Question

A footing 2 m $\times$ 1 m exerts a uniform pressure of 150 kN/$m^2$ on the soil. Assuming a load disperesion of 2 vertical to 1 horizantal, the average vertical stress (kN/$m^2$) at 1.0 m below the footing is

• A. 50
• B. 75
• C. 80
• D. 100

Answer 1

The correct option is A 50

Size of footing = 2 m $\times$ 1 m
Pressure = 150 kN/$m^2$
Load = 150 $\times$ 2 $\times$ 1
= 300 kN
Load dispersion is 2V : 1H
Size of footing at 1 m depth
$=(2+1)\times (1+1)$
$=3m\times 2m$
Average vertical stress

$=\frac{Load}{Area}=\frac{300}{3\times 2}$

$=50kN/m^2$