A 5 m high smooth vertical wall retains a clay backfill with c' = 10 kN/m 2 , ' = 25, and = 19.0

A 5 m high smooth vertical wall retains a clay backfill with c' = 10 kN/m², ϕ' = 25°, and γ = 19.0 kN/m³. If the clay is in active state, determine the following:

a. The maximum tensile stress within the clay

b. The depth of the tensile cracks

c. The magnitude and location of the active thrust, neglecting the tensile zone