GATE Civil Engineering (CE) 2018 Shift 2 Solved Paper

Question : 39 of 65

Marks: +1, -0

A group of nine piles in a

3 × 3

square pattern is embedded in a soil strata comprising dense sand underlying recently filled clay layer, as shown in the figure. The perimeter of an individual pile is

126 {cm}

. The size of pile group is

240 {cm} × 240 {cm}

. The recently filled clay has undrained shear strength of

15 {kPa}

and unit weight of

16 {kN} {/} {m}^{3}

The negative frictional load (in, kN, up to two decimal places) acting on the pile group is

Your Answer:

Validate

Solution:

pile group
Negative skin friction for group.

=α \ov{c}(4 B L)+

weight of soil in negative zone.

\;\; =α \ov{c}(4 B L)+γ[\;\text " Area "\; × \;\text " length "\;]

\;\; =1 × 15[4 × 2.4 × 2]+16[2.4^{2} × 2]

\;\; =472.32 {kN} {/} {m}^{2}

Negative skin friction in individual action.

\;\; = {n}[α \ov{c}(\;\text " perimeter "\; × I)]

\;\; =9[0.5 × 15 × 1.26 × 2]=170.1 {kN} {/} {m}^{2}

Negative skin friction is maximum of above (two)

Q_{n f}=472.32 {kN}{/} {m}^{2}

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