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  • INTRODUCTION OF SOIL MECHANICS
    • GEOTECHNICAL LESSONS FROM FAILURES
    • BASIC GEOLOGY
    • INTRODUCTION OF SOILS INVESTIGATION
    • PHASE RELATIONSHIPS
    • Importance of soil compaction
    • HEAD AND PRESSURE VARIATION IN A FLUID AT REST
    • GEOLOGICAL CHARACTERISTICS AND PARTICLE SIZES OF SOILS
    • Composition of the Earth’s Crust
    • PHASES OF A SOILS INVESTIGATION
    • PHYSICAL STATES AND INDEX PROPERTIES OF FINE-GRAINED SOILS
    • INTERPRETATION OF PROCTOR TEST RESULTS
    • DARCY’S LAW
    • COMPOSITION OF SOILS
    • SOILS EXPLORATION PROGRAM
    • DETERMINATION OF THE LIQUID, PLASTIC, AND SHRINKAGE LIMITS
    • SOIL CLASSIFICATION SCHEMES
    • FIELD COMPACTION
    • FLOW PARALLEL TO SOIL LAYERS
    • Surface Forces and Adsorbed Water
    • Soil Identifi cation in the Field
    • DETERMINATION OF THE HYDRAULIC CONDUCTIVITY
    • DETERMINATION OF PARTICLE SIZE OF SOILS
    • Soil Sampling
    • Falling-Head Test
    • Particle Size of Fine-Grained Soils
    • Groundwater Conditions
    • Pumping Test to Determine the Hydraulic Conductivity
    • COMPARISON OF COARSE-GRAINED AND FINE-GRAINED SOILS
    • Types of In Situ or Field Tests
    • GROUNDWATER LOWERING BY WELLPOINTS

  • SOIL WATER AND WATER FLOW
    • STRESSES AND STRAINS
    • STRESS AND STRAIN INVARIANTS
    • IDEALIZED STRESS–STRAIN RESPONSE AND YIELDING
    • Hooke’s Law Using Stress and Strain Invariants
    • PLANE STRAIN AND AXIAL SYMMETRIC CONDITIONS
    • STRESS PATHS
    • Axisymmetric Condition
    • Plotting Stress Paths Using Two-Dimensional Stress Parameters
    • ANISOTROPIC, ELASTIC STATES
    • Mohr’s Circle for Stress States
    • Mohr’s Circle for Strain States
    • The Principle of Effective Stress
    • Effective Stresses Due to Geostatic Stress Fields
    • Effects of Capillarity
    • Effects of Seepage
    • LATERAL EARTH PRESSURE AT REST
    • STRESSES IN SOIL FROM SURFACE LOADS
    • Strip Load
    • Uniformly Loaded Rectangular Area
    • Vertical Stress Below Arbitrarily Shaped Areas

  • STRESS DISTRIBUTIONCOMPRESSIBILITY AND SETTLEMENT
    • BASIC CONCEPTS
    • TYPICAL RESPONSE OF SOILS TO SHEARING FORCES
    • BASIC CONCEPTS
    • Consolidation Under a Constant Load—Primary Consolidation
    • Effects of Increasing the Normal Effective Stress
    • Soil Yielding
    • Void Ratio and Settlement Changes Under a Constant Load
    • Effects of Soil Tension
    • Primary Consolidation Parameters
    • Coulomb’s Failure Criterion
    • CALCULATION OF PRIMARY CONSOLIDATION SETTLEMENT
    • Taylor’s Failure Criterion
    • Procedure to Calculate Primary Consolidation Settlement
    • Mohr–Coulomb Failure Criterion
    • ONE-DIMENSIONAL CONSOLIDATION THEORY
    • PRACTICAL IMPLICATIONS OF THE FAILURE CRITERIA
    • Solution of Governing Consolidation Equation Using Fourier Series
    • INTERPRETATION OF THE SHEAR STRENGTH OF SOILS
    • Finite Difference Solution of the Governing Consolidation Equation
    • LABORATORY TESTS TO DETERMINE SHEAR STRENGTH PARAMETERS
    • SECONDARY COMPRESSION SETTLEMENT
    • Conventional Triaxial Apparatus
    • Oedometer Test
    • Unconfi ned Compression (UC) Test
    • Determination of the Coeffi cient of Consolidation
    • Consolidated Undrained (CU) Compression Test
    • Determination of the Past Maximum Vertical Effective Stress
    • POREWATER PRESSURE UNDER AXISYMMETRIC UNDRAINED LOADING
    • PRECONSOLIDATION OF SOILS USING WICK DRAINS
    • OTHER LABORATORY DEVICES TO MEASURE SHEAR STRENGTH
    • Hollow-Cylinder Apparatus
    • FIELD TESTS

