Soil Mechanics

Origin and classification of soils Introduction: what is soil mechanics? Structure of the earth Origin of soils Soil mineralogy Phase relationships for soils Unit weight Effective stress Particle size distributions Soil filters Soil description Index tests and classification of clay soils Compaction Houses built on clay Key points Self-assessment and Learning Questions Origins and mineralogy of soils Phase relationships, unit weight and calculation of effective stresses Particle size analysis and soil filters Index tests and classification Compaction Notes References Soil strength Introduction Stress analysis Soil strength Friction Shearbox or direct shear apparatus Presentation of shearbox test data in engineering units Volume changes during shear Critical states Peak strengths and dilation Shearbox tests on clays Applications Stress states in the shearbox test Simple shear apparatus Key points Self-assessment and learning questions Shearbox test Development of a critical state model Determination of peak strengths Use of strength data to calculate friction pile load capacity Stress analysis and interpretation of shearbox test data References Groundwater flow and control Introduction Pore water pressures in the ground Darcy's law and soil permeability Laboratory measurement of permeability Field measurement of permeability Permeability of laminated soils Mathematics of groundwater flow Plane flow Confined flownets Calculation of pore water pressures using flownets Quicksand Unconfined flownets Distance of influence Soils with anisotropic permeability Zones of different permeability Boundary conditions for flow into drains Application of well pumping formulae to construction dewatering Numerical methods Groundwater control Unsaturated soils Key points Self-assessment and learning questions Laboratory measurement of permeability fluidisation layered soils Well pumping test for field measurement of permeability Confined flownets and quicksand Unconfined flownet Flownets in anisotropic soils Notes References One-dimensional compression and consolidation Introduction and objectives One-dimensional compression: the oedometer test One-dimensional consolidation Properties of isochrones One-dimensional consolidation: solution using parabolic isochrones Determining the consolidation coefficient cv from oedometer test data Application of consolidation testing and theory to field problems One-dimensional consolidation: exact solutions Radial drainage Limitations of the simple models for the behaviour of soils in one-dimensional compression and consolidation Key points Self-assessment and learning questions Analysis and interpretation of one-dimensional compression test data Analysis of data from the consolidation phase Application of one-dimensional compression and consolidation theory to field problems Notes References Triaxial test and soil behaviour Introduction Triaxial test Stress parameters Stress analysis of the triaxial test Determining the effective angle of shearing resistance phi' from triaxial shear tests Undrained shear strengths of clay soils Isotropic compression and swelling Specimen preparation by one-dimensional compression and swelling: K consolidation Conditions imposed in shear tests Critical states Yield State paths during shear: normally consolidated and lightly overconsolidated clays Peak strengths Residual strength Sensitive soils Correlation of critical state parameters with index tests Creep Anisotropy Unsaturated soils Critical state model applied to sands Non-linear soil models Repeated or cyclic loading Key points Self-assessment and learning questions Interpretation of triaxial test results Determination of critical state and Cam clay parameters Analysis and prediction of state paths using Cam clay concepts Notes References Calculation of soil settlements using elasticity methods Introduction Selection of elastic parameters Boussinesq's solution Newmark's chart and estimation of vertical stress Settlements due to surface loads and foundations Influence factors for stress Standard solutions for surface settlements on an isotropic, homogeneous, elastic half-space Estimation of immediate settlements Effect of heterogeneity Cross-coupling of shear and volumetric effects due to anisotropy Key points Self-assessment and learning questions Determining elastic parameters from laboratory test data Calculation of increases in vertical effective stress below a surface surcharge Calculation of increases in vertical effective stress and resulting soil settlements Use of standard formulae in conjunction with one-dimensional consolidation theory References Plasticity and limit equilibrium methods for earth pressures and retaining walls Engineering plasticity Upper and lower bounds (safe and unsafe solutions) Failure criteria for soils Retaining walls Calculation of limiting lateral earth pressures Development of simple stress field solutions for a propped embedded cantilever retaining wall Soil/wall friction Mechanism-based kinematic and equilibrium solutions for gravity retaining walls Reinforced soil walls Compaction stresses behind backfilled walls Key points Self-assessment and learning questions Calculation of lateral earth pressures and prop loads Stress field limit equilibrium analysis of an embedded retaining wall Mechanism-based limit equilibrium analysis of retaining walls Reinforced soil retaining walls Compaction stresses References Foundations and slopes Introduction and objectives Shallow strip foundations (footings): simple lower bound (safe) solutions Simple upper bound (unsafe) solutions for shallow strip footings Bearing capacity enhancement factors to account for foundation shape and depth, and soil weight Shallow foundations subjected to horizontal and moment loads Simple piled foundations: ultimate axial loads of single piles . -crit or-peak Pile groups and piled rafts Lateral loads on piles Introductory slope stability: the infinite slope Analysis of a more general slope Laterally loaded piles for slope stabilisation Key points Self-assessment and learning questions Shallow foundations Deep foundations Laterally loaded piles Slopes References In-ground retaining structures: embedded walls and tunnels Introduction and objectives Earth pressure coefficients taking account of shear stresses at the soil/wall interface Limit equilibrium calculations for embedded retaining walls and ultimate limit state design Calculation of bending moments and prop loads: serviceability limit states Embedded walls retaining clay soils Geostructural mechanism to estimate wall movements Effect of relative soil: wall stiffness Strip loads Multi-propped embedded walls Tunnels Key points Self-assesment and learning questions Embedded retaining walls and ULS design Tunnels Note References Calculation of improved bearing capacity factors and earth pressure coefficients using plasticity methods Introduction and objectives Stress discontinuities and their use to calculate improved bearing capacity factors for a shallow foundation subjected to a vertical load: effective stress (phi') analysis Stress discontinuities and their use to calculate improved bearing capacity factors for a shallow foundation subjected to a vertical load: total stress (tauu) analysis Application to stress analysis Shallow foundations subjected to inclined loads Calculation of earth pressure coefficients for rough retaining walls Sloping backfill Wall with a sloping (battered) back Improved upper bounds for shallow foundations Key points Self assesment and learning questions Bearing capacity of foundations Retaining walls and earth pressures References Site investigation, in situ testing and modelling Introduction and objectives Site investigation In situ testing Modelling Ground improvement Key points Self-assessment and learning questions In situ testing Modelling Ground improvement Notes References Index