$(18$ points$)$ A retaining wall is shown in Figure $1.$ Given: $H=9m,H_1=4m,$

$q=20$kPa,${}_1=17k\frac{N}{m^3},c_1=12$kPa,${}_1=24$;$,{}_{\text{s}\text{a}\text{t}}=20k\frac{N}{m^3},c_2=0,{}_2=30,$

Determine the Rankine active earth pressure $E_a,$ and the water pressure $E_w,$

Draw the distribution curve of Rankine active earth pressure and pore water

pressure, and calculate the total lateral pressure $P_t.$

Figure $1$

Solution: