Question $2$: Strain analysis in two dimensions $(2$D$)$

$2\mathrm{.}1.$ Define principal strain and discuss its importance in rock mechanics.

$(4)$

$2\mathrm{.}2.$ Explain deviatoric strain and its significance in the context of rock fracturing.

$2\mathrm{.}3.$ Calculate the deviatoric strain given the major principal strain is $0\mathrm{.}005$ and the minor principal strain is $0\mathrm{.}002.$

$2\mathrm{.}4.$ Develop a Mohr circle using the given strain components for a rock mass: ${}_x=3{10}^{-3}$;${}_y=12{10}^{-3}$;${}_{xy}=14{10}^{-3}$ plot the Mohr circle and relate the maximum and minimum normal strains, as well as the maximum shear strain.

$[20]$