  • SHEAR STRENGTH
    • ALLOWABLE STRESS AND LOAD AND RESISTANCE FACTOR DESIGN
    • COLLAPSE LOAD USING THE LIMIT EQUILIBRIUM METHOD
    • Prediction of the Behavior of Coarse-Grained Soils Using CSM
    • BEARING CAPACITY EQUATIONS
    • ELEMENTS OF THE CRITICAL STATE MODEL
    • MAT FOUNDATIONS
    • FAILURE STRESSES FROM THE CRITICAL STATE MODEL
    • BEARING CAPACITY OF LAYERED SOILS
    • Undrained Triaxial Test
    • SETTLEMENT CALCULATIONS
    • MODIFICATIONS OF CSM AND THEIR PRACTICAL IMPLICATIONS
    • Primary Consolidation Settlement
    • RELATIONSHIPS FROM CSM THAT ARE OF PRACTICAL SIGNIFICANCE
    • DETERMINATION OF BEARING CAPACITY AND SETTLEMENT OF COARSE-GRAINED SOILS
    • Relationships Among the Tension Cutoff, Mean Effective Stress, and Preconsolidation Stress
    • Cone Penetration Test (CPT)
    • Relationships Among Undrained Shear Strength, Critical State Friction Angle, and Preconsolidation Ratio
    • Plate Load Test (PLT)
    • Relationship Between the Normalized Undrained Shear Strength of One-Dimensionally Consolidated or Ko-Consolidated and Isotropically
    • SHALLOW FOUNDATION ANALYSIS USING CSM
    • Relationship Between the Normalized Undrained Shear Strength at Initial Yield and at Critical State for Overconsolidated Fine-Grained Soils Under Triaxial Test Condition
    • Dense, Coarse-Grained Soils
    • Relationship Between Direct Simple Shear Tests and Triaxial Tests
    • Relationship for the Application of Drained and Undrained
    • Relationship Among Excess Porewater Pressure, Preconsolidation Ratio, and Critical State Friction Angle
    • Undrained Shear Strength, Liquidity Index, and Sensitivity
    • SOIL STIFFNESS
    • STRAINS FROM THE CRITICAL STATE MODEL
    • Shear Strains
    • CALCULATED STRESS–STRAIN RESPONSE
    • APPLICATION OF CSM TO CEMENTED SOILS

  • SLOPE STABILITY
    • TYPES OF PILES AND INSTALLATION
    • TWO-DIMENSIONAL FLOW OF WATER THROUGH POROUS MEDIA
    • BASIC CONCEPTS OF LATERAL EARTH PRESSURES
    • SOME CAUSES OF SLOPE FAILURE
    • Pile Installation
    • FLOWNET SKETCHING
    • COULOMB’S EARTH PRESSURE THEORY
    • Construction Activities
    • LOAD CAPACITY OF SINGLE PILES
    • INTERPRETATION OF FLOWNET
    • RANKINE’S LATERAL EARTH PRESSURE FOR A SLOPING BACKFILL AND A SLOPING WALL FACE
    • INFINITE SLOPES
    • PILE LOAD TEST (ASTM D 1143)
    • FLOW THROUGH EARTH DAMS
    • LATERAL EARTH PRESSURES FOR A TOTAL STRESS ANALYSIS
    • ROTATIONAL SLOPE FAILURES
    • METHODS USING STATICS FOR DRIVEN PILES
    • SOIL FILTRATION
    • APPLICATION OF LATERAL EARTH PRESSURES TO RETAINING WALLS
    • METHOD OF SLICES
    • PILE LOAD CAPACITY OF DRIVEN PILES BASED ON SPT AND CPT RESULTS
    • TYPES OF RETAINING WALLS AND MODES OF FAILURE
    • APPLICATION OF THE METHOD OF SLICES
    • LOAD CAPACITY OF DRILLED SHAFTS
    • STABILITY OF RIGID RETAINING WALLS
    • PROCEDURE FOR THE METHOD OF SLICES
    • PILE GROUPS
    • STABILITY OF FLEXIBLE RETAINING WALLS
    • STABILITY OF SLOPES WITH SIMPLE GEOMETRY
    • ELASTIC SETTLEMENT OF PILES
    • Analysis of Sheet Pile Walls in Mixed Soils
    • CONSOLIDATION SETTLEMENT UNDER A PILE GROUP
    • BRACED EXCAVATION
    • SETTLEMENT OF DRILLED SHAFTS
    • MECHANICAL STABILIZED EARTH WALLS
    • PILE-DRIVING FORMULAS AND WAVE EQUATION
    • OTHER TYPES OF RETAINING WALLS
    • LATERALLY LOADED PILES
    • MICROPILES

Branch : Civil Engineering
Subject : Soil Mechanics
Unit : INTRODUCTION OF SOIL MECHANICS

Soil Sampling


Description:

The objective of soil sampling is to obtain soils of satisfactory size with minimum disturbance for observations and laboratory tests. Soil samples are usually obtained by attaching an open-ended, thin-walled tube—called a Shelby tube or, simply, a sampling tube—to drill rods and forcing it down into the soil. The tube is carefully withdrawn, hopefully with the soil inside it. Soil disturbances occur from several sources during sampling, such as friction between the soil and the sampling tube, the wall thickness of the sampling tube, the sharpness of the cutting edge, and the care and handling of the sample tube during transportation.


To minimize friction, the sampling tube should be pushed instead of driven into the ground. Sampling tubes that are in common use have been designed to minimize sampling disturbances. One measure of the effects of sampler wall thickness is the recovery ratio defi ned as L/z, where L is the length of the sample and z is the distance that the sampler was pushed. Higher wall thickness leads to a greater recovery ratio and greater sampling disturbance. One common type of soil sampler is the “Shelby tube,” which is a thin-walled, seamless steel tube of diameter 50 or 75 mm and length of 600–900 mm .

 

 

Another popular sampler is the “standard” sampler, also known as the split spoon sampler (split barrel sampler), which has an inside diameter of 35 mm and an outside diameter of 51 mm . The sampler has a split barrel that is held together using a screw-on driving shoe at the bottom end and a cap at the upper end. In some

 

 

 

 

 

a) A thin-walled tube and (b) A split barrel sampler

 

 

 

 

countries a steel liner is used inside the sampler, but in the United States it is standard practice not to use this liner. Consequently, the soil sample has a greater diameter. The results of SPT  are different for lined and unlined samplers. The thicker wall of the standard sampler permits higher driving stresses than the Shelby tube, but does so at the expense of higher levels of soil disturbances. Split spoon samples are disturbed. They are used for visual examination and for classifi cation tests.

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