OUESTION $3($Earth Retaining Structures$)$

$[18$ Marks$]$

$($a$)$ For the retaining structure shown above calculate the safety factor against overturning about the toe at $A,$ assuming the backfill is cohesionless and well drained. Take the unit weight of the backfill as $18k\frac{N}{m^3},$ the angle of internal friction $30,$ and the unit weight of concrete as $24k\frac{N}{m^3}.$

$(10)$

$\backslash$table$[[$Weight$,$Arm,Moment$],[$W$\_(1)=,,],[$W$\_(2)=,,],[$W$\_(3)=,,],[$W$\_(4)=,,],[,,],[$W$\_($S$)=,,],[,,]]($b$)$ Calculate the overturning moment about the toe of the wall in $($a$)$ above caused by the earth pressure if the backfill surface was not horizontal, but sloped upwards from the tip of the wall at a slope of $1(V)$:$2(H).$

$(8)$

$11$