(Solved): A strip rigid footing as shown in Figure Q4(b) is to be constructed at a depth of 2.0 m below groun ...

A strip rigid footing as shown in Figure Q4(b) is to be constructed at a depth of 2.0 m below ground level in sand. The ground water level is assumed to be 0.5 m below ground level. The load of 200 kPa is uniformly spread on this rigid footing. The increase in effective stress at the middle of the clay layer can be determined using the 2:1 method of load spreading. 6m (B) x 8m (L) Sand % -19 kN/m² -20 kN/m² Clay %? a. an av 3.0 2.5 2.0 1.5 1.0 0.5 -20 kN/m² -22 kN/m² C -0.2 Impervious rock D.G.W. 2 H-0.25 G.L. E.-28000kN/m² 7 m <,-0.45 Figure Q.4(b): Shallow foundation centre of flexible footing average for flexible footing a rigid footing a 7 Df=2m For circular foundation a=1 a=0.85 a=0.88 L/B Figure Q.4(c): Value of a, ar, dav 5m (i) Determine the immediate settlement (S.) for the sand layer due to the footing (5 marks) load. (ii) Determine the ultimate consolidation settlement (Sc) for the clay layer due to the foundation load by using Figure Q.4(c). (5 marks)