A retaining wall 7 m high, retains a cohesion less backfill. The top 3 m of the fill has a unit weight of 18 kN/m3 and ϕ = 30° and the rest has a unit weight of 24 kN/m3 and ϕ = 20°. Find the total active force per unit length in kN if the water table is at 3m from top? (Take \({\gamma _w}\) = 10 kN/m3)
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