Problem $4(20$ Points$)$

A $15-$ft$-$thick layer of saturated NC clay under a surcharge loading underwent $60\%$ primary consolidation in $75$ days $($Water table at ground surface$).$

a$.$ Calculate the coefficient of consolidation $(C_v)$ of clay for the pressure range for both single and double drainage conditions.

b$.$ A uniformly distributed load $($fill$))=(500psf$ is applied at the top of the clay layer, determine the primary $($total$)$ consolidation settlement of the clay layer $,C_c=0\mathrm{.}25,e_o=0\mathrm{.}9)$

c$.$ Based on soil profile and lab testing, how can you differentiate between NC and OC clay?

d$.$ What is the time required for $2-$inch consolidation settlement under the uniform load given in part $($b$)$ if the clay layer has double drainage conditions?