Question $8$ b$.$

$4$ Marks

A retaining wall $10\mathrm{.}0m$ high retains sandy backfill. The backfill properties from top of the wall upto $4m$ is $=30$ degree, $=20k\frac{N}{m^3}$ and from $4m$ to $10m,$ is $40$ degree and $=20k\frac{N}{m^3}.$ Determine the lotal active thrust and its point of applicatipn. Also calculate the active earth pressure at the top, $4m$ and $10m$ from the top of the wall