Question a$.5\%,0\mathrm{.}5\%,$ c$.2\%0$

The initial excess pore water pressure over a fully saturated clay layer of $5m$ thickness is $75k\frac{N}{m^2}.$ Variation of the remaining excess pore water pressure in the clay layer at a given time following the start of consolidation is plotted on the figure below.

a$)$ What type of boundary conditions exist on top and bottom of the clay layer? Hint: consider the shape of excess pore water pressure distribution curve.

b$)$ What are the degrees of consolidation $U_z,$ at depths $z=0$ and $z=2\mathrm{.}5m$ in the clay layer?

c$)$ If the shaded area in the above figure is $337\mathrm{.}5k\frac{N}{m},$ determine the average degree of consolidation for the complete layer.