Effective stress Class no 1
Curriculum
- 5 Sections
- 9 Lessons
- 10 Weeks
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- Module 1Nature of soil and functional relationships: Introduction to soil mechanics – Soil types – Major soil deposits of India - 3 phase system – Basic soil properties: Void ratio, porosity, degree of saturation, air content, water content, specific gravity, unit weight - Relationship between basic soilproperties - Numerical problems Determination of Water content by oven drying, Specific gravity using pycnometer & specific gravity bottle - Determination of Field density by sand replacement method & Core Cutter method- Numerical problems Soil Structure and their effects on the basic soil properties – Sensitivity and Thixotropy2
- Module 2Index properties: Sieve analysis – Well graded, poorly graded and gap graded soils - Stoke’s law– Hydrometer analysis [no derivation required for percentage finer and diameter] – RelativeDensity - Numerical problems - Consistency – Atterberg Limits and indices – Plasticity charts -laboratory tests for Liquid Limit, Plastic Limit & Shrinkage Limit - Numerical problems IS classification of soil - Numerical problems Permeability of soils: Darcy’s law – Factors affecting permeability – Laboratory tests: Constanthead and falling head permeability tests - Numerical problems - Average permeability of stratified deposits - numerical problems2
- Module 3Principle of effective stress - Total, neutral and effective stress – Pressure diagrams – Numerical problems - Pressure diagrams in soils saturated by capillary action – Quick sand condition –Critical hydraulic gradient Stress distribution: Introduction - Boussinesq’s equations for vertical pressure due to point loadsand line loads – Assumptions and Limitations - Numerical problems - Vertical pressure due touniformly distributed loads beneath strip, circular and rectangular shapes [no derivation required] -Numerical problems Approximate methods for vertical stress-distribution of contact pressure beneath footings : Equivalent Point Load method & 2:1 Distribution Method - Numerical problems - Pressure Isobars- Pressure bulbs – Newmark’s charts (Construction procedure not required) and their use.2
- Module 4Consolidation - Definition – Concepts of Coefficient of compressibility and volume compressibility - e-log p curve - Compression index, Recompression index and Pre consolidationPressure - Normally consolidated, over consolidated and under consolidated soils - Estimation of magnitude of settlement of normally consolidated clays - Numerical problems Terzaghi’s theory of one-dimensional consolidation (no derivation required) - average degree ofconsolidation – Time factor - Coefficient of consolidation - Numerical problems – Laboratoryconsolidation test – Determination of Coefficient of Consolidation - Practical Applications Compaction of soils - Difference between consolidation and compaction - IS Light & Heavy Compaction Tests – OMC and MDD - Zero Air voids line - Numerical problems - Control of compaction - Field compaction methods - Proctor needle for field control2
- Module 5Shear strength of soils- Practical Applications - Mohr-Coulomb failure criterion - Mohr circle method for determination of principal planes and stresses– relationship between shear parametersand principal stresses - Numerical problems Brief discussion of Laboratory tests - Triaxial compression test - UU, CU and CD tests - Total andeffective stress strength parameters - Unconfined compression test, Direct shear test and vane sheartest – Applicability - Numerical problems Stability of finite slopes - Toe failure, base failure, slip failure - Swedish Circle Method : =0 analysis and c- analysis - Friction circle method - Taylor’s Stability number - Stability charts -Numerical Problems1
