Geotechnical Engineering

Shallow Foundations

Question 1
Marks : +2 | -2
Pass Ratio : 100%
When the allowable soil is low or the building loads are heavy, the footing used is ___________
Raft footing
Strap footing
Trapezoidal combined footing
Rectangular combined footing
Explanation:
When the allowable soil pressure is low, or the building loads are heavy, the use of spread footings would cover more than one-half of the area and it may prove more economical to use mat or raft foundation.
Question 2
Marks : +2 | -2
Pass Ratio : 100%
The foundation that is used when the soil mass is sufficiently erratic?
Strap footing
Combined footing
Mat footing
Rectangular combined footing
Explanation:
Mat footing is used where the soil contains compressible lenses or the soil is sufficiently erratic so that the differential settlement would be difficult to control.
Question 3
Marks : +2 | -2
Pass Ratio : 50%
If the penetration resistance N is less than 5, which of the following measures can be adopted?
Using piles and piers and Compacting sand
Using inverted flat slab
None of the mentioned
All of the mentioned
Explanation:
If N is less than 5, sand should be compacted by artificial means to rise N above 10, or else piles or piers should be used.
Question 4
Marks : +2 | -2
Pass Ratio : 100%
The penetration resistance N for designing of raft should be taken at ___________ intervals.
50 cm
60 cm
75 cm
20 cm
Explanation:
The penetration resistance N values should be taken at 75 cm intervals for a depth equal to width of the raft, below the base of the raft.
Question 5
Marks : +2 | -2
Pass Ratio : 50%
In designing rectangular combined footing _________ should be adopted as the design value.
Stress distribution
Compression index
Maximum bending moment
Safe bearing pressure
Explanation:
The maximum bending moment should be adopted as the design value for the reinforced concrete rectangular footing, which should also be checked for maximum shear and bond etc.
Question 6
Marks : +2 | -2
Pass Ratio : 100%
The net ultimate bearing capacity for raft may be determined by __________
Skempton’s equation and Terzaghi’s equation
Darcy’s equation
None of the mentioned
All of the mentioned
Explanation:
The net ultimate bearing capacity may be determined from both Skempton and Terzaghi’s equation as given below:
Question 7
Marks : +2 | -2
Pass Ratio : 100%
In raft footing, if the C.G of the load coincide with the centroid of the raft, the upward load is considered as ___________
Non uniform pressure
Uniform pressure
Excess pressure
None of the mentioned
Explanation:
If the Center of gravity of the load coincides with the centroid of the raft, the upward load is regarded as a uniform pressure, which will be equal to the downward load divided by the area of the raft.
Question 8
Marks : +2 | -2
Pass Ratio : 100%
Which of the following condition is true regarding the transfer of load from strap to soil, used in strap footing?
Transfer load to soil
Does not transfer load to soil
Partially transfer to load
None of the mentioned
Explanation:
The strap used does not remain in contact with soil, and thus does not transfer any pressure to the soil.
Question 9
Marks : +2 | -2
Pass Ratio : 100%
For a rectangular combined footing, xÌ… is given as ___________
xÌ… = L/2
L/3 < xÌ… < L/2
xÌ… = L/3
None of the mentioned
Explanation:
For a rectangular combined footing, xÌ… = L/2 and for a trapezoidal combined footing solutions lies between the limits L/3 < xÌ… < L/2.
Question 10
Marks : +2 | -2
Pass Ratio : 50%
What will be the shape of footing if a=0, is substituted in the pressure intensity equation “q2 = a. qs”?
Rectangular
Triangular
Trapezoidal
Circular
Explanation:
In the pressure intensity equation q2 = a. qs, if a= 0 we have a triangle with xÌ… = L/3.