaluate internal erosion potential Remedial measures Problems and solutions 13

14 24. GEOENVIRONMENTAL ENGINEERING 24.1 Introduction 24.2 Types of wastes and contaminants 24.3 Laws and regulations 24.4 Geochemistry background Chemistry background Geo-chemistry background 24.5 Contamination Contamination sources Contamination detection and site characterization Contaminant transport and fate 24.6 Remediation Risk assessment and strategy In situ waste containment Soil remediation Ground water remediation 24.7 Landfills Waste properties Regulations Liners Covers Leachate collection Landfill slopes Gas generation and management 24.8 Future considerations 24.9 Problems and solutions 25. GEOSYNTHETICS 25.1 General 25.2 Types of geosynthetics 25.3 Properties of geosynthetics Properties of geotextiles Properties of geomembranes Properties of geogrids Properties of geosynthetics clay liners (GCL) Properties of geofoams Properties of geonets 25.4 Design for separation 25.5 Design of liners and covers 25.6 Design for reinforcement Road reinforcement Mechanically Stabilized Earth (MSE) geosynthetic walls Reinforced slopes Reinforced foundations and embankments 14

15 25.7 Design for filtration and drainage 25.8 Design for erosion control 25.9 Other design applications Light weight fills Compressible inclusions Thermal insulation Geosynthetics and landfill slopes Problems and solutions 26. GROUND IMPROVEMENTS 26.1 Overview 26.2 Soil improvement without admixture in coarse grained soils Compaction Dynamic compaction Vibrocompaction Other methods 26.3 Soil improvement without admixture in fine grained soils Displacement replacement Preloading using fill Prefabricated vertical drains and preloading using fill Preloading using vacuum Electro osmosis Hydro-blasting compaction Ground freezing 26.4 Soil improvement with replacement Stone columns without geosynthetic sock Stone columns with geosynthetic encasement Dynamic replacement 26.5 Soil improvement with grouting and admixtures Particulate grouting Chemical grouting Jet grouting Compaction grouting Compensation grouting Mixing method Lime treatment Microbial methods 26.6 Soil improvement with inclusions Mechanically or geosynthetically stabilized Earth Ground anchors and soil nails Geosynthetic mat and column supported embankment 26.7 Selection of soil improvement method 26.8 Problems and solutions 27. TECHNICAL COMMUNICATIONS 15

16 27.1 General s 27.3 Letters 27.4 Geotechnical Reports 27.5 Theses and Dissertations 27.6 Visual Aids for Reports 27.7 Phone Calls 27.8 Meetings 27.9 Presentations and Power Point Slides Media Interaction Ethical Behavior Belong to Your Professional Society Rules for a Successful Career REFERENCES SUBJECT INDEX 16

17 Sociedad Mexicana de Ingeniería Geotécnica, A.C El cimiento de la Ingeniería Mexicana Dear Colleague, As you may know, I have very recently published a book entitled Geotechnical Engineering: Unsaturated and Saturated Soils and I would like to give you a special code (BRI13) which you can use to get 30% off the list price of $165 in case you wish to purchase a copy. The offer expires on 31Dec2013. For more information about the book or to purchase print or e-books go to: If you are a professor or instructor and are interested in contacting your local Wiley sales representative to discuss adopting the book and get an evaluation copy, go to: I also have some dedication cards that I can sign and send to you if you wish to stick the card on to your copy. The book is 1000 pages long with 1300 illustrations and 400 problems with solutions next to the problems at the end of each chapter. I attach the 27 chapter table of contents which will give you a sense of what you can find in the book. It includes the classical topics like lab tests, foundations, retaining walls and slope stability but also geosynthetics, geoenvironmental, soil improvement, earthquake engineering, site investigations, in situ testing, engineering geology, geophysics, erosion, problem solving methods (FDM, FEM, DEM, probability and risk), and even technical communications. I wrote this book over the last three years not only for undergraduate courses but also for most courses offered in geotechnical engineering so that the students would not have to buy several books to cover the topic. I also wrote it for the practitioner as a very helpful reference. In addition to covering the breadth of geotechnical engineering, I wanted to attempt to start with unsaturated soil mechanics and treat saturated soils as a special case rather than the other way around. If you find something you like about the book, please tell others and if you find mistakes, please tell me so that I can address them in subsequent printing of this edition and continue to improve. Best wishes, Jean-Louis. ************************************************ Jean-Louis BRIAUD, PhD, PE Past President of ISSMGE Valle de Bravo 19 Col. Vergel de Coyoacán, México D.F., MÉXICO FAX Web Page: E- Mail: administracion@smig.org.mx

GEOTECHNICAL ENGINEERING UNSATURATED AND SATURATED SOILS

GEOTECHNICAL ENGINEERING UNSATURATED AND SATURATED SOILS By Jean-Louis BRIAUD Units Acknowledgements 1. INTRODUCTION 1.1. Why this book 1.2. Geotechnical engineering 1.3. The past and the future 1.4. Some