Consider a wall and retained soil mass shown in the figure below. Due to heavy rainfall,

the water level rose to $1$ m below the ground surface.

a$.$ Calculate the coefficient of active lateral earth pressure $K_A$ for both layers $(5$

points$)$

b$.$ Calculate and plot the distribution of the vertical effective stress and active lateral

effective stress behind the wall $(15$ points$)$

c$.$ Plot the water pressure distribution behind the wall $($Assume the unit weight of

water points$)$

d$.$ Calculate the total resultant lateral force $($resulting from both soil pressure and

water pressure$)$ that acts on the back of the wall $(10$ points$)$

e$.$ Calculate the distance from the resultant force to the base of the wall $(5$ points$)$