DI03006051 · Semester 3 · 5G scheme
Soil Engineering
Notes and solutions following the Gujarat Technological University (GTU) syllabus for DI03006051. Independent material — not issued by the university.
Civil Engineering
Materials
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Syllabus units
Unit 1: Overview of Soil Engineering
- Definition of Soil, Soil Mechanics, Soil Engineering, Importance of Soil engineering
- History of Soil Engineering
- Soil formation in Geological cycle
- List of Structures where soil is used as construction material
- Types of Soil according to mode of Transportation
- Major Soil deposits of India.
Unit 2: Physical and Index properties of Soil
- Soil as a three phase system, assumptions for drawing two phase & three phase diagrams,
- Fundamental definitions of physical properties- Water content, Bulk density, Dry density, Saturated density, Submerged density, Density of solids, Specific gravity-Absolute & Mass specific gravity, void ratio, porosity, Degree of saturation, Air content, Percentage air voids, Relative density
- Derivation of following relations from phase diagrams and numericals on each : 2.3.1 e= n/n-1, n=e/1+e 2.3.2 w×G =e×Sr 2.3.3 ϒd=ϒb/1+w 2.3.4 ϒd=ϒb/1+w 2.3.5 ϒsat= (G+e)ϒw/(1+e) 2.3.6 ϒsub=(G-1)ϒw/(1+e) 2.3.7 ϒd= G ϒw/1+e
- Methods to determine moisture content of soil.
- Determination of Bulk & Dry density of soil by Core Cutter method and Sand Replacement method.
- Determination of Specific Gravity of soil by pycnometer.
Unit 3: Classification of Soil
- Classification of soil as per grain size by IS method. Basic criteria of classification of soils.
- Difference between coarse grained and fine grained soil on the basis of their size and engineering properties. Mechanical Analysis of coarse grained soil. Sedimentation analysis of fine grained soil.
- Particle size distribution curve. Nature of various grading Curves. Coefficients of uniformity and curvature.
- Classification of soil on the basis of plasticity. Atterberg's limits of consistency: Liquid limit, plastic limit and shrinkage limit. Plasticity index, Liquidity Index and Consistency Index.
- Determination of Liquid limit, Plastic limit and Shrinkage limit as per IS.
Unit 4: Permeability and Seepage
- Definition of permeability, permeable and impermeable soil, Darcy's law of permeability.
- Factors affecting the permeability of soil. Coefficient of permeability, Difference between flow through pipe and flow through soil.
- Laboratory Methods to determine Coefficient of Permeability- Constant Head Method and Falling Head method.
- Field methods to determine Coefficient of Permeability: Pumping-out tests and Pumping-in tests.
- Definition of Seepage and seepage pressure. Quick sand condition. Types of flow net. Characteristics and application of flow net.
Unit 5: Compaction and Stabilization of Soil
- Concept of compaction and its effect on various soil properties like density, permeability, shear strength & bearing capacity.
- Factors affecting compaction like water content, types of soil, nature of soil, method of compaction, admixtures.
- Optimum moisture content (O.M.C) and maximum dry density (M.D.D.) by IS standard compaction test- Light and Heavy compaction test( Proctor Test). Standard compaction curves.
- Method of field compaction. Various compaction equipment, role of O.M.C. in field.
- Concept and requirements of soil stabilization. Different methods of soil stabilization-Mechanical soil stabilization and Chemical soil stabilization (Use of cement, lime, fly ash, bitumen ). Use of Geo-Synthetic as a stabilizing material.
- Necessity of site investigation and sub soil exploration. Types and purpose of exploration. Basic field identification test of soil.
Unit 6: Shear Strength of Soil
- Cohesion, Angle of internal friction, shear strength.
- Coulomb's law for shear strength.
- Different methods to find shear strength of soil in the laboratory. Procedure to find shear strength using Box shear test.
- Types of soil- C-soil, ø-soil and C-ø soil. Mohr's circle method to find shear envelope and shear strength parameters.
Unit 7: Bearing capacity of Soil and Earth Pressure
- Concept of bearing capacity. Types of Bearing capacity- Ultimate bearing capacity, Safe bearing capacity, Net bearing capacity and Allowable bearing pressure. Influence of water table on bearing capacity.
- I.S. method to determine bearing capacity of soils. Different theoretical methods to determine bearing capacity of soils. Introduction to Terzaghi's analysis. Assumptions and limitations of Terzaghi's theory. Different field methods for determination of bearing capacity - Plate load Test and Standard Penetration Test.
- Different types of footings. Types of shear failure of footings. Methods to improve bearing capacity of soils.
- Define Earth Pressure. Active and passive earth pressure for no surcharge condition. Rankine's formula to determine coefficient of earth pressure.
- Liquefaction: Definition, Causes, Effect and Remedy of Liquefaction.
About this course
After learning Mechanics of rigid bodies in 2nd semester, this subject "Soil Engineering" is introduced in 3rd semester, as it deals with the natural material "Soil" whose behaviour is somewhat intermediate between solids and fluids. Soil Engineering involves study of Soil, its behaviour and application as an engineering material. Design of foundation of building, dams, towers, embankments, roads, railways, retaining wall, bridges is mainly governed by characteristics and behaviour of Soil, hence this subject is very important for Civil engineering students.