(SEM V) THEORY EXAMINATION 2020-21 GEOTECHNICAL ENGINEERING

SECTION A (Any 2 Questions Explained Briefly)
 

Explain the process of soil formation and differentiate between residual and transported soil.
Soil formation is the process by which rocks break down into smaller particles due to physical, chemical, and biological weathering. Residual soil is formed at the place where the parent rock disintegrates and remains at the same location, while transported soil is carried away from its original place by agents like water, wind, ice, or gravity and deposited elsewhere.
 

Define total stress, neutral stress and effective stress.
Total stress is the stress exerted by the weight of soil and water above a point. Neutral stress, also called pore water pressure, is the pressure exerted by water present in the soil pores. Effective stress is the stress carried by soil particles and is responsible for soil strength and deformation.
 

SECTION B (Any 2 Questions Explained)
 

Determine the neutral and effective stress below ground surface (conceptual explanation).
Neutral stress depends on the depth below the water table and is calculated using unit weight of water. Effective stress is obtained by subtracting neutral stress from total stress. This concept is important because soil strength and settlement depend mainly on effective stress rather than total stress.
 

Differentiate critically between Rankine and Coulomb earth pressure theories.
Rankine’s theory assumes a smooth vertical wall and neglects wall friction, making it simpler to apply. Coulomb’s theory considers wall friction, wall inclination, and backfill slope, making it more realistic but complex. Coulomb’s theory generally gives more accurate results for practical retaining wall problems.
 

SECTION C (Any 2 Questions Explained)
 

Explain the importance of classification of soils.
Soil classification helps engineers identify soil behavior, strength, and suitability for construction. It provides a systematic way to group soils with similar properties, which helps in foundation design, pavement construction, and soil improvement methods. Proper classification reduces uncertainty in geotechnical design.
 

Explain quick sand condition and critical hydraulic gradient.
Quick sand condition occurs when upward seepage force equals the submerged weight of soil particles, causing the soil to lose strength and behave like a liquid. The critical hydraulic gradient is the hydraulic gradient at which this condition occurs and is important in the design of foundations and hydraulic structures.
 

Most Questions in This PDF Are Related To
 

Most questions in the Geotechnical Engineering (KCE-501) paper are related to soil formation and classification, soil properties, permeability and seepage, effective stress concepts, consolidation, shear strength of soils, earth pressure theories, retaining walls, and foundation-related problems. The paper mainly focuses on soil mechanics fundamentals and their application in civil engineering design.