Determine the downward column load that can be supported by a square single pile installed in a soil with the properties given: Friction angle, ¢ = 25 ° ,Unit weight, Y = 17 kN/m3, Undrained cohesion, Cu = 85 kN/m2. The pile size is 0.36m x 0.36m, the pile length is 18.0 m and the allowable factor of safety is 2.5.