a$)$ Identify all forces acting on the circular failure wedge shown in Fig. $2.$ Identify the location of the resultant forces and lever arms for moment equilibrium about Point O$.$ Submit as a labelled diagram or sketch. Note that you do not have to redraw Fig. $2.$ It would be acceptable to neatly and clearly revise the supplied drawing$($s$),$ and then scan and paste into your submission.

b$)$ Derive and report a limit equilibrium expression for embankment stability based on moment equilibrium about Point O$.$

c$)$ What average shear strength was mobilized during failure of the embankment? For the embankment soil, take $=21$ kN$/$m$3$ and $\text{'}=30$o $.$ Take $=16$ kN$/$m$3$ for the soft clay.