Question

A canel having side slopes 1 : 1 is proposed to be constructed in a cohesive soil to a depth of 10m below the ground surface. The soil properties are ${\varphi }_u={15}^{\circ },c_u=12kPa,e=1.0,G=\mathrm{2.65.}$

IF there is a sudden drawdown of water in the canel and if Taylor's stability number for the reduced value of ${\varphi }_w$ is 0.126, the factor of safety with respect to against the failure of bank will be

• A. 1.85
• B. 1.18
• C. 0.84
• D. 0.532

Answer 1

The correct option is D 0.532

If there is sudden drawdown of water in canel, soil will be in saturated condition

${\gamma }_{sat}=\left(\frac{G+e}{1+e}\right){\gamma }_w$

$=\left(\frac{2.65+1}{1.1}\right)\times 9.81$

$=17.903KN/m^3$

Taylor stability number,

$S_n=\frac{C_u}{{\gamma }_{sat}H.FOS}$

$0.126=\frac{12}{17.903\times 10\times FOS}$

$\Rightarrow FOS=0.532$