This set of Geotechnical Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Stress Distribution in the Vicinity of Shafts”.
1. A soil engineers usually encounter problems of stress distribution in __________
a) Vicinity of vertical shafts and Vicinity of inclined shafts
b) Vicinity of horizontal shafts
c) None of the mentioned
d) All of the mentioned
View Answer
Explanation: A soil engineer is commonly encountered with the problem of stress distribution in the vicinity of vertical or inclined shafts in an elastic semi-infinite solid with a horizontal or inclined surface.
2. The problem of stress distribution in the vicinity of shafts was first solved by ________
a) Westergaard
b) Terzaghi
c) Darcy
d) Biot
View Answer
Explanation: In 1940, Westergaard solved the problem of stress distribution by using the theory of plasticity using a suitable stress function.
3. The method given by Biot for solving the problem of stress distribution was based on ________
a) Theory of elasticity
b) Method of superposition
c) Westerngaard method
d) All of the mentioned
View Answer
Explanation: The method suggested by Biot was based on the method of superposition as proposed by Terzaghi in 1943.
4. The stress component which acts on any point in the surrounding material before the excavation of the shaft can be resolved into __________ parts.
a) 3
b) 5
c) 2
d) 4
View Answer
Explanation: i) Stresses due to the weight of material and ii) stress due to pressure exerted by the equivalent liquid are the two stress component that acts at any point on the material.
5. Stress due to equivalent fluid pressure can be found out using __________
a) Biot method
b) Theory of elasticity
c) Lame’s formula
d) Method of superposition
View Answer
Explanation: Stress due to equivalent fluid pressure can be found out by using the Lame’s formula for the state of stress in thick walled cylinder subjected to internal pressure.
6. After excavating the shaft, the shearing stresses along the walls of the shaft will be equal to ___________
a) Zero
b) Normal stress
c) Circumferential stress
d) All of the mentioned
View Answer
Explanation: After the shaft has been excavated the shearing stresses along the walls of the shaft are equal to zero and the radial normal stresses are also equal to zero.
7. When the high value of σϴ in the vicinity of the walls of a shaft exceeds the compressive strength it results in __________
a) Plastic flow of soil
b) Non uniform stress distribution
c) Increase fluid pressure
d) All of the mentioned
View Answer
Explanation: The high value of σϴ in the vicinity of walls of a shaft may exceed the compressive strength of the soil, resulting in a plastic flow of the soil which continues until a state of plastic equilibrium.
8. The stress component at any point, after the excavation of the shaft, will be equal to ____________
a) σR = (σZ)1-(σZ)2
b) σZ = (σZ)1-(σZ)2
c) σϴ = (σϴ)1-(σϴ)2
d) σR = (σR)1-(σR)2
View Answer
Explanation: The stress component at any point, after the excavation of the shaft will be equal to the difference between the initial stresses i.e., σZ = (σZ) 1-(σZ) 2.
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