E E4809 Pages: 2

6 9) Explain effective stress principle. (5) b) A saturated specimen is permanently under
water. Its water content is 50% and (10)

G=2.72. What is the effective stress at 8 m below the clay surface? How many

meters of clay must be removed by dredging to reduce the intergranular

pressure at that point by 25 kPa. The water levels remain unchanged.

PARTC

Answer any two full questions, each carries 20 marks

7 9०) What are the different types of finite slopes? Give measures for improving the (10)
stability of $10005... 0) Explain Friction circle method of slope stability analysis. (10)

8 9) A 20 m thick isotropic clay stratum overlies an impervious rock. The (10) coefficient of
consolidation 18 5x10°mm/7/s. Find the time required for 50% and 90% consolidation. The time
factor for 50% consolidation is 0.2 and for 90% consolidation is 0.85

b) At a building site soil consist of dense sand upto a depth of 3m, clay from 3m

(10)

to 6m depth and stiff impervious rock below 6m depth. The water table is at 1m

below the present ground level. Density of sand is 19.5 kKN/m? above water table

and 20 kN/m? below it. The natural water content of clay was observed as 60%,

and specific gravity is 2.65. Its liquid limit was 75%. Estimate the probable

settlement if the ground level is raised by a 2 m thick fill of dense sand of density

19 तषि).

9 ‏رو‎ Acohesive soil yields a maximum dry density of 18kN/m3 at an optimum (10) moisture
content of 16% during a standard proctor test. If the value of G is 2.65, what is the degree of
saturation? What is the maximum dry density it can be further compacted to?

0) A5m deep cut is made in a soil having Cu=15 kN/m? and =10°, if the slope (10)
is 1:1 what is the factor of safety with respect to cohesion? If the slope is changed
to 1:1.5 H, what will be the change in factor of safety with respect to cohesion?
The unit weight of soil is 18 kN/m’. The stability numbers for =10° are 5
follows
Slope angle

Stability 0.108 0.075 0.023
number

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