The gravity wall shown below is to support backfill with unit weight of 19.5 kN/m and shear strength parameters c' = 0 kPa and 0' = 36 (shear strength parameters were determined using triaxial laboratory tests). The unit weight of the wall material is 24 kN/m and the friction angle between the wall and the backfill 8 = 27 and at the base of the wall it is 25. Determine the factors of safety against (i) sliding on the base (ii) overturning, and (iii) bearing capacity failure, and compare these against minimum desirable values of 1.5, 1.5 and 3.0 respectively (the soil below the wall can be assumed as similar to the backfill soil). If any of the FOS are inadequate, redesign the wall (while maintaining the same height and concrete volume) so as to satisfy the minimum FOS requirements. Show a dimensioned sketch and clearly set out all necessary calculations for your modified design. 5 m 1.62 m 15 100 . 2.50 m Figure 1: The geometry of the mass gravity retaining wall