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E1152 Pages: 2

PART C
Answer any two full questions, each carries20 marks.

An RCC pile (of 500mmX500mm size and length 6m) is installed in a granular
soil having unit weight =17kN/m’, coefficient of earth pressure = 1.5; angle of
wall friction=22 °. Determine the ultimate skin friction load that can be carried
by pile.

State any two merits of auger boring method of soil exploration compared to
wash boring. Mention the soil types for which the auger boring method is
applicable. Mention the different types of augers and draw a neat sketch of any
one.

A 3X3 friction pile group, each pile having a length of 10m and diameter of 0.4m
is installed in a homogeneous clay layer having undrained shear strength of
50kPa. Take adhesion factor as 0.75. Estimate the ultimate load on the pile
group. c/c spacing of piles = 0.9m

What is meant by free vibration? Discuss any 3 methods for vibration isolation.

Explain [with a sketch] negative skin friction on pile. A circular concrete pile of
diameter 300mm and length 8m is installed in a subsoil consisting of top 2.5m of
recently filled up soil (cohesion of 25kPa). Determine the negative skin friction
on the pile. Take adhesion factor as 0.5.

What is meant by dilatancy correction? What are the soil types/soil states for
which the above correction is applied? Give the related equation for dilatency

correction.
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