Question

In a 1D compression test with double drainage, the pore pressure readings are practically zero after 8 minutes for a clay sample of 2 cm thickness. What will be the duration (in minutes) of the consolidation process for the same clay, if the test is done under single drainage condition?

Answer 1

Answer:

The duration of the consolidation process for the same clay is 32 min

Explanation:

for clay 1:

t1=0

H1=thickness=2 cm

for the clay 2:

t2=?

H2=2 cm

The time factor is equal to:

$T=(\frac{Cv}{d^{2} })t$

where Cv is the coefficient of consolidation

$(\frac{Cvt}{d^{2} })_{1}= (\frac{Cvt}{d^{2} })_{2}$

if Cv is constant, we have:

$(\frac{t1}{(\frac{H1}{2}) ^{2} })_{1}=(\frac{t2}{H2^{2} })_{2}\\\frac{0}{(\frac{2}{2})^{2}) }=\frac{t2}{2^{2} }$

Clearing t2:

t2=32 min