Question

Find the vertical pressure at depth 5m for a uniformly loaded circular area of 80 kN/m^2 load and radius of 5m.

(a) 51.72 kN/m^2

(b) 54.12 kN/m^2

(c) 78.325 kN/m^2

(d) 12.24 kN/m^2

I got this question during an online interview.

This interesting question is from Stress Distribution in division Stress Distribution of Geotechnical Engineering I

Answer 1

The correct option is (a) 51.72 kN/m^2

Explanation: Given,

uniformly loaded circular area of radius a=5m

depth z=5m

load q=80 kN/m^2

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

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

∴  \(σ_z=80\left[1-\left[\frac{1}{1+(\frac{5}{5})^2}\right]^\frac{3}{2}\right] \)

∴  σz=51.72 kN/m^2.