A retaining wall $12$m high has horizontal backfill on its vertical face to its base.

Under normal conditions, the backfill has a water content of $10\%$and a void ratio of $0\mathrm{.}50.$The

specific gravity of the soil grains is $2\mathrm{.}50$and the angle of internal friction is $20$degrees$.$ Using

Rankine$$s theory of lateral earth pressure, Evaluate the total horizontal lateral force per meter width of wall, in kN$,$ due to the soil. the answer is $288\mathrm{.}59$ kN show the solution