As shown in Figure 1, a sheet pile has been driven 5m into saturated sand layer to retain 7 m of backfill. The backfill consists of two layers: 4 m of coarse sand and 3 m of silty clay. A surcharge pressure of 100 kPa was applied to backfill to pre-consolidate the silty clay layer. The total active lateral pressure at 12 m depth is: (Assume Rankine conditions are satisfied) Sheet pile Wall 4 m Sm 3 m Figure 1 q=100kN/m Coarse Sand 7-20kN/m c'=0 @-30 Sity clay soil 7-18kN/m #-15 e-30 kPa Sand 7=22 kN/m c'=0 -27 Rankine's Active earth pressure x=K0-20K X/A sind 1+sin- Rankine's Passive earth pressure xip=Ko'z+2K sind sin