Geotechnical Engineering Questions and Answers – The Mohr – Colomb Failure Envelope

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This set of Geotechnical Engineering Multiple Choice Questions & Answers (MCQs) focuses on “The Mohr – Colomb Failure Envelope”.

1. The Mohr’s theory of failure can be symbolically expressed as ____________
a) τmax=F(σn) and σmax–σmin = f(σmax +σmin)
b) τmax = σmax– σmin
c) None of the mentioned
d) All of the mentioned
View Answer

Answer: a
Explanation: Mohr’s theory of failure can be symbolically expressed as:
σmax–σmin = f (σmax +σmin) or τmax=f (σn).
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2. The concept of a three dimension yield envelope was presented by _________
a) D.C. Drucker and Prager
b) Mohr
c) None of the mentioned
d) All of the mentioned
View Answer

Answer: a
Explanation: The effect of intermediate principal was studied by D.C. Drucker and W. Prager in 1952, who proposed the concept of a three dimensional yield envelope.

3. A major drawback of Mohr criterion is ____________
a) Shape of the envelope
b) Principal stress
c) Shape of the plane
d) All of the mentioned
View Answer

Answer: a
Explanation: The major drawback of Mohr criterion is that the curved shape of the envelope, hence the functional form of the equation τmax=F (σn) is not amendable to mathematical computation.
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4. The yield or failure criterion can be expressed as ____________
a) f(I1,I2)=0
b) f(I1,I2,I3)=0
c) f(σ1,σ2,σ3)=0
d) f(σmax +σmin)
View Answer

Answer: b
Explanation: The yield criterion may be expressed as f (I1, I2, I3) = 0
Where I1, I2, I3 are the invariant of stress.

5. If the auxiliary plane in hydrostatic axis passes through the origin, then its equation is _____________
a) σ1+σ2+σ3=0
b) σ1+σ2+σ3=constant
c) I1+ I2+I3 =0
d) f(σ1,σ2,σ3)=0
View Answer

Answer: a
Explanation: If the auxiliary plane passes through the origin its equation is σ1+σ2+σ3=0 and equation will be σ1+σ2+σ3=constant if the plane is perpendicular to the hydrostatic axis.
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6. The intersection of the yield surface or envelope with octahedral plane is called ____________
a) Yield point
b) Deviation point
c) Failure locus
d) Space diagonal
View Answer

Answer: c
Explanation: The intersection of yield surface with octahedral plane is called the failure locus. A point on the failure locus represents the stress state at incipient failure.

7. The hydrostatic pressure’s inability to produce failure under normal pressure was first demonstrated by ___________
a) Cross land
b) W. Pager
c) D.C. Drucker
d) Mohr
View Answer

Answer: a
Explanation: Experiments conducted by Cross land in 1965 have demonstrated that a pure state of hydrostatic pressure is unable to produce failure even under enormous pressure.
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8. Which of the following equation represent hydrostatic pressure in its purest form?
a) σ1+σ2+σ3=0
b) σ1+σ2+σ3=constant
c) σ1=σ2=σ3
d) σmax+ σmin
View Answer

Answer: c
Explanation: According to cross land σ1=σ2=σ3 represent hydrostatic pressure in its purest form.

9. The Mohr-Coulomb criterion assumes that the strength of the soil is independent of ____________
a) σ1
b) σ2
c) σ3
d) All of the mentioned
View Answer

Answer: b
Explanation: The Mohr-Coulomb criterion implicitly assumes that the strength is independent of the intermediate principal stress σ2.
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10. The auxiliary plane in the hydrostatic axis can also be called as ___________
a) Failure plane
b) Octahedral plane
c) Deviatoric plane
d) Principal plane
View Answer

Answer: c
Explanation: Since all the points in the auxiliary plane represent deviatorial state of stress, the plane is also called the deviatoric plane.

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Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He is Linux Kernel Developer & SAN Architect and is passionate about competency developments in these areas. He lives in Bangalore and delivers focused training sessions to IT professionals in Linux Kernel, Linux Debugging, Linux Device Drivers, Linux Networking, Linux Storage, Advanced C Programming, SAN Storage Technologies, SCSI Internals & Storage Protocols such as iSCSI & Fiber Channel. Stay connected with him @ LinkedIn | Youtube | Instagram | Facebook | Twitter