Question

Construction of a new building founded on a clayey soil was completed in January 2010. In January 2014, the average consolidation settlement of the foundation in clay was recorded as 10 mm. The ultimate consolidation settlement was estimated in design as 40 mm. Considering double drainage to occur at the clayey soil site, the expected consolidation settlement in January 2019 (in mm, round off to the nearest integer) will be

• A. 15

Answer 1

The correct option is A 15
Ultimate consolidation = 40 mm

Recorded consolidation = 10 mm

$\therefore U\%=\frac{10}{40}\times 100=25\%$

$\therefore U=0.25$

$T_V=\frac{\pi }{4}{U}^2=\frac{C_{v}t}{H^2}$

$\left[\begin{array}{cc}{t}_1=4yrs;& U_1=0.25\\ t_2=9yrs;& U_2=?\end{array}\right]$

$\therefore U^2\alpha t$

$\frac{U_1^2}{U_2^2}=\frac{t_1}{t_2}$

$\Rightarrow \frac{(0.25{)}^2}{U_2^2}=\frac{4}{9}$

$\Rightarrow \frac{0.25}{U_2}=\frac{2}{3}\Rightarrow U_2=0.375$

$\therefore$ Total recorded consolidation

$\Rightarrow 40\times 0.375$

$\Rightarrow 15mm$