Question $2$

$($a$)$ Figure $2$ below shows the cross$-$section of a proposed cut in a saturated clay soil. The area

ABCDEA is $155m^2$ and its centroid is at G$.$ If the tension crack CD is full of water, calculate

the factor of safety for the slip circle shown. Relevant dimensions and soil properties are shown

in the diagram. Briefly comment on whether you think this factor of safety is adequate $($note that

some additional dimensions may need to be calculated based on those given$).$

NEC$2202$ Geomechanics

Figure $2$: The slip circle and geometries of the slope

$($b$)($i$)$ What is the main difference between the Bishop's conventional method of slices and

Bishop's rigorous method of slices for effective stress analysis of slopes in $C,\frac{O}{?}$ soils?

$($ii$)$ Briefly describe two methods of drainage and groundwater control for slope stabilization

$($you may use sketches as required$).$