Download Sathyabama University B.E May 2011Soil

Register Number
SATHYABAMA UNIVERSITY
(Established under section 3 of UGC Act,1956)
Course & Branch :B.E - CIVIL
Title of the Paper :Soil Mechanics – I
Sub. Code :620503
Date :02/05/2011
Max. Marks :80
Time : 3 Hours
Session :AN
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1.
PART - A
Answer ALL the Questions
Define: Porosity of the soil.
(10 x 2 = 20)
2.
Write the classifications of soil as per Indian Standard.
3.
What are the factors affecting permeability of soil?
4.
State Darcy’s law.
5.
What do you mean by Compaction?
6.
What is the use of CBR test?
7.
How swelling differs from consolidation?
8.
What are the various methods available to determine the
coefficient of consolidation?
9.
List any 2 methods to measure the shear strength of the soil in the
laboratory.
10. A long natural slope of sandy soil ( = 25) is inclined at 10 to
the horizontal. The water table is at the surface and the seepage is
parallel to the slope. If the unit weight of the soil is 19.5 kN/m3,
determine the factor of safety of the slope.
PART – B
Answer All the Questions
(5 x 12 = 60)
11. The Atterberg limits of a clay soil are: liquid limit 52%, plastic
limit 30% and shrinkage limit 18%. If the specimen of this soil
shrinks from a volume of 39.5 cm3 at the liquid limit to a volume
of 24.2cm3 at the shrinkage limit, calculate the true specific
gravity.
(or)
12. Explain with a neat sketch how you will determine the liquid
limit of soil in the laboratory.
13. Calculate the coefficient of permeability of soil sample, 6 cm in
height and 50 cm2 in cross sectional area, if a quantity of water
equal to 430 ml passed down in 10 minutes, under an effective
constant head of 40 cm. On over-drying, the test specimen has
mass of 498 g. Taking the specific gravity of soil solids as 2.65,
calculate the seepage velocity of water during the test.
(or)
14. For the soil profile shown in fig.1, determine the effective and
neutral stresses at AA and BB. Take sat = 2t/m3 and b = 1.8t/m3.
What will be the effective stress if the water table rises to the
surface CC?. Suppose the water table remains at BB but the soil
upto 0.5m above the water table is saturated by capillary action,
what will be the effective pressures at AA and BB?
15. A water tank is supported by a ring foundation having outer
diameter of 10m and inner diameter of 7.5m. The ring foundation
transmits uniform load intensity of 160 kN/m2. Compute the
vertical stress induced at a depth of 4m, below the centre of ring
foundation using (a) Boussinesq analysis (b) Westergaard’s
analysis taking  = 0.
(or)
16. Explain the Standard Procor Test of Compaction in detail with a
neat sketch.
17. Explain the procedure for determination of coefficient of
consolidation by any one method.
(or)
18. In a laboratory test, a sample of clay 24mm thick consolidated
50% in 20 minutes with double drainage. How much time will it
take for a layer of the same clay 6mm thick to consolidate (i)
50% (ii) 30%?. If the clay layer in the field has single drainage,
determine the time for it to consolidate (i) 50% (ii) 30%.
19. Explain with a neat sketch, the Vane Shear Test to determine the
undrained shear strength of cohesive soils.
(or)
20. Discuss the friction circle method of soil slope stability analysis.