Geotechnical Engg (CE-701) - Important Questions

Draw the soil phase diagram and derive from fundamentals the relationship e Sr = w G.

The moist unit weight of a soil is 16.50 kN/m3. Given water content 15% and specific gravity of soil solids 2.70, find dry unit weight, porosity, degree of saturation and mass of water to be added per cubic metre for full saturation.

The water table in a deposit of uniform sand is located at 2 m below the ground surface. Assuming the soil above the water table is saturated by capillarity, determine the total stress, pore water pressure and effective stress at a depth of 5 m below the ground surface. Take G = 2.65, e = 0.70.

Define quick sand condition and derive the expression for critical hydraulic gradient.

Explain flow nets, their characteristics and uses in seepage analysis.

A soil strata consists of 3 layers of thickness 1 m, 1.5 m and 1.9 m having coefficients of permeability 2.3 x 10^-3 cm/s, 1.85 x 10^-3 cm/s and 3.5 x 10^-4 cm/s respectively. Estimate the average coefficient of permeability parallel and normal to the direction of flow.

Two point loads P = 100 kN and Q = 80 kN act on the ground surface 8 m apart. Using Boussinesq's theory with superposition, calculate the vertical stress increase at a depth of 6 m directly below P and at a point midway between P and Q at 5 m depth.

Compare and contrast Boussinesq's and Westergaard's theories for stress distribution in soils.

What is field compaction and what are the different methods of field compaction?

State and discuss the assumptions of Terzaghi's theory of one-dimensional consolidation and their validity.

There is a layer of soft clay 4 m thick under a newly constructed building. The overburden pressure over the centre of the clay layer is 300 kN/m2. Compute the consolidation settlement if there is an increase in pressure of 120 kN/m2 due to construction. Take Cc = 0.45, e0 = 1.10.

Explain any one method to compute the coefficient of consolidation - square root time or logarithm of time fitting method.

Explain the types of shear tests based on drainage conditions (UU, CU, CD) and the significance of each drainage condition.

What are the methods of soil stabilization? Explain functions and applications of geosynthetics in detail.

A partially saturated clay weighs 113.4 gm in its natural state and 93.4 gm in its dry state. If specific gravity is 2.65 and volume of sample is 60 cc, find void ratio, porosity, degree of saturation, bulk unit weight, dry unit weight and saturated unit weight.

Describe the direct shear test. What are its merits and demerits compared to the triaxial test?