Question

For a saturated sand deposit, the porosity and the specific gravity of solids are 40% and 2.7 respectively. The critical hydraulic gradient at which boiling starts is:

• A. 0.98
• B. 1.02
• C. 1.08
• D. 1.21

Answer 1

The correct option is B 1.02

$i_c=\frac{G-1}{1+e}$
Given, n = 40%
G = 2.7
$e=\frac{n}{1-n}=\frac{0.4}{0.6}=\frac{2}{3}$
$\therefore i_c=\frac{1.7}{1+\left(\frac{2}{3}\right)}=1.02$