Question

In a falling head permeameter test on a silty clay sample, the following results were obtained;
sample length 120mm; sample diameter 80mm; initial head $1200mm$; final head $400mm$; time for fall in head $6$ minutes stand pipe diameter $4mm$. The coefficient of permeability of the soil is_____ $\times {10}^{-4}$ mm/sec

• A. 9.155

Answer 1

The correct option is A 9.155

In falling had test, coefficient of permeability

$K=\frac{aL}{At}ln\frac{h_1}{h_2}$

$=\frac{\frac{\pi }{4}(4{)}^2\times 120}{\frac{\pi }{4}(80{)}^2\times 6\times 60}\times ln\frac{1200}{400}$

$k=9.155\times {10}^{-4}mm/sec$