A 5-m-high concrete retaining wall has a cross section as depicted in Figure 25. The top of the wall is 1 m wide, and the base of the wall is 2 m wide. The backfill is a granular soil, with a unit weight equal to 18 kN/m3 and an angle of internal friction equal to 35 degrees. The backfill surface is level. Using criteria shown in Figure 18(a), calculate the factor of safety against overturning and sliding for this wall.

Assume that the lateral force due to the backfill acts at an angle of 25° from the horizontal (for computing the horizontal and vertical components of the earth pressures force). To check sliding among the base, assume that the coefficient of friction is equal to the value for the tangent of the angle of internal friction. The unit weight for concrete in the wall is 22.75 kN/m3.