# GATE Papers >> Civil >> 2018 >> Question No 54

Question No. 54

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 ______

##### Answer : 1.00 to 1.03

Solution of Question No 54 of GATE 2018 Civil Paper

$\begin{array}{l}\mathrm{FOS}=\frac{\mathrm{Buoyant}\;\mathrm{weight}}{\mathrm{Seepage}\;\mathrm{force}}\\\mathrm{FOS}=\frac{{\mathrm\gamma}_\mathrm{sub}\times10}{10\times{\mathrm\gamma}_\mathrm w}=\frac{20-10}{10}=1\end{array}$