Register Number
(Established under section 3 of UGC Act,1956)
Course & Branch :B.E - CIVIL
Title of the Paper :Soil Mechanics – I Max. Marks:80
Sub. Code :620503 (2007-08-09) Time : 3 Hours
Date :07/11/2012 Session :FN
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PART - A (10 x 2 = 20)
Answer ALL the Questions
1. A compacted sample of soil with a bulk unit weight of 19.62 kN/m 3 has a water content of 15%. What are its dry density, degree of saturation and air content? Assume G=2.65.
2. What is porosity of a given soil sample?
3. For a given soil, the coefficient of permeability increases with an increase in void ratio. Why?
4.
State Darcy’s Law.
5. Find the intensity of vertical pressure at point 5m directly below the vertical load of 25 kN.
6. What are the field compaction methods?
7. Define normally consolidated and over consolidated clays.
8. Define compression Index?
9. Write down the coulomb’s expression for shear strength?
10. What are the types of failure?

PART – B (5 x 12 = 60)
Answer All the Questions
11. 1 cum of wet soil weights 20 kN. Its dry weight is 18 kN.
Specific gravity of solids is 2.67. Determine the water content, porosity, void ratio and degree of saturation. Draw a phase diagram.
(or)
12. The following index properties were determined for two soils x and y.
Property
Liquid limit
Plastic limit
X
62%
26%
Natural water content 38%
Specific gravity of soil 2.72
Degree of saturation 100%
Y
34%
19%
25%
2.67
100%
Which of these soils are:
(a) Contains more clay particles
(b) Has a greater wet density
(c) Has a greater dry density
(d) Has a greater void ratio. Give reasons for your answers.
13. What will be the ratio of average permeability in horizontal direction to that in the vertical direction for a soil deposit consist of three horizontal layers, if the thickness and permeability of second layer of twice of those of first and those of the third layer twice those of second?
(or)
14. A layer of fine sand 3m in thickness rests on a bed of soft clay and the water table is at a depth of 2m below the ground level.
The porosity of sand is 50% and degree of saturation of the sand above the water table is 60% and the specific gravity is 2.7
The specific gravity of solids and water content of the clay are
2.7and 40% respectively. Draw the variation of effective stress upto a depth of 7m from the ground level.

15. Using boussinesq’s analysis, find the maximum vertical stress on a vertical line that is at a radial distance of 5m from the line of action of a concentrated load of 100 kN. Derive the equation used, if any.
(or)
16. What are the field compaction methods and explain?
17. Explain how coefficient of consolidation is determined based on
√t vs dial reading Method.
(or)
18. Explain the meaning of the terms consolidation and settlement and the soil properties that affect them. Explain what is meant by a normally consolidated and an over consolidated clay stratum.
Sketch curves showing the variation of void ratio with effective stress increase in each case.
19. Derive the equation for major principal stress using mohr-columb criteria.
(or)
20. A slip surface with a radius of 22 m in a slope with the height of
14m and an angle of inclination of 45 0 . If Ø m
= 15 0 , γ= 18 kN/m 3 and c = 40 kN/m 2 , determine the factor of safety with respect to cohesion using the friction circle method. The weight of the soil wedge is 1500 kN and it acts at a horizontal distance of 10.3 from A.