Question

A strata of 3.5 m thick fine sand has a void ratio of 0.7 and G of 2.7. For a quick sand condition to develop in this strata, the water flowing in upward direction would require a head of

• A. 7 m
• B. 5.56m
• C. 5 rn
• D. 3.5 m

Answer 1

The correct option is D 3.5 m

The critical hydraulic gradient,

$i_c=\frac{G-1}{1+e}=1.0$

For quick sand condition

$i=i_c=\frac{h}{L}$

$h=1.0\times \times 3.5=3.5m$