Triaxial tests performed on several rock specimen from the same granite unit, with the following results for stresses at failure: $\begin{array}{cc}\text{s}\text{i}\text{g}\text{m}\text{a}3(MPa)& \text{s}\text{i}\text{g}\text{m}\text{a}1(MPa)\\ 5& 140\\ 10& 170\\ 15& 210\end{array}40260$

a$.$ Plot the Mohr circles for failure.

b$.$ Plot the data in sigma$(3)$ vs sigma$(1)$ space

c$.$ Estimate what the unconfined compressive strength would be

d$.$ Determine the Mohr$-$Coulomb failure envelope equation.

e$.$ Determine the Hoek$-$Brown failure envelope equation.