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02000CE208052002

table is 40% saturated. The void ratio of sand layer is 0.6 with a specific gravity
of 2.65. The clay layer has a water content of 45% with a specific gravity of
2.70. Draw the Total, neutral and effective stress diagram up to a depth of 8m.
Neglect capillary flow.

What are the advantages of triaxial test over direct shear test?

A vane 108mm long and 72mm in diameter was pressed into a soft clay at the
bottom of the bore hole. Torque was applied and its value at failure was 45N.m.
Find the shear strength of the clay on the horizontal plane. If the top of the vane
is flush with the surface of the soft clay, find the torque that is required to be
applied for failure

In a drained triaxial test on a dense sand the cell pressure was 150kPa and the
deviator stress to cause failure was 540kPa. Calculate the angle of internal
friction. Also find the angle made by the failure plane with respect to the major
principal plane.

A sample in a variable head permeameter is 100mm in diameter and 120mm
high. The permeability of the sample estimated to be 10°mm/s. If it is desired
that the head in the stand pipe should fall from 250mm to 100mm in 180s,
determine the size of the stand pipe to be used.

The following results were obtained when a loose silty sand was tested in a

direct shear test.

Maximum Shearing Stress (kN/m*) 95 160 237

Determine:
a) the shear strength parameters for the soil
b) the magnitude of principal stresses and the orientation of principal planes.
Write the laboratory tests to determine the shear strength parameters of soil.
PART C

Answer any two full questions, each carries 20 marks
What are the assmptons in Terzaghi's one dimensional consolidation theory
In a laboratory consolidometer test on a 20mm thick sample of saturated clay
taken from a site, 50% of the consolidation was reached in 10111110105. Estimate
the time required for the clay layer of 5m thickness at the site for 50%
compression if the bottom is impervious. Assume that the laboratory sample and

the clay sample at the site are both subject to the same increase in stress. How

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