Figure $2.$A $6\mathrm{.}5m$ high temporary retaining wall with $4$ struts is to be constructed. Soil profile can be idealized as soft clay $($CL$).$ Natural unit weight of the soil $({}_n)$ is $17k\frac{N}{m^3}.$ The upper strut is located $0\mathrm{.}5m$ below the top of the wall and the vertical distances between struts are $1\mathrm{.}5m.$ The center$-$to$-$center spacing of struts is $3\mathrm{.}0m.$ A cross section view of the initial design for the wall including the struts and soil properties are shown in Figure $2.$

a$)$ Calculate the forces acting on each strut.

b$)$ What is the factor of safety bottom against heave?