Question

A constant-head permeability test was conducted on a soil specimen under a hydraulic gradient of 2.5. The soil specimen has specific gravity of 2.65 and saturated water content of 20%. If the coefficient of permeability of the soil is 0.1 cm/s, the seepage velocity (in cm/s, round off to two decimal places) through the soil specimen is

• A. 0.72

Answer 1

The correct option is A 0.72
Given,

Hydraulic gradient (i) = 2.5

G = 2.65

w = 20% = 0.2

Coefficient of permeability (k) = 0.1 cm/s

According to Darcy law

v = k $\times$ i

= 0.1 $\times$ 2.5

= 0.25 cm/s

We know that

Se = wG (S = 1)

e = 0.2 $\times$ 2.65 = 0.53

porosity (n) =

$\frac{e}{1+e}=\frac{0.53}{1+0.53}=0.346$

$Seepagevelocity\left(v_s\right)=\frac{v}{n}$

$=\frac{0.25}{0.346}=0.72cm/s$