Question

Water is flowing at a rate of 0.04 m^3/s in a soil sample of 12m thick and cross section of 50m^2. The coefficient of permeability is 1.6*10^-3m/s. What will be the seepage force per unit volume?

(a) 4.9 kN/m^3

(b) 3.9 kN/m^3

(c) 4.1 kN/m^3

(d) 3.2 kN/m^3

The question was posed to me by my college director while I was bunking the class.

My question is based upon Seepage Pressure and Upward Flow in division Seepage Analysis of Geotechnical Engineering I

Answer 1

The correct answer is (a) 4.9 kN/m^3

Easiest explanation: Given,

Discharge q=0.04 m^3/s

z=12m

Area A=50 m^2

coefficient of permeability k=1.6*10^-3m/s

the hydraulic gradient i is given by,

i=q/(kA)

i=0.04/(50*1.6*10^-3)

i=0.5

The seepage force per unit volume j is given by,

j=iγw

j=0.5*9.81

∴j=4.9 kN/m^3.