Question

A uniform collapsible sand stratum, 2.5 m thick. Has specific gravity of its sand as 2.65. With a natural void ratio of 0.65. The hydraulic head required to cause quick collapsible sand condition is

• A. 2.50 m
• B. 2.75 m
• C. 3.25 m
• D. 3.50 m

Answer 1

The correct option is A 2.50 m

Critical hydraulic gradient,

$i_{cr}=\frac{G-1}{1+e}=\frac{2.65-1}{1+0.65}=1$

Hydraulic gradient,

$i_{cr}=\frac{Head}{Length}=\frac{H}{2.5}=1$

Hydraulic head

$=2.50m$