Question

The velocity with which the excess pore water flows is _________

(a) \(v=\frac{k}{2}\frac{∂\overline{u}}{∂z}\)

(b) \(v=\frac{1}{γ_w}\frac{∂\overline{u}}{∂z}\)

(c) \(v=\frac{k}{γ_w}\frac{∂\overline{u}}{∂z}\)

(d) \(v=\frac{∂\overline{u}}{∂z}\)

This question was addressed to me in exam.

The query is from Stress Distribution in portion Stress Distribution of Geotechnical Engineering I

Answer 1

Correct answer is (c) \(v=\frac{k}{γ_w}\frac{∂\overline{u}}{∂z}\)

Easy explanation: The velocity with which the excess pore water flows is given by Darcy’s law,

\(v=ki, \,where\, i=\frac{1}{γ_w}\frac{∂\overline{u}}{∂z}\)

Therefore, \(v=\frac{k}{γ_w}\frac{∂\overline{u}}{∂z}.\)