(Solved): A 5m high inverted-L cantilever retaining wall supports a backfill with a levelled platform of 4m ...

A 5m high inverted-L cantilever retaining wall supports a backfill with a levelled platform of 4m high. The base of the retaining wall is 1.5m long and lies on ground level. The thickness of stem and base slab is 0.4m. An external horizontal load of 25kN/m is applied at 2m above the ground level. Adopting Rankine's theory in calculating lateral earth pressures. Take density of concrete as 24kN/m. The material parameters for the backfill are o’=32°, c=0, 7-16kN/m². The material parameters for the founding soil are °°-38°, c=4kPa, y=20kN/m². 25kNm (a) By tabulating the forces and moments acting on the retaining wall, calculate the Factor of Safety against overturning and sliding. (Adopt db=0.80) (b) Suppose the external horizontal load of 25kN/m is provided by a 9m long horizontal soil nail (0° inclined to horizontal), which is made up of a Grade 500B steel bar of 16mm diameter in 120mm diameter drillhole. (i) By considering the wedge angle at Rankine's active limiting state as shown, determine the bond length of the soil nail. 25kNm 9m (ii) Adopting the bond length (i) and a factor of safety 1.5, is the soil nail provision capable to provide an external load of 25kN/m without failure along soil-grout interface? State your view and justify your answer.