In a sieve analysis of a soil sample, the effective size corresponding to particles that are 10% finer (D10) is 0.6 mm, the particle size corresponding to 30% finer (D30) is 1.2 mm, and the particle size corresponding to 60% finer (D60) is 3.0 mm. What is the coefficient of curvature (Cc) of the soil?

A rigid retaining wall 5 m high is restrained from yielding. The backfill consists of cohesionless soil having φ' = 30° and unit weight of soil γ = 18 kN/m3. Compute the total earth pressure per metre length of the wall at rest. (Consider sin(30°) = 0.5, cos(30°) = 0.866)

Calculate the average contact pressure (in kN/m2) directly beneath a square footing of dimensions 4 m × 4 m carrying a vertical load of 200 kN.