This is problem $5,$ use as a reference, the major stress was $45$ kPa and minor was $15$ kPa

A triaxial specimen of loose sand is first consolidated non$-$hydrostatically, with $1=15\mathrm{.}0$ kPa and $3=10\mathrm{.}0$ kPa. The sample is then failed by holding the vertical stress constant and decreasing the horizontal stress$1$ with the drainage valve open. The angle of internal friction $($$)$ is $30$o and the cohesion $($c$)$ is zero.

a$)$ Draw the Mohr circles for both the initial at $$at failure$$ conditions.

b$)$ What will be the major and minor principal stresses at at failure?

ANSWER THIS QUESTION BELOW USING PROBLEM $5$ AS A REFERENCE

Another sample of the same sand tested in Problem $5$ is tested by holding the vertical

stress constant and increasing the horizontal stress$2$ with the drainage valve open.

a$)$ Draw the Mohr circles for both the initial at $$at failure$$ conditions.

b$)$ What will be the major and minor principal stresses at at failure?