Test: Mohr - Coulomb Failure Theory

If the normal and shear stress corresponding to failure are plotted, then a curve is obtained .The plot or the curve is called the strength envelope.

Coulomb defined the function F (σ) as a linear function of σ and gave the following strength equation:
S = c + σ tan φ.

According to Mohr’s strength theory, the critical shear stress causing failure depends upon the properties of the materials as well as on normal stress on the failure plane.

The theory of failures was first expressed by coulomb in 1776 and later generalized by Mohr.

The Mohr-Coulomb failure theory can be expressed algebraically by the equation:τf = s = F (σ)
Where, τf = s=shear stress on failure plane, at failure=shear resistance of material
F (σ) = function of normal stress.