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D1069 Pages: 2

shear stress.

State any 4 merits of triaxial test over direct shear test.

A permeameter of 80mm diameter contains a 2-layered soil sample of length
300mm (200mm thick soil having k=4x10°° mm/sec. underlain by 100mm thick
soil with k=4x10°7 mm/sec.) If a falling head permeability test is conducted on
this soil with a standpipe of diameter 15mm., what would be the time taken the
time taken for the head to fall from 500mm to 100mm?

PART C
Answer any two full questions, each carries 20 marks
The following observations were recorded in a consolidation test on a fully

saturated sample. Initial height of sample= 20mm; diameter of sample=60mm;

Applied pressure | 0 25 50 [100 | 200 | 400 | 800
(kPa)

Height of soil sample | 20 17.5 17.1 | 16.5 15 13.5 12.0
(mm)

Dry weight of soil sample=76.34gms.; G=2.7; Draw e-log p graph and estimate
compression index.

An embankment is constructed at dry density-OMC condition (20kN/m? and 9%).
Borrow area soil has: G=2.5. Determine degree of saturation and percentage air
voids of the compacted soil. Also determine the theoretical maximum dry density
to which the sample can be compacted. Assume density of water =10kN/m?.
What is meant by factor of safety with respect to cohesion. When does it become
equal to factor of safety with respect to shear strength?

How can the pre-consolidation pressure on clay be estimated?

What are the forces considered in friction circle method of slope analysis?

Suggest any 4 methods for improving the stability of a slope.

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