Explain how to solve When X$=6$

Q$4.$

$($a$)$ A ore$-$dimensional laboratory consolidation test was performed on a soil sample. The height of the sample was $25\mathrm{.}4mm.$ The time required for $50\%$ consolidation was $)$ minutes $(x$ is your group number$).$ Find the coefficient of consolidation $($Cv$).$

$($b$)$ If the soil sample in $($a$)$ above was taken from a clay layer shown below. The total consolidation settlement due to structural load was computed to be $18cm.$

$($i$)$ What is the time for $50\%$ consolidation?

$($ii$)$ How much settlement will occur in $0\mathrm{.}75$ years?

Ground surface

Bedrock

A soil sample was taken from the clay layer shown in the figure below. The sample was tested in the laboratory using the $1-$dimensional consolidation laboratory test $($oedometer$).$ The sample height was $20mm$ and the time for $90\%$ consolidation was $(50-2x)$ minutes.

$($i$)$ Compute $C_v$ in $\frac{m^2}{y}$ear

$($ii$)$ What will be the time for $90\%$ consolidation in the field?

$($iii$)$ If the total consolidation settlement is $50mm,$ how much settlement will occur in the field in $2$ years?

$($iv$)$ If there is sand instead of the bedrock and there is a thin sand layer $(40cm$ thick$)$ at the middle of the clay layer. What effect this thin sand layer will have on the time

Bedrock