Question

The plate load test conducted with a 75 cm diameter plate on soil subgrade yielded a deflection of 2.5 mm under a stress of 800 N/$c{m}^2$.

The modulus of elasticity of the subgrade soil, in kN/$c{m}^2$ is

• A. 160.0
• B. 141.6
• C. 185.4
• D. 154.6

Answer 1

The correct option is B 141.6

Deflection of rigid plate,

$\Delta$ = 2.5 mm = 0.25 cm

Stress, $\sigma$ = 800 $N/c{m}^2$

= 0.8 k$N/c{m}^2$

Radius of plate, r = $\frac{75}{2}$ = 37.5 cm

For rigid plate, $\Delta$ = $\frac{1.18\sigma r}{E_s}$

Modulus of elasticity of subgrade soil,

$E_s=\frac{1.18\times 0.8\times 37.5}{0.25}$

= 141.6 kN/$c{m}^2$