QUESTION

A retaining wall $6$ m high with a vertical back face retains a horizontal homogeneous saturated soft clay. The saturated unit weight of the clay is $19k\frac{N}{m^3}.$ Laboratory tests showed that the undrained shear strength, $c_u$ of the clay is $16\mathrm{.}8k\frac{N}{m^2}.$

a$.$ Do the necessary calculations and draw the variation of Rankine's active pressure on the wall with depth.

b$.$ Find the depth up to which a tensile crack can occur.

c$.$ Determine the total active force per unit length of the wall before the tensile crack occurs

d$.$ Determine the total active force per unit length of the wall after the tensile crack occurs. Also find the location of the resultant.