21. The relationship among specific yield (S_y), specific retention (S_r) and porosity (η ) of an aquifer is

1. 1. S_y = S_r + η

   
   
   

   2. S_y = S_r – η

   
   
   

   3. S_y = η – S_r

   
   
   

   4. S_y = S_r + 2η

   
   
   

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1. View Hint View Answer Discuss in Forum

   Porosity, h = specific yield + specific retention
   = S_y + S_r
   ∴ S_y = η – S_r.

   Correct Option: C

   Porosity, h = specific yield + specific retention
   = S_y + S_r
   ∴ S_y = η – S_r.

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22. Match the following groups
    Group - I
    P Constant head permeability
    Q Consolidation test
    R Pycnometer test
    S Negative skin friction
    Group - II
    1. Pile foundations
    2. Specific gravity
    3. Clay soil
    4. Sand

1. 1. P-4, Q-3, R-2, S-1

   
   
   

   2. P-4, Q-2 R-3, S-1

   
   
   

   3. P-3, Q-4, R-2, S-1

   
   
   

   4. P-4, Q-1, R-2, S-3

   
   
   

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1. View Hint View Answer Discuss in Forum

   P-4, Q-3, R-2, S-1

   Correct Option: A

   P-4, Q-3, R-2, S-1

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23. Four columns of a building are to be located within a plot size of 10 m × 10 m. The expected load on each column is 4000 kN. Allowable bearing capacity of the soil deposit is 100 kN/m². The type of foundation best suited is

1. 1. isolated footing

   
   
   

   2. raft foundation

   
   
   

   3. pile foundation

   
   
   

   4. combined footing

   
   
   

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1. View Hint View Answer Discuss in Forum

   Expected load coming on each column = 4000 KN
   No. of Column = 4
   Total load coming from all column = 4 × 4000
   = 16000 KN
   In raft footing
   Pressure coming to soil
   

   =	P	=	16000
   	A		10 × 10

   
   = 160 KM/m² > 100 KN/m²
   Therefore, pressure acting downwards to soil is more than bearing capacity of soil, so the raft is not provided this condition.
   So, go for pile foundation.

   Correct Option: C

   Expected load coming on each column = 4000 KN
   No. of Column = 4
   Total load coming from all column = 4 × 4000
   = 16000 KN
   In raft footing
   Pressure coming to soil
   

   =	P	=	16000
   	A		10 × 10

   
   = 160 KM/m² > 100 KN/m²
   Therefore, pressure acting downwards to soil is more than bearing capacity of soil, so the raft is not provided this condition.
   So, go for pile foundation.

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24. The degree of disturbance of the sample collected by the sampler is expressed by a term called the “area ratio”. If the outer diameter and inner diameter of the sampler are D₀ and D_i respectively, the area ratio is given by

1. 1. D02 - Di2

      Di2

   
   
   

   2. Di2 - D02

      Di2

   
   
   

   3. D02 - Di2

      D02

   
   
   

   4. Di2 - D02

      D02

   
   
   

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1. View Hint View Answer Discuss in Forum

   D02 - Di2

   Di2

   Correct Option: A

   D02 - Di2

   Di2

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25. The action of negative skin friction on the pile is to

1. 1. increase the ultimate load on the pile

   
   
   

   2. reduce the allowable load on the pile

   
   
   

   3. maintain the working load on the pile

   
   
   

   4. reduce the settlement of the pile

   
   
   

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1. View Hint View Answer Discuss in Forum

   Negative skin friction acts downwards, pulling done the pile.

   Correct Option: B

   Negative skin friction acts downwards, pulling done the pile.

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