Question

The deviator stress σd is given by __________

(a) σd = σ1 + σ

(b) σd = σ3 – σ1

(c) σd=additional axial load/A2

(d) σd = σ1 – σ3

This question was posed to me in examination.

This intriguing question originated from Tri-axial Compression Test in portion Shear Strength of Geotechnical Engineering I

Answer 1

Right answer is (c) σd=additional axial load/A2

To explain I would say: The deviator stress σd, is given as the ratio of additional axial load to the area A2 at failure or during at any stage of the test.