Soil Mechanics and Foundation Sheet 18

1) Question.

The coefficient of volume compressibility is
Answer.
- 1
  
  directly proportional to the void ratio
- 2
  
  inversely proportional to the void ratio
- 3
  
  directly proportional to the coefficient of compressibility
- 4
  
  inversely proportional to the coefficient of compressibility
Answer: 3

Explanation:
2) Question.

The change in volume of soil per unit of initial volume due to a given unit increase in pressure is called
Answer.
- 1
  
  coefficient of permeability
- 2
  
  coefficient of compressibility
- 3
  
  coefficient of volume compressibility
- 4
  
  coefficient of curvature
Answer: 3

Explanation:
3) Question.

The coefficient of consolidation of a soil is affected by
Answer.
- 1
  
  compressibility
- 2
  
  permeability
- 3
  
  both (a) and (b)
- 4
  
  none of these
Answer: 3

Explanation:
4) Question.

The contact pressure of rigid footing on cohesive soils is
Answer.
- 1
  
  more in the centre than at the edges
- 2
  
  less in the centre than at the edges
- 3
  
  uniform throughout
- 4
  
  none of these
Answer: 2

Explanation:
5) Question.

The contact pressure of flexible footing on non-cohesive soils is
Answer.
- 1
  
  more in the centre than at the edges
- 2
  
  less in the centre than at the edges
- 3
  
  uniform throughout
- 4
  
  none of these
Answer: 1

Explanation:
6) Question.

The process of obtaining increased density of soil in a fill by reduction of its pore space by the expulsion of air, is known as
Answer.
- 1
  
  soil exploration
- 2
  
  soil stabilisation
- 3
  
  soil compaction
- 4
  
  consolidation
Answer: 3

Explanation:
7) Question.

The process of maintaining or improving the performance of a soil as a constructional material, usually by the use of admixtures, is known as
Answer.
- 1
  
  soil exploration
- 2
  
  soil stabilisation
- 3
  
  soil compaction
- 4
  
  consolidation
Answer: 2

Explanation:
8) Question.

The high density of the soil placed in a fill is desired in order to
Answer.
- 1
  
  increase its shear resistance
- 2
  
  reduce future settlements
- 3
  
  reduce percolation through the fill
- 4
  
  all of these
Answer: 4

Explanation:
9) Question.

The critical height in the stability of soil is the
Answer.
- 1
  
  minimum height at which it is possible for the sloped bank of soil to be stable
- 2
  
  maximum height at which it is possible for the sloped bank of soil to be stable
- 3
  
  minimum vertical height of the soil is an open excavation
- 4
  
  maximum vertical height of the soil is an open excavation.
Answer: 2

Explanation:
10) Question.

In case of coarse grained sand having high permeability and low plasticity, 95% of consolidation occurs within....... after application of load.
Answer.
- 1
  
  1 minute
- 2
  
  30 minutes
- 3
  
  1 hour
- 4
  
  2 hour
Answer: 1

Explanation:
11) Question.

For a base failure, the depth factor $D_{f}$ is
Answer.
- 1
  
  zero
- 2
  
  1
- 3
  
  $0 < D_{f} < 1$
- 4
  
  $D_{f} > 1$
Answer: 4

Explanation:
12) Question.

Taylor's stability number is equal to

where C= unit cohesion

$F_{c}$ = factor of safety with respect to cohesion

y= unit weight of soil

$H_{c}$ = critical height

H= actual height
Answer.
- 1
  
  $\frac{C}{F_{c} H}$
- 2
  
  $\frac{C}{F_{c} y H_{c}}$
- 3
  
  $\frac{C}{y H}$
- 4
  
  $\frac{C}{y H_{c}}$
Answer: 4

Explanation:
13) Question.

The critical height of an unsupported vertical cut in a cohesive soil is given by

Where C= unit cohesion

$ϕ$ = angle of internal friction

$γ$ = unit weight of soil
Answer.
- 1
  
  $\frac{4 C}{γ} \tan (45^{o} + \frac{ϕ}{2})$
- 2
  
  $\frac{2 C}{γ} \tan (45^{o} + \frac{ϕ}{2})$
- 3
  
  $\frac{4 C}{γ} c o t (45^{o} + \frac{ϕ}{2})$
- 4
  
  $\frac{2 C}{γ} c o t (45^{o} + \frac{ϕ}{2})$
Answer: 1

Explanation:
14) Question.

A retaining wall 6m high supports a bakfill with a surharge angle of $10^{o}$ . The back of the wall is inclined to the vertical at a positive batter angle of $5^{o}$ . If the angle of wall friction is $7^{o}$ ,then the resultant active earth pressure will act at a distance of 2 m above the base and inclined to the horizontal at an angle of
Answer.
- 1
  
  $7^{o}$
- 2
  
  $10^{o}$
- 3
  
  $12^{o}$
- 4
  
  $17^{o}$
Answer: 3

Explanation:
15) Question.

Passive earth pressure in a soil mass is proportional to

where $μ$ is Poission's ratio and $ϕ$ is the effective angle of internal friction of soil.
Answer.
- 1
  
  $\tan^{2} (45^{o} + \frac{ϕ}{2})$
- 2
  
  $\frac{μ}{(1 - μ)}$
- 3
  
  $\tan^{2} (45^{o} - \frac{ϕ}{2})$
- 4
  
  $c o t^{2} (45^{o} + \frac{ϕ}{2})$
Answer: 1

Explanation:
16) Question.

The coefficient of active earth pressure for a loose sand having an angle of internal friction of $30^{o}$ is
Answer.
- 1
  
  1/3
- 2
  
  3
- 3
  
  1
- 4
  
  1/2
Answer: 1

Explanation:
17) Question.

The angle that Coulomb's failure envelope makes with the horizontal is called
Answer.
- 1
  
  cohesion
- 2
  
  angle of internal friction
- 3
  
  angle of repose
- 4
  
  none of the above
Answer: 2

Explanation:
18) Question.

In an unconfined compression test on a cly specimen of initial volume V and length L, the area of cross-section at failure is taken as

where $∆ L$ is the change in lenth and $∆ V$ is change in volume
Answer.
- 1
  
  $\frac{V}{L - ∆ L}$
- 2
  
  $\frac{V + ∆ V}{L - ∆ L}$
- 3
  
  $\frac{V - ∆ V}{L - ∆ L}$
- 4
  
  $\frac{V}{L + ∆ L}$
Answer: 1

Explanation:
19) Question.

Unconfined compressive strenth test is
Answer.
- 1
  
  undrained test
- 2
  
  drained test
- 3
  
  consolidated undrained test
- 4
  
  consolidated drained test
Answer: 1

Explanation:
20) Question.

Select the incorrect statement

Effective angle of shearing resistance
Answer.
- 1
  
  increases as the size of particles increases
- 2
  
  increases as the soil gradation improves
- 3
  
  is limited to a maximum value of $45^{o}$
- 4
  
  is rarely more than $30^{o}$ for fine grained soil
Answer: 3

Explanation:

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