$12\mathrm{.}15$ For a laboratory consolidation test on a clay specimen $($drained on both sides$),$ the

following were obtained.

Thickness of the clay layer $=25mm$

${}_1^{\text{'}}=200k\frac{N}{m^2},e_1=0\mathrm{.}73$

${}_2^{\text{'}}=400k\frac{N}{m^2},e_2=0\mathrm{.}61$

Time for $50\%$ consolidation $(t_{50})=2\mathrm{.}8$min

Determine the hydraulic conductivity of the clay for the loading range.

Answer:

$3\mathrm{.}84{10}^{-8}\frac{m}{m}in$