# Geotechnical Engineering Questions and Answers – Dynamic Analysis of Block Foundations

This set of Geotechnical Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Dynamic Analysis of Block Foundations”.

1. The method of Barken is based on the assumption of ___________
a) Equation of motion
b) Linear spring theory
c) Participation of soil in the vibration
d) All of the mentioned

Explanation: Barken’s method is based on linear spring theory. The method neglects the effect of damping and participating in the soil mass.

2. The rotation of foundation about y axes is known as _____________
a) Yawning
b) Pitching
c) Rocking
d) All of the mentioned

Explanation: In the general case, rotation about y, z and x-axes are respectively known as rocking, yawning and pitching.

3. Barken’s method is used in ___________ places.
a) Congested area
b) Design offices
c) Working area
d) All of the mentioned

Explanation: Barken’s method is very much used in design offices.

4. If the combined C.G. of the machine and foundation lies in the same vertical line, then the twisting modes are _________
a) Coupled
b) Uncoupled
c) All of the mentioned
d) None of the mentioned

Explanation: If the combined C.G. of the machine and foundation lies in the same vertical line as the centroid of the base plane, then the vertical and translation and twisting modes are uncoupled.

5. The value of kx for the elastic support of soil is given by which of the following expression?
a) Kx = Cu A
b) Kx = Cϴ Iy
c) Kx = Cx A
d) Kx = Cu Iy

Explanation: The values of Kx, Ky and Kϴy for the elastic support of soil are given by the following expressions:
For vertical motion: Kz = Cu A
For horizontal motion: Kx = Cx A
For rocking motion: Kϴy: Cϴ Iy.

6. The permissible amplitude should not exceed ___________ for reciprocating machine.
a) Probable amplitude
b) Limiting amplitude
c) Maximum amplitude
d) Minimum amplitude

Explanation: The permissible amplitude should not exceed the limiting amplitude for the machine prescribed by the manufacturers.

7. The methods of Pauw and Balakrishna Rao are based on ___________ assumptions.
a) Equation of motion
b) Linear spring theory
c) Participation of soil in the vibration
d) Barken’s method

Explanation: The method of Pauw and Balakrishna Rao are based on the assumption that a certain mass of soil participates in the vibration with the foundation.

8. According to Barken, the value of the coefficient of elastic uniform shear is taken as __________
a) 0.5
b) 2 Cu
c) 3.0
d) 0.5 Cu

Explanation: According to Barken, the coefficient of elastic uniform shear Cτ for foundation resting on elastic support is taken as 0.5 Cu.

9. If foundation block is supported by an elastic pad of contact area A and thickness t, the value of stiffness factor for vertical motion is given by which of the following expression?
a) Kx = C A/t
b) Kz = E A/t
c) Kϴy = Ely / t
d) All of the mentioned

Explanation: The value of stiffness factors are given by the following expressions:
For vertical motion: Kz = E A /t
For horizontal (sliding motion): Kx = CA /t
For rocking motion: Kϴy = Ely/t.

10. The two natural frequencies representing the couple motion, in sliding and rocking motion is ___________
a) ωn1 and ωn2
b) ωx and ωy
c) ωϴ and ωn
d) ωn1 and ωn

Explanation: ωn1 and ωn2 are the two natural frequencies representing the coupled action (i.e., sliding along x-axis and rocking about the y-axis).

Sanfoundry Global Education & Learning Series – Geotechnical Engineering.

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