# Geotechnical Engineering Questions and Answers – Mohrs Stress Circle

This set of Geotechnical Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Mohrs Stress Circle”.

1. The shearing resistance of a soil is constituted by ___________
a) Structural resistance and Frictional resistance
b) Shearing strength
c) None of the mentioned
d) All of the mentioned

Explanation: The shearing resistance of soil is constituted by
i) The structural resistance to displacement of the soil because of the interlocking of the particles
ii) The frictional resistance to a translocation between the individual soil particles at their contact points.

2. The shear strength in cohesion less soil is due to ___________
a) Internal friction
b) Cohesion
c) Inter granular friction
d) Inter particle force

Explanation: The shear strength in cohesion less soils from inter granular friction, while in other soils it results both from internal friction as well as cohesion.

3. The planes that exist in soil mass is ______________
a) Principal plane
b) Principal stress
c) Stress plane
d) None of the mentioned

Explanation: In a loaded soil mass, there exist three typical planes, mutually orthogonal to each other. These planes are called the principal planes.

4. The failure condition for a soil can be expressed in terms of limiting shear stress, called __________
a) Principal stresses and Shear strength
b) Shearing resistances
c) None of the mentioned
d) All of the mentioned

Explanation: The failure conditions for a soil may be expressed in terms of limiting stress, called shear strength or as a function of the principal stresses.

5. The shear deformation of soil in a building can cause ___________ of the following?
a) Sinking of footing
b) Slide in an earth embankment
c) Movement of wedge
d) All of the mentioned

Explanation: Shearing deformation of soil may be in the form of the sinking of a footing, or movement of a wedge of soil particles or on masses upon the action of shear stress.

6. Major principal stress in a soil is represented by the symbol ________________
a) σ1
b) σ2
c) σ3
d) σ4

Explanation: Major, intermediate and minor principal stresses are represented by the corresponding symbols σ1, σ2, and σ3.

7. The circle obtained from two dimensional stress system is known as ________
a) Principal stress circle
b) Mohr circle
c) Shearing stress circle
d) None of the mentioned

Explanation: The circle drawn from two dimensional stress systems is known as Mohr’s circle of stress (Mohr, 1870).

8. The maximum shear stress τmax, for a soil mass is equal to ___________
a) (σ1 – σ3 )/2
b) (σ1 + σ3 )/2
c) (σ1×σ3 )/2
d) (σ3 – σ1 )/2

Explanation: The maximum shear stress τmax is equal to (σ1 – σ3)/2 which occurs on planes with α= 45°.

9. The normal stresses acting on planes of the soil are known as _____________
a) Major principal stresses
b) Principal stresses
c) Minor principal stresses
d) Principal planes

Explanation: The normal stresses acting on principal planes are called the principal stresses.

10. Stress component on planes of a loaded soil mass depends upon ____________
a) Stress acting on plane
b) Direction of plane
c) Shearing resistance
d) All of the mentioned

Explanation: Through a point in a loaded soil mass, innumerable planes passes and stress component on each plane depends upon the direction of the plane.

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