$24$

A $500mm$ square driven pile is to be emplaced into a firm clay to a depth of $20m,$ the undrained shear strength of the clay at the base and top of the pile are $210k\frac{N}{m^2}$ and $45k\frac{N}{m^2}$ respectively. is measured as $0\mathrm{.}65$ for the pile as a whole. Calculate the ultimate undrained bearing capacity of the pile. $($divide into $4$ layers$).$