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Seat No.: Enrolment
GUJARAT TECHNOLOGICAL UNIVERSITY
ME SEMESTER-1 EXAMINATION WINTER 2018
Subject Code: 3714307 Date: 01/01/2019
Subject Name: Advanced Soil Mechanics
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 mark
Q.1

Classify the shear tests based on drainage conditions. Explain how the pore pressure variation and volume change take place during the tests.
07

Enlist assumptions and Derive equation for Terzaghi's theory of one dimensional consolidation.
07
Q.2

Differentiate critically between Rankine and Coulomb's theories of earth pressure.
Explain briefly determination of Pre- consolidation pressure.
07

A thin layer of silt exists at a depth of 20 meter below the surface of the ground. The soil above this level has an average dry density of 15.3 kN/m3 and an average water content of 34 . The water table is almost at the surface. Test on the undisturbed sample of the silt indicates the following values
Cu 45 kN/m2 18 36 kN/m2, 27 . Estimate the shearing
resistance of the silt on horizontal plane
When the shear stress builds up rapidly
When the shear stress builds up very slowly.
07
OR

A retaining wall 6 meter high with a smooth vertical back, retains a clay backfill with 18 kN/m2 and 18 kN/m3 . Calculate the total
active thrust on the wall assuming that tension cracks may develop to the full theoretical depth.
07
Q.3

Write and explain the Boussinesq's equation for stress distribution in soil for
a point load and Line load
07

A rectangular footing 3.0 m x 2.0 m carries a uniformly distributed load of 300 kN/m2. Find intensity of vertical pressure at a depth of 4.5 m below the center of the footing.
07
OR
Q.3

A recently completed fill was 10 meter thick and its initial average void ratio was 1.0. The fill was loaded on the surface by constructing an embankment covering a large area of fill. Some months after the embankment was constructed, measurements of the fill indicated an average void ratio of 0.8 . Estimate the compression of the fill.
07

A soil sample has a compression index of 0.3. If the void ratio e at a stress of 14 m2 is 0.5 Compute the void ratio if the stress s increased to 20 m2, and the settlement of soil stratum 4 meter thick.
07
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Q.4

Write detail note on 'stress path'.
07

A clay layer, whose total settlement under a given loading is expected to be 12 cm settles 3 cm at the end of one month after the application of load increment. How many months will be required to reach a settlement of 6 cm? How much settlement will occur in 10 months? Assume the layer to have double drainage.
07
OR
Q.4

Write note on properties of a flow net in detail.
07

Calculate the coefficient of permeability of a soil sample, 7 cm height and 60 cm2 in cross sectional area, if quantity of water equal to 500 ml passed down in 10 minutes under an effective constant head of 40 cm. On oven drying the test specimen weighs 495 grams. Taking the specific gravity of soil solids as 2.65, calculate the seepage velocity of water during the test.
07
Q.5

What is the basis of the construction of the Newmark's influence chart? How is it used?
07

Enlist applications of flow net and explain any two applications in detail.
07
OR
Q.5

Explain clearly Rebhann's graphical construction method to evaluate the earth pressure on a retaining wall. What are the advantages disadvantages of Culmann's graphical method as compared to Rebhann's graphical method?
07

An embankment 5 meter high, is made up of soil whose effective stress parameters are 50kN/m2 and and 16.2 kN/m3. The pore pressure parameters as found from the Triaxial test are A 0.40 and B 0.92. Find the shear strength of the soil at the base of the embankment just after the fill has been raised from 5 meter to 9 meter . Assume that the dissipation of pore pressure during this stage of construction is negligible and that the lateral pressure at any point is one half of the vertical pressure.
07