The two dimensional principal stress state at two points in a homogeneous rockmass are shown below:

$3\mathrm{.}1$ Define the following $($make use of sketches if required$)$:

$(10)$

i$.$ Normal stress

ii$.$ Shear stress

iii. Homogeneous rockmass

iv$.$ Lithostatic stress conditions

v$.$ Principal stress

$3\mathrm{.}2$ If the fault has a friction angle of $30$ and cohesion of $1\mathrm{.}0$MPa, comment on its stability at Point $1.$ Show all calculations.

$3\mathrm{.}3$ What out$-$of$-$plane stress $({}_3)$ is required at Point $2$ to satisfy the plain strain assumption? $($Assume $v=0\mathrm{.}3)$

$(5)$