Engineering Questions with Answers - Multiple Choice Questions

# Mohr – Coulomb Failure Theory

1 - Question

The curve obtained by plotting the normal and shear stress is called as ___________
a) Mohr’s envelope
b) Coulomb envelope
c) Strength envelope
d) Stress envelope

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

2 - Question

Which of the following is coulomb’s strength equation?
a) S = c + tan φ
b) C = s + c tan φ
c) S = c + σ tan φ
d) S = tan φ

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

3 - Question

The critical shear stress causing failure of material depends upon ____________
a) Properties of the material and normal stress on the plane
b) Intermediate principal stress
c) None of the mentioned
d) All of the mentioned

Explanation: 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.

4 - Question

Theory of failure, was first proposed by ____________
a) Coulomb
b) Mohr
c) Casagrande
d) Darcy

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

5 - Question

The Mohr-Coulomb theory can be expressed algebraically by, which of the following equation.
a) S = c + σ tan φ
b) τf = s = F(σ)
c) s = F(σ)
d) τf = F(σ)

Explanation: 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.

6 - Question

According to Coulomb, the relationship between shear strength and normal stress could be represented by _________
a) Linear curve
b) Parabolic curve
c) Straight line
d) None of the mentioned

Explanation: Coulomb considered that the relationship between shear strength and normal stress could be adequately represented by the straight line.

7 - Question

Mohr envelope can be considered to be straight if the angle of internal friction φ is assumed to be __________
a) 90°
b) >90°
c) <90°
d) None of the mentioned

Explanation: Mohr envelope can be considered straight if the angle of internal friction φ is assumed to be a constant.

8 - Question

Which of the following stresses does not have any influence on strength of a material?
a) Major principal stress
b) Minor principal stress
c) Intermediate principal stress
d) Shearing stress

Explanation: When a material is subjected to three dimensional stresses, the intermediate principal stress does not have any influence on the strength of material.

9 - Question

The parameter φ in coulomb’s equation “S = c + σ tan φ”, represents ___________
a) Shearing resistance and Angle of internal friction
b) Angle of slope
c) None of the mentioned
d) All of the mentioned