![At a construction site, a contractor plans to make an excavation as shown in the figure](https://www.gkseries.com/blog/wp-content/uploads/2023/09/At-a-construction-site-a-contractor-plans-to-make-an-excavation-as-shown-in-the-figure.jpg)
Q. At a construction site, a contractor plans to make an excavation as shown in the figure.
![](https://www.gkseries.com/blog/wp-content/uploads/2023/09/Screenshot-920.png)
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,
![](https://www.gkseries.com/blog/wp-content/uploads/2023/09/Screenshot-921.png)