A soil profile consists of 12 m of gravel overlying a clay layer of 3.5 m thickness,which in turn rests on a 4 m sand layer. The dry and saturated unit weights of thegravel are 17.5 kN/m3 and 20.5 kN/m3. Unit weights of the clay and the sand are20 kN/m3 and 19.5 kN/m3 respectively. Below the sand layer lies impermeablebedrock. If a wide excavation of 3 m depth is to be made in a relatively short time,draw the effective, total and pore pressure diagrams before and a long time afterthe excavation is made. Ground water table is 5 m below the ground surface.

The soil profile at a site consists of 10 m of gravelly sand underlain by a soft clay layer. The water table lies 1 m below the ground level. The moist and saturated unit weights of the gravelly sand are 17.0 kN/m3 and 20.0 kN/m3, respectively. Due to some ongoing construction work, it is proposed to lower the water table to 3 m below the ground level. What will be the change in the effective stress on top of the soft clay layer?

Redo Problem 6.12 using Figure 6.15. 6.12 Refer to Problem 6.1. Using Eqs. (6.3) and (6.29), estimate the average stress increase (av) below the center of the loaded area between depths of 3 m and 6 m. 6.1 A flexible circular area is subjected to a uniformly distributed load of 150 kN/m2 (Figure 6.2). The diameter of the load area is 2 m. Determine the stress increase in a soil mass at points located 3 m below the loaded area at r = 0, 0.4 m, 0.8 m, and 1 m. Use Boussinesqs solution. Figure 6.2 Increase in pressure under a uniformly loaded flexible circular area