Question

In a drained triaxial compression test, a saturated specimen of a cohesionless sand fails under a deviator stress of $3kgf/c{m}^2$ when the cell pressure is $1kgf/c{m}^2$. The effective angle of shearing resistance of sand is about

• A. ${37}^{\circ }$
• B. ${45}^{\circ }$
• C. ${53}^{\circ }$
• D. ${20}^{\circ }$

Answer 1

The correct option is A ${37}^{\circ }$

Given

${\sigma }_3=1kgf/c{m}^2$

${\sigma }_1-{\sigma }_3=3kgf/c{m}^2$

${\sigma }_1-1=3$

${\sigma }_1=4kgf/c{m}^2$

We know that

${\sigma }_1={\sigma }_{3}ta{n}^2(45+\frac{\varphi }{2})+2ctan(45+\frac{\varphi }{2})$

for sand, c = 0

${\sigma }_1={\sigma }_{3}ta{n}^2(45+\frac{\varphi }{2})$

$4=1ta{n}^2(45+\frac{\varphi }{2})$

$\varphi ={36.87}^{\circ }$

Hence the correct opition is (a).