Geotechnical Engineering

Machine Foundations

Question 1
Marks : +2 | -2
Pass Ratio : 20%
The size of co-vibrating body of soil depends on _________
Soil mass
Apparent soil mass
Transmitted force
Size of the base area
Explanation:
The size of co-vibrating body of soil depends on frequency and is influenced by the size of the base area of the vibrator and by the elastic properties of the soil.
Question 2
Marks : +2 | -2
Pass Ratio : 20%
The equation for natural frequency of system as suggested by Barken is __________
ωn = √f(1 – r2)
ωn = √cu A / m
ωn = cu A / m
None of the mentioned
Explanation:
Barken suggested the following equation for the natural frequency of the system
Question 3
Marks : +2 | -2
Pass Ratio : 20%
An aim of the foundation designer should be such that the frequency ratio f/fn is either less than _________
1.5
0.6
2.0
3.4
Explanation:
The aim of the designer should be such that the frequency ratio f/fn is either less than 0.6 or more than 1.5 by suitably proportioning it.
Question 4
Marks : +2 | -2
Pass Ratio : 20%
What are the methods for determining the natural frequency of the foundation of soil system?
Barken’s method and Rankine’s method
Pauw’s method
None of the mentioned
All of the mentioned
Explanation:
The three methods of determining the natural frequency of the foundation soil system are: i) Barken’s method ii) Balakrishna Rao’s method iii) Pauw’s method.
Question 5
Marks : +2 | -2
Pass Ratio : 20%
In a damped force vibratory system, the support is derived by _______
Co-vibrating body
Spring mass system
Transmitting force
Soil mass
Explanation:
In a damped force vibratory system, the support is derived from the foundation by way of transmitting a force (FT) to the foundation.
Question 6
Marks : +2 | -2
Pass Ratio : 20%
On calculating the natural frequency of the system, Barken did not take into account of __________
Contact area
Frequency ratio
Mass of the vibrating soil
Mass of machine
Explanation:
The formula suggested by Barken for natural frequency does not take into account of the mass of soil vibrating with the foundations.
Question 7
Marks : +2 | -2
Pass Ratio : 20%
The co-efficient of elastic uniform compression of soil depends on which of the following factor?
Size of area of foundation
Mass of foundation
Exciting force
All of the mentioned
Explanation:
The coefficient of elastic uniform compression of soil depends not only on elastic constant E and μ but also on the size of the base contact area of foundation.
Question 8
Marks : +2 | -2
Pass Ratio : 20%
The bulb of pressure concept for calculating the apparent mass of soil was introduced by _________
Balakrishna and Nag raj
Barken
None of the mentioned
All of the mentioned
Explanation:
In 1960, Balakrishna and Nag raj proposed the bulb of pressure concept of calculating the apparent mass of soil participating in the vibration.
Question 9
Marks : +2 | -2
Pass Ratio : 20%
Recommended design value for permissible load on soil under the action of static load, for rock type soil group is ________
Greater than 10
5-10
3.5-5
Greater than 5
Explanation:
The recommended design value of the co-efficient of elastic uniform compression for permissible load on soil under action of static load only is greater than 5 kg/cm2.
Question 10
Marks : +2 | -2
Pass Ratio : 40%
The mass of co-vibrating soil is called __________
Weight of vibrator
Soil mass
Apparent soil mass
Certain soil mass
Explanation:
The mass of co-vibrating soil is called the apparent soil mass ms, participating in the vibrations.