Question

In a consolidation test, the thickness of saturated specimen of clay under over burden pressure of $150kN/m^2$ is 30 mm at water content of 20%. On increasing the consolidation pressure to $250kN/m^2$, the sample thickness decreases to 25 mm after consolidation. If specific gravity of clay is 2.7 the compression index of the clay.

• A. 1.16
• B. 2.32
• C. 5.98
• D. 0.15

Answer 1

The correct option is A 1.16

${\sigma }_0^{\prime }=150kN/m^2$

${\sigma }^{\prime }=250kN/m^2$

$H_1=30mm$

$w=20\%$
$H_2=25mm$
$G=2.1$
$C_c=?$

$\therefore e_0{S}_r=w.G$

$e_0=0.2\times 2.7$

$e_0=0.54$

$\therefore \frac{\Delta H}{H}=\frac{\Delta e}{1+e_0}$

$C_c=\frac{\Delta e}{lo{g}_{10}\left(\frac{{\sigma }^{\prime }}{{\sigma }_0^{\prime }}\right)}$

$\frac{\Delta H}{H}=\frac{C_c}{1+e_0}\times lo{g}_{10}\left(\frac{{\sigma }^{\prime }}{{\sigma }_0^{\prime }}\right)$

$\frac{30-25}{30}=\frac{C_c}{1+0.54}\times lo{g}_{10}\left(\frac{250}{150}\right)$

$C_c=1.16$