Syllabus - Soil Mechanics (AN402)

Agriculture Engineering

Soil Mechanics (AN402)

IV-Semester

Unit I

Nature of soil and functional relationships

Formation of soils - Soil type - 3 phase system -void ratio - specific gravity - dry density - porosity - water content - saturated unit weight -submerged unit weight - degree of saturation – Soil Structure: single grained, honey combed,flocculated and dispersed structure and their effects on the basic soil properties.

Laboratory and field identification of soils

Determination of water content by oven drying– Specific gravity using pycnometer and specific gravity bottle - Grain size analysis by sieve analysis, hydrometer analysis and pipette analysis - Atterberg limits and indices – Visualidentification by simple field tests – Field density by core cutter, sand replacement and wax coating methods

Classification of soils

Necessity - Principles of classification - I.S. classification – Plasticity charts – Group index.

Unit II

Soil water

Modes of occurrence – adsorbed and capillary water types - Total stress -Effective stress – Pore pressure - Pressure diagrams.

Permeability

Definition - Darcy’s law - Factors affecting permeability – Laboratory determination - Stratified soils: average permeability.

Shear Strength

Definition - Mohr’s strength and stress circles - origin of planes - Mohr’s envelope - Mohr- Coulomb strength theory –Direct shear test – introduction to triaxial shear test- Measurement of pore pressure -Total and effective stressstrength parameters - UCC test - Vane shear tests - Choice of test conditions for fieldproblems.

Unit III

Consolidation

Definition –Spring analogy for primary consolidation - Terzaghi’s theory of one dimensional consolidation – Concepts of coefficient of compressibility - Coefficient ofvolume change and compression index – Laboratory consolidation test - e-log p curves – pre-consolidation pressure - Time rate of consolidation - difference between consolidation andcompaction.

Compaction

Definition and objectives of compaction – Standard and Modified Proctor tests- Concept of OMC and maximum dry density - Zero air voids line - Factors influencingcompaction - Effect of compaction on soil properties - Field compaction methods – Proctorneedle for field control.

Unit IV

Earth pressure

Earth pressure at rest - Active and passive earth pressure for cohesionlessand cohesive soils - Rankine’s and Coulomb’s theories - Point of application of earth pressure for cases of with and without surcharge in cohesionless and cohesive soils - Culmann’s and Rebhan’s graphical construction for active earth pressure-

Stability of slopes

Slope failure, base failure and toe failure - Swedish circle method – Φ = 0analysis and c = 0 analysis - Friction circle method - Taylor’s stability number –Stabilitycharts.

Course Objective

Describe the fundamentals of soil mechanics and to equip the students to understand the properties and behavior of soil for the design of foundations, earth and earth retaining structures.

Course Outcome

Student understand the fundamentals of soil mechanics and able to understand the basic, index and engineering properties of soil and also understand the properties and behavior of soil for the design of foundations, earth and earth retaining structures.

Practicals

  • Determination of water content of soil

  • Determination of specific gravity of soil

  • Determination of field density of soil by core cutter method

  • Determination of field density by sand replacement method

  • Grain size analysis by sieving (Dry sieve analysis)

  • Grain size analysis by hydrometer method

  • Determination of liquid limit by Casagrande’s method

  • Determination of liquid limit by cone penetrometer and plastic limit

  • Determination of shrinkage limit

  • Determination of permeability by constant head method

  • Determination of permeability by variable head method

  • Determination of compaction properties by standard proctor test

  • Determination of shear parameters by Direct shear test

  • Determination of unconfined compressive strength of soil

  • Determination of shear parameters by Tri-axial test

  • Determination of consolidation properties of soils.

  • Determination of consolidation properties of soils.

Reference Books

  • Arora K. R., Soil Mechanics & Foundation Engineering, Standard Publications, 1987. Murthy V. N. S., Soil Mechanics & Foundation Engineering, DhanpatRai, 1996 Punmia B. C., Soil Mechanics & Foundations, Laxmi Publications, 1988

  • Cudoto, Geotechnical Engineering Principles and Practices, Pearson Education, 2007 Gopal Ranjan & Rao A. S. R., Basic & Applied Soil Mechanics, New Age International Publishers, 2000

  • Khan I.H., Text Book of Geotechnical Engineering, Prentice Hall of India

  • Terzaghi K. & Peck R.B., Soil Mechanics in Engineering Practice, John Wiley & Sons, US, 1967.

  • Venkatramiah C., Geotechnical Engineering, New Age International Publishers, 2006