Question $8.(15$ marks$)$

A retaining wall of $5m$ height is shown in the Figure $4$ below, the soil behind the wall is clayey soil with

the following properties: Effective shear strength parameters: $c^{\text{'}}=15$kPa,${}^{\text{'}}=25.$ Total shear strength

parameters: cu $=65$kPa. The soil unit weight is $20\mathrm{.}93k\frac{N}{m}3.$

$($i$)$ Calculate and plot the active pressure distribution diagram for both short$-$term and long$-$term cases

assuming active case. Use Rankine's approach.

$($ii$)$ Comment on the pressure distribution diagram for both the cases. For which one of these cases do

you need a greater width and breadth for the retaining wall, providing reasons $($without any

calculations$)?$

$($iii$)$ For the same problem how would the pressure distribution diagrams change if it is a passive case for

both short term and long term. Draw the pressure distribution diagrams without performing ahy

calculations. $($iv$)$ In which case there would a greater tension crack for the four scenarios: $($i$)$ Total Stress

Approach $($TSA$)$: active case;

$($ii$)$ TSA: passive case; $($iii$)$ Effective Stress Approach $($ESA$)$: active case; $($iv$)$ ESA: passive case? Provide

justification for your choice.