Question

When movement of a wall under the earth pressures from the backfill was prevented the coefficient of earth pressure was recorded as 0.5. The ratio of the coefficient of passive and active earth pressure of the backfill is

• A. 1/3
• B. 3
• C. 1/9
• D. 9

Answer 1

The correct option is D 9

$\begin{array}{cc}& \text{Coefficient of earth pressure at rest,}\\ 1-\sin \varphi & =K_0\\ \sin \varphi & =1-0.5\\ \sin \varphi & =0.5\\ \therefore \frac{K_p}{K_a}& ={\left(\frac{1+\sin \varphi }{1-\sin \varphi }\right)}^2={\left(\frac{1.5}{0.5}\right)}^2=9\end{array}$