Please answer C$,$ D and E$.$ A sand layer, $10$ meters thick, overlies $($is above$)$ a $6$ meter thick normally consolidated

clay layer. There is an impermeable layer of rock below the clay layer. The ground water

table is located $2$ meters below the surface of the sand layer. A $3$ meter layer of fill,

having a unit weight $15$ KN$/$m $3,$ is to be placed on top of the existing sand layer.

The following properties of the soil layers are given:

SAND: Dry unit weight $=17$ KN$/$m$3$

Saturated unit weight $=19$ KN$/$m $3$

CLAY: Saturated unit weight $=20$ KN$/$m $3$

Coefficient of consolidation, c v $,$ is $1\mathrm{.}26$ m$2/$year

Compression index, C c $,$ is $0\mathrm{.}16$

Initial void ratio, e o $,$ is $0\mathrm{.}7$

A$.$ Sketch the problem

B$.$ Calculate the final settlement due to primary consolidation of the clay layer after

the fill has been placed.

C$.$ Determine the settlement due to primary consolidation of the clay layer three

years after the fill has been placed.

D$.$ How long will it take for the clay layer to reach $50\%$ consolidation?

E$.$ How long will it take for the clay layer to reach $50\%$ consolidation if the

thickness of the clay layer is doubled?