Question

A load of 1863 kN is carried on a 1.5 by 2 m rectangular foundation at a shallow depth in a soil mass. Determine the vertical stress at the centre of the footing 4 m below
the footing underside assuming: (a) the load is uniformly distributed over the pad and, (b) the load acts as a point load at the centre of the foundation.

Answer 1

a) Given size = 1.5 x 2 m2 Uniform pressure 1863 =621KN / m2 2x1.5 The area must be considered as four quarters n=B/z &m=L/: n=1.5/4 m=2/4 n=0.375 m=0.5

0.26 noo 0.2. na 2.0 0.224 NELO 0.20 n=0.8 0.18 0.6 n06 'N 0.12 nr0.5 0.121 n=0.4 0.10 0:0. 0.08) In 20.2 0.06 0.04 n.0.1 0.021 0.00 0.1 02 0.5 20 100 From the fig, I, = 0.06 o = 491, = 4x 621 0.06 149.04 KN / m2

b) From Boussinesq theory at z o. -1, AT (r/z)=0 I, = 3 21 1.0. 1863 42 3 20 0. = 55.594 kN/m2

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