Question

When the ratio of r/z equals to 0.5, the Boussinesq influence factor is ________ of the maximum.

(a) 23%

(b) 57%

(c) 17.7%

(d) 1.8%

I got this question in unit test.

My enquiry is from Stress Distribution in section Stress Distribution of Geotechnical Engineering I

Answer 1

Correct option is (b) 57%

To elaborate: Given,

r/z=0.5

The maximum KB is given by,

r/z=0, therefore KB=0.4775

for r/z=0.5, KB=0.2733

∴ the Boussinesq influence factor is 0.2733/0.4775*100=57% of the maximum.