Question

A plate bearing test was carried out on a subgrade using a $76cm$ diameter rigid plate.A deflection of $1.25mm$ was caused by a pressure of $0.84kg/c{m}^2$. The modulus of subgrade reaction in $kg/c{m}^3$_____

• A. 6.81

Answer 1

The correct option is A 6.81
Modulus of subgrade reaction for 76 cm dia of plate

$k_{76}=\frac{P}{\Delta }=\frac{0.84}{0.125}$

$=6.72kg/c{m}^2$

As per IRC, modulus of subgrade reaction is always reported corresponding to 75 cm dia of plate.

We know that,
$K\times a=\text{constant}$
$K_{75}\times 75=K_{76}\times 76$
$K_{75}\times 75=6.72\times 76$
$K_{75}=6.81kg/c{m}^2$