Question

The cirtical slip circle for a slope is shown below along with the soil properties. $(c=30KN/m^2)$

The length of the arc of the slip circle is 15.6 m and the area of soil within the slip circle is $82m^2$. The radius of the slip circles is 10.3m, The factor of safety against the slip circle failure is nearly equal to

• A. 1.05
• B. 1.22
• C. 0.78
• D. 1.28

Answer 1

The correct option is D 1.28

$FOS=\frac{Resistingmoment}{Actuatingmoment}$

$=\frac{c\times l\times r}{W\times 2.3}...\left(1\right)$

Wt. of soil inside the slip circle

$W=Area\times$ $\gamma$ $\times$ 1

$=82\times$ 20 $\times$ 1

= 1640 KN

From (i)

$FOS=\frac{30\times 15.6\times 10.3}{1640\times 2.3}$

= 1.28