At a construction site, a contractor plans to make an excavation as shown in the figure

Q. At a construction site, a contractor plans to make an excavation as shown in the figure.

The water level in the adjacent river is at an elevation of +20.0 m. Unit weight of water is 10 kN/m³. The factor of safety (up to two decimal places) against sand boiling for the proposed excavation is

Ans: 1.00 – 1.03

Sol:

 For Quicksand condition, effective stress in the soil becomes zero (σ = 0)

At the bottom of the soil column,