Question

For a foundation, find the elapsed time in which 10% of ultimate settlement will occur.  The coefficient of consolidation is 4*10^-4cm^2/s. The average drainage path is 50cm.

(a) 19.9 hours

(b) 15.5 hours

(c) 13.9 hours

(d) 17.5 hours

This question was addressed to me during an internship interview.

The query is from Consolidation Problems topic in chapter One Dimensional Consolidation of Geotechnical Engineering I

Answer 1

The correct option is (c) 13.9 hours

For explanation: Given,

d=50 cm

Cv=4×10^-4 cm^2/s

For consolidation of 10%, U<60%

Tv=\(\frac{π}{4} (\frac{v}{100})^2=\frac{π}{4} (\frac{10}{100})^2=0.008\)

Therefore time elapsed \(t_{10}=\frac{(T_v)_{10} d^2}{C_v} = \frac{0.008×(50)^2}{4×10^{-4}} s = 13.9 hours.\)