basic geotechnical engineering
Semester : V
Course Code : 18CV54
CIE Marks : 40 SEE Marks : 60
Module – 1
Module – 2
Module – 3
Module – 4
Module – 5
BASIC GEOTECHNICAL ENGINEERING
Introduction: Origin and formation of soil, Regional soil deposits in India, Phase Diagram, phase relationships, definitions and their interrelationships. Determination of Index properties: Specific gravity, water content, in-situ density, relative density, particle size analysis(sieve and Hydrometer analysis) Atterberg’s Limits, consistency indices. The activity of clay, Field identification tests, Plasticity chart, BIS soil classification (IS: 1498-1970).
Soil Structure and Clay Mineralogy Single grained, honeycombed, flocculent and dispersed structures, Valence bonds, Soil-Water system, Electrical diffuse double layer, adsorbed water, base-exchange capacity, Isomorphous substitution. Common clay minerals in the soil and their structures- Kaolinite, Illite and Montmorillonite and their application in Engineering
Compaction of Soils: Definition, Principle of compaction, Standard and Modified proctor’s compaction tests, factors affecting compaction, the effect of compaction on soil properties, Field compaction control-compactive effort & method of compaction, lift thickness and number of passes, Proctor’s needle, Compacting equipment and their suitability
Flow through Soils:
Darcy’s law-assumption and validity, coefficient of permeability and its determination (laboratory and field), factors affecting permeability, permeability of stratified soils, Seepage v e l o c i t y , superficial velocity and coefficient of percolation, Capillary Phenomena.
Laplace equation, assumptions, limitation sand its derivation. Flow nets-characteristics and applications. Flow nets for sheet piles and below the dam section. Unconfined flow, phreaticline (Casagrande’s method–with and without toe filter), flow through dams, design of dam filters.
Effective Stress Analysis:
Geostatic stresses, Effective stress concept-total stress, effective stress and Neutral stress and impact of the effective stress in construction of structures, quick sand phenomena
Shear Strength of Soil: Concept of shear strength, Mohr-Coulomb Failure Criterion, Modified Mohr-Coulomb Criterion Total and effective shear strength parameters, factors affecting shear strength of soils. Thixotrophy and sensitivity, Measurement of shear strength parameters – Direct shear test, unconfined compression test, triaxial compression test and field Vane shear test, Test under different drainage conditions.
Consolidation of Soil: Definition, Mass-spring analogy, Terzaghi’s one-dimensional consolidation theory-assumptions and limitations.GoverningdifferentialEquation and solution (No derivation).
Consolidation characteristics of soil (Cc, av, mv and Cv). Laboratory one-dimensional consolidation test, characteristics of e-log (σ’) curve, Pre-consolidation pressure and its determination by Casagrande’s method. Over consolidation ratio, normally consolidated, under consolidated and overconsolidated soils.
Determination of consolidation characteristics of soils- compression index and coefficient of consolidation (square root of time fitting method, logarithmic time fitting method). Primary and secondary consolidation.