Question

The value of vertical stress due to point load of 60 kN at a radial distance 2 m from the axis of load at a depth of 5 m is in $kN/m^2$. (Answer correct upto two decimal place). [Use Westergaard equation]

• A. 1.5
• B. 2.5
• C. 0.5
• D. 3.5

Answer 1

The correct option is C 0.5

${\sigma }_z=\frac{Q}{\pi z^2}{\left[\frac{1}{1+2{\left(\frac{r}{z}\right)}^2}\right]}^{3/2}\left(\text{Westerguard equation}\right)$

Given, Q = 60 kN, r = 2 m, z = 5 m

${\sigma }_z=\frac{60}{\pi \times 5^2}{\left[\frac{1}{1+2{\left(\frac{2}{5}\right)}^2}\right]}^{3/2}\left(\text{Westerguard equation}\right)$

$=0.504kN/m^2\simeq 0.50kN/m^2$