Question

The Mohr–Coulomb failure criterion is mainly used to describe:

• A. Elastic behavior of rocks
• B. Plastic flow of rocks
• C. Shear failure of rocks
• D. Tensile failure of rocks

Hint:

Mohr–Coulomb criterion links shear stress, normal stress, cohesion, and friction angle to predict rock failure.

Answer 1

The Correct Option is C

Step 1: Understanding the Mohr–Coulomb failure criterion.
The Mohr–Coulomb failure criterion is a widely used theory in rock mechanics and geotechnical engineering to predict the failure of materials such as rocks and soils under stress.
Step 2: Stress components involved.
The criterion relates the shear stress acting on a plane to the normal stress on that plane, along with material properties such as cohesion and angle of internal friction.
Step 3: Nature of failure described.
According to the Mohr–Coulomb theory, failure occurs when the shear stress exceeds the shear strength of the rock material. Hence, it primarily explains shear failure rather than elastic or tensile behavior.
Step 4: Analysis of the given options.
(A) Elastic behavior of rocks: Elastic behavior occurs before failure and is not described by this criterion.
(B) Plastic flow of rocks: Plastic deformation is not the main focus of the Mohr–Coulomb model.
(C) Shear failure of rocks: Correct — the criterion predicts failure due to shear stress.
(D) Tensile failure of rocks: Tensile failure is described by different criteria.
Step 5: Conclusion.
The Mohr–Coulomb failure criterion is mainly used to describe shear failure of rocks.