Question

Assertion (A): The safe height $\left(2z_0\right)$ to which an unsupported vertical cut in clay be made is $4c/\gamma .$
Reason (R): Active earth pressure of cohesive backfill shows that the negative pressure (tension) is developed at top level. This tension decrease to zero at depth $z_0$ and total net pressure up to a depth $2z_0$ is zero.

• A. both A and R are true and R is the correct explanation of A
• B. both A and R are true but R is not correct explanation of A
• C. A is true but R is false
• D. A is false but R is true

Answer 1

The correct option is A both A and R are true and R is the correct explanation of A

Tension is shown as negative and compression as positive.

$Forpureclay{K}_a=1.0$
$\therefore Lateralpressure=\gamma z-2c.$
$At{z}_0=\frac{2c}{\gamma }lateralpressurewillbezero.$