Question

Find the load at depth 10m for a uniformly loaded circular area of radius 1000m. k=1. The vertical pressure σz is 80 kN/m^2.

(a) 51kN/m^2

(b) 54 kN/m^2

(c) 80 kN/m^2

(d) 12kN/m^2

I got this question in an interview for job.

Asked question is from Stress Distribution in portion Stress Distribution of Geotechnical Engineering I

Answer 1

The correct answer is (c) 80 kN/m^2

The explanation is: Given,

uniformly loaded circular area of radius a=10m

depth z=1000m

vertical pressure σz = 80 kN/m^2

The Boussinesq’s vertical pressure σz under a uniformly loaded circular area is given by,

\(σ_z=q\left[1-[\frac{1}{1+(\frac{a}{z})^2}]^\frac{3}{2}\right]\)

∴ \(80=q\left[1-[\frac{1}{1+(\frac{1000}{10})^2}]^\frac{3}{2}\right]\)

∴ q=80 kN/m^2.