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Seat No.: Enrolment
GUJARAT TECHNOLOGICAL UNIVERSITY
PDDC SEMESTER-IV EXAMINATION WINTER 2018
Subject Code:X40603 Date: 28/11/2018
Subject Name: Soil Engineering
Time: 02:30 PM TO 05:00 PM Total Marks: 70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
Q.1

Explain briefly factors affecting compaction of soil.
07

Describe direct shear test with its advantages and dis advantages.
07
Q.2

Explain in detail UU, CU and CD type of shear test.
07

A laboratory compaction test on soil having specific gravity equal to 2.60 gave a maximum dry density of 1.80 g/cm3 and a water content of 18 Determine the degree of saturation, air content and percentage air voids at the maximum dry density. What would be maximum dry density corresponding to zero air voids at the optimum water content.
07
OR

A cylindrical specimen of saturated clay, 4 cm in diameter and 9 cm in overall length is tested in an unconfined compression test. The specimen has cone ends and its length between apices of cones is 8 cm. Find the unconfined compressive strength of clay, if the specimen fails under an axial load of 46.5 N. The change in length of specimen at failure is 1 cm.
07
Q.3

Differentiate between compaction and consolidation.
07

In a drained consolidated triaxial test, a specimen of clay fails at a cell pressure
of 50 kN/m2. The effective shear parameters are C 15 kN/m2 and 21degree Calculate the deviator stress.
07
OR
Q.3

Explain Earth pressure at rest and also define active and passive earth pressure.
07

A counterfort wall of 12 m height retains non-cohesive backfill. The void ratio and angle of internal friction of the backfill respectively are 0.8 and in the loose state and they are 0.5 and in the dense state. Calculate and compare active and passive earth pressure in the both states. Take the specific gravity of soil grains as 2.7.
07
Q.4

Differentiate between Boussinesq's theory and Westergaard's theory.
07

A concentrated load of 110 kN acts on the surface of a homogeneous soil mass of large extent. Find the stress intensity at a depth of 5m and
Directly under the load, and
At a horizontal distance of 6m. Use Boussinesq's equation.
07
OR
Q.4

Explain friction circle method of stability analysis.
07

Differentiate between Finite and Infinite slope. Explain the method of checking the stability of a finite slope by Swedish method of Slices for a Cohesive frictional soil.
07
Q.5

Explain New mark's influence chart.
07
2

Describe briefly limitations and differences of Rankine's and Coulomb's earth pressure theory.
07
OR
Q.5

Explain mechanism of consolidation by spring analogy.
07

A consolidation test performed on 2cm thick clay gives 50% consolidation in 5 minutes. How long will a 3.7m thick layer in field take to consolidate to the same value if drainage condition in both cases is double drainage?
07