ExamVeda
Login
Home
71
What is the meaning of anisotropic stress in rock mechanics?
Discuss
Answer & Solution
Answer: Option B
Solution:
Anisotropic stress refers to unequal magnitudes of stress acting in different directions, which is common in natural rock environments and affects excavation stability.
72
Which of the following causes time-dependent deformation in rocks?
Discuss
Answer & Solution
Answer: Option C
Solution:
Creep is the time-dependent deformation of materials under constant stress. In rocks, it occurs under high pressure or temperature over long durations.
73
Which factor least affects the strength of a rock joint?
Discuss
Answer & Solution
Answer: Option D
Solution:
Rock color is not a mechanical property and does not influence strength. Water, roughness, and infill significantly affect joint behavior.
74
Which strength parameter is higher in rocks: tensile or compressive?
Discuss
Answer & Solution
Answer: Option C
Solution:
Rocks have much higher compressive strength than tensile strength. Tensile failure occurs more easily due to weaker inter-particle forces in tension.
75
In the Mohr-Coulomb failure criterion, the shear strength of rock is expressed as:
Discuss
Answer & Solution
Answer: Option D
Solution:
The Mohr-Coulomb equation for shear strength is: ? = c + ? tan ?, where:? = shear strengthc = cohesion? = normal stress? = angle of internal friction
76
What is the primary factor influencing the tensile failure in rocks?
Discuss
Answer & Solution
Answer: Option C
Solution:
Microcracks reduce the effective tensile strength in rocks.They act as stress concentrators, initiating failure under low tensile loads.
77
In rock mechanics, dilation angle refers to:
Discuss
Answer & Solution
Answer: Option C
Solution:
The dilation angle is the angle that represents volumetric expansion of rock during shearing.It�s important in stability and tunnel design.
78
A high UCS value indicates:
Discuss
Answer & Solution
Answer: Option C
Solution:
UCS (Uniaxial Compressive Strength) is a key indicator of rock strength.High UCS means the rock can withstand large axial loads.
79
Joint spacing in rock mass affects:
Discuss
Answer & Solution
Answer: Option D
Solution:
Joint spacing determines how the rock mass behaves under load.Closer joints can reduce strength and increase deformability, affecting slope and excavation stability.
80
Which test is most suitable for determining the elastic modulus of rock?
Discuss
Answer & Solution
Answer: Option B
Solution:
The unconfined compression test provides stress-strain data used to compute elastic modulus, which defines stiffness.