Question

Geotechnical / Soil engineering.

For points located at 10 m below the center and corner of a 30 m x 50 m raft foundation, estimate the addition vertical pressure (A) due to having a net foundation stress of 400 kPa using: 1- The influence coefficient method. 2- The approximate method. In addition, estimate (using the two methods) the vertical stress (A) for a point located at a the same depth but 6 m away from the raft corner (along the raft short side). Comment on your results

Answer 1

Given Data: son 3om zlom GA & sor= 400k pa Net Foundation 2 = sovx Area Louds = 400 × (30x50) - 600 000 kn @ Influence crefficient to find: (1) Pressure at untur & corner by to increase method. b Apprainal Influence 4t Cosme _ 2 10 T = 0.384 400kPa coefficent method: m= = 50 - $; n = § - 30 = 36 For m=5 ,n=3 I = 162 = I. q 2 = 0.38 4 x 400 = 153.6 kN/m2 - At corne) Ans antre i 2 I m= 1 = 25 = 2.5 ; n = B = 15 = 1.5 Sekoloz To Foe m= 2.5, n=1.5 = I= 0.226 O2 = 4( 0.226 X 4002 At unter – 361.6 kN/m2 An. At 6 m away from roft: Ford m=56 = 5.6 ; n = 30 = 3 I= 0.387 z = 0.387 X 400 = 154.8 kN/me. For 6 = m =30=3 ; n = b = 0.6 10 som © 30m tom 10 10 t = 0.96 z = 0.936 x 400 = 3744 kN/m² Net sy = 2 621 = 374.4 - 154 8 = 219.6 kn/m² Ans.
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