Geotechnical Engineering

Dynamic Analysis of Block Foundations

Question 1
Marks : +2 | -2
Pass Ratio : 14%
According to Barken, the value of the coefficient of elastic uniform shear is taken as __________
0.5
2 Cu
3.0
0.5 Cu
Explanation:
According to Barken, the coefficient of elastic uniform shear CÏ„ for foundation resting on elastic support is taken as 0.5 Cu.
Question 2
Marks : +2 | -2
Pass Ratio : 14%
The two natural frequencies representing the couple motion, in sliding and rocking motion is ___________
ωn1 and ωn2
ωx and ωy
ωϴ and ωn
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).
Question 3
Marks : +2 | -2
Pass Ratio : 14%
The rotation of foundation about y axes is known as _____________
Yawning
Pitching
Rocking
All of the mentioned
Explanation:
In the general case, rotation about y, z and x-axes are respectively known as rocking, yawning and pitching.
Question 4
Marks : +2 | -2
Pass Ratio : 29%
The method of Barken is based on the assumption of ___________
Equation of motion
Linear spring theory
Participation of soil in the vibration
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.
Question 5
Marks : +2 | -2
Pass Ratio : 14%
Barken’s method is used in ___________ places.
Congested area
Design offices
Working area
All of the mentioned
Explanation:
Barken’s method is very much used in design offices.
Question 6
Marks : +2 | -2
Pass Ratio : 14%
The methods of Pauw and Balakrishna Rao are based on ___________ assumptions.
Equation of motion
Linear spring theory
Participation of soil in the vibration
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.
Question 7
Marks : +2 | -2
Pass Ratio : 14%
If the combined C.G. of the machine and foundation lies in the same vertical line, then the twisting modes are _________
Coupled
Uncoupled
All of the mentioned
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.
Question 8
Marks : +2 | -2
Pass Ratio : 14%
The value of kx for the elastic support of soil is given by which of the following expression?
Kx = Cu A
Kx = CÏ´ Iy
Kx = Cx A
Kx = Cu Iy
Explanation:
The values of Kx, Ky and KÏ´y for the elastic support of soil are given by the following expressions:
Question 9
Marks : +2 | -2
Pass Ratio : 14%
The permissible amplitude should not exceed ___________ for reciprocating machine.
Probable amplitude
Limiting amplitude
Maximum amplitude
Minimum amplitude
Explanation:
The permissible amplitude should not exceed the limiting amplitude for the machine prescribed by the manufacturers.
Question 10
Marks : +2 | -2
Pass Ratio : 14%
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?
Kx = C A/t
Kz = E A/t
KÏ´y = Ely / t
All of the mentioned
Explanation:
The value of stiffness factors are given by the following expressions: