Geotechnical Engineering

Shallow Foundations

Question 1
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 2
Marks : +2 | -2
Pass Ratio : 100%
If a maximum settlement of 50 mm is permitted for a raft, the differential settlement must not exceed ___________
30 mm
10 mm
20 mm
25 mm
Explanation:
A raft may undergo large settlement without causing harmful differential settlement. For this reason, almost double settlement of that permitted for footing is acceptable for raft. Therefore if a maximum settlement of 50 mm (2 in) is permitted for a raft, the differential settlement is not likely to exceed 20 mm (0.75 in).
Question 3
Marks : +2 | -2
Pass Ratio : 100%
If the independent spread footing of two columns are connected by a beam, it is called ___________
Combined footing
Trapezoidal combined footing
Strap footing
Raft footing
Explanation:
In strap footing, two independent columns are supported by as trap or beam at the bottom.
Question 4
Marks : +2 | -2
Pass Ratio : 100%
If the resultant of the soil pressure coincides with the resultant of the loads, the soil is pressure is assumed to be ____________
Non-uniformly
Uniformly distributed
Zero
None of the mentioned
Explanation:
If the resultant of the soil pressure coincides with the resultant of the loads and the center of gravity of the footing, the soil pressure is assumed to be uniformly distributed.
Question 5
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 6
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 7
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 8
Marks : +2 | -2
Pass Ratio : 50%
The net pressure can be calculated for raft having width greater than ___________
6 m
20 cm
30 cm
4 m
Explanation:
Based on the settlement criterion for raft, the net pressure can be calculated from the following equation having its width greater than 6m.
Question 9
Marks : +2 | -2
Pass Ratio : 50%
Raft is subdivided in to series of beams to establish __________
Shear failure and Moment diagrams
Pressure distribution
None of the mentioned
All of the mentioned
Explanation:
The raft is subdivided into a series of continuous beams (strips) centered on the appropriate column rows to establish shear failure and moment diagram.
Question 10
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.