This module will provide the learner with the principles of soil mechanics and how to use them for the design of agricultural machines and the analysis of field data.
- Soil classification:
Soil properties (moisture content, porosity, void ratio), Granulometry curve, Liquid limit, plastic limit, shrinkage limit, plastic index, clay activity index, plasticity chart, determination of liquid limit by Casagrande's spoon, determination of plastic limit.
- Soil elasticity:
Young's modulus, Poisson's coefficient, shear modulus.
- Mohr's circle:
Principal directions.
- Shear strength:
Coulomb failure line, soil friction angle, cohesion, Mohr-Coulomb failure criteria.
- Soil strains:
Consolidation, compaction.
- Lateral earth pressure:
Active, passive and at rest conditions according to Raking and Coulomb theories.
- Foundations:
Terzaghi's formula for the calculation of soil bearing capacity.
- Performance characterization of tractors:
Drawbar pull and power, traction efficiency (slip efficiency, motion resistance), tractor mobility, soil trafficability.
- Soil cutting and tillage:
Calculation of cutting forces, volume of soil cut, soil loosening.
- Laboratory soil shear testing:
Triaxial test (CD, CU, UU), direct shear test.
This module involves both development of competence in both theory and practical skills; Practical work will be carried out in our specialized workshop; Lectures will be delivered using Prepared Handouts, White Board, Overheads, PowerPoint Presentations; Final examination will be given to assess learning.
Students who do not possess a passing grade or the required attendance at the semesters end will be required to sit a computer based exam. In the event a student fails module due to not meeting 80% attendance at practical/workshop sessions outside of extenuating circumstances, then repeat attend is required at next available offering of the module.