QUESTION $2)$ A $5m$ thick clay layer overlying an impermeable rock is consolidated under an overburden

pressure of $250$kPa. Because of a contemplated construction, pressure increase of $150$kPa is expected.

Consolidation tests on an undisturbed specimen from the field indicate that, for ${}_1=250$kPa,$e_1=0\mathrm{.}94$ and

for ${}_2=400$kPa,$e_2=0\mathrm{.}90.$ If the permeability of the clay layer is $k=1\mathrm{.}2{10}^{-6}c\frac{m}{sec},$

a$)$ What is the total settlement?

b$)$ What is the probable period for reaching a consolidation ratio of $50\%?$ Assume constant initial pwp

distribution.