Soil Mechanics and Foundation Sheet 21

1) Question.

According to Coulomb's law, the shearing strength of soil is

[c= Cohesion (apparent or actual), p= Normal stress on the plane of shear, $ϕ$ = Angle of internal friction or angle of shearing resistance]
Answer.
- 1
  
  $c - p \tan ϕ$
- 2
  
  $p - c \tan ϕ$
- 3
  
  $c + p \tan ϕ$
- 4
  
  $p + c \tan ϕ$
Answer: 3

Explanation:
2) Question.

The angle of shearing resistance for dry loose sand is same as that of angle of internal friction.
Answer.
- 1
  
  Right
- 2
  
  Wrong.
Answer: 1

Explanation:
3) Question.

The angle of internal friction of round-grained dense sand is about
Answer.
- 1
  
  $5^{0} t o 25^{0}$
- 2
  
  $25^{0} t o 30^{0}$
- 3
  
  $30^{0} t o 35^{0}$
- 4
  
  $32^{0} t o 37^{0}$
Answer: 4

Explanation:
4) Question.

The angle of internal friction of round-grained loose sand is about
Answer.
- 1
  
  $5^{0} t o 25^{0}$
- 2
  
  $25^{0} t o 30^{0}$
- 3
  
  $30^{0} t o 35^{0}$
- 4
  
  $32^{0} t o 37^{0}$
Answer: 2

Explanation:
5) Question.

Which one of the following parameters can be used to estimate the angle of friction of a sandy soil ?
Answer.
- 1
  
  Particle size
- 2
  
  Roughness of particle
- 3
  
  Density index
- 4
  
  Particle size distribution
Answer: 3

Explanation:
6) Question.

The settlement of a footing in clays $(S_{F})$ is given by
Answer.
- 1
  
  $\frac{S_{P}}{B_{P}} \times B_{F}$
- 2
  
  $\frac{S_{P}}{B_{F}} \times B_{F}$
- 3
  
  $\frac{S_{P}}{{[\frac{B_{P} (B_{F +} 30.48)}{B_{F} (B_{P} + 30.48)}]}^{2}}$
- 4
  
  $\frac{S_{P} {(B_{P} + 30.48)}^{2}}{{(B_{F +} 30.48)}^{2}}$
Answer: 1

Explanation:
7) Question.

If the pressure on a clay layer increases slightly from p to p+ $δ$ p and the void ratio decreases from $e_{0}$ to e, then the coefficient of compressibility is given by
Answer.
- 1
  
  e/p
- 2
  
  $\frac{e_{0}}{δ p}$
- 3
  
  $\frac{e}{δ p}$
- 4
  
  $\frac{e_{0} - e}{δ p}$
Answer: 4

Explanation:
8) Question.

The unit of coefficient of compressibility is inverse of pressure.
Answer.
- 1
  
  Correct
- 2
  
  Incorrect.
Answer: 1

Explanation:
9) Question.

The coefficient of compressibility..... with increase in pressure.
Answer.
- 1
  
  increases
- 2
  
  decreases
- 3
  
  does not change
Answer: 2

Explanation:
10) Question.

The coefficient of volume of compressibility is given by

[ $a_{v}$ = Coefficient of compressibility, $e_{0}$ = Void ratio]
Answer.
- 1
  
  $\frac{a_{v}}{1 + e_{0}}$
- 2
  
  $\frac{1 + e_{0}}{a_{v}}$
- 3
  
  $\frac{e_{0}}{a_{v}}$
- 4
  
  $\frac{e_{0}}{a_{0}}$
Answer: 1

Explanation:
11) Question.

A 300 mm square bearing plate settles by 15 mm in a plate load test on a cohesive soil when the intensity of loading is $0.2 N / m m^{2}$ . The settlement of a prototype shallow footing 1 m square under the same intensity of loading is
Answer.
- 1
  
  15 mm
- 2
  
  30 mm
- 3
  
  50 mm
- 4
  
  167 mm
Answer: 3

Explanation:
12) Question.

A 600 mm square bearing plate settles by 15 mm in plate load test on cohesionless soil under an intensity of loading of $0.2 N / m m^{2}$ . The settlement of a prototype shallow footing 1 m square under the same intensity of loading is
Answer.
- 1
  
  15 mm
- 2
  
  between 15 mm and 25 mm
- 3
  
  25 mm
- 4
  
  greater than 25 mm
Answer: 2

Explanation:
13) Question.

The rise of water table below the foundation influences the bearing capacity of soil mainly by reducing
Answer.
- 1
  
  cohesion and effective angle of shearing resistance
- 2
  
  cohesion and effective unit weight of soil
- 3
  
  effective unit weight of soil and effective angle of shearing resistance
- 4
  
  effective angle of shearing resistance
Answer: 2

Explanation:
14) Question.

The net ultimate bearing capacity of a purely cohesive soil
Answer.
- 1
  
  depends on width of footing and is independent of depth of footing
- 2
  
  depends on depth of footing and is independent of width of footing
- 3
  
  depends on both depth and width of footing
- 4
  
  is independent of both depth and width of footing
Answer: 4

Explanation:
15) Question.

According to Terzaghi's theory, the ultimate bearing capacity at ground surface for a purely cohesive soil and for a smooth base of a strip footing is

where C = unit cohesion of soil
Answer.
- 1
  
  2.57 C
- 2
  
  5.14 C
- 3
  
  5.7 C
- 4
  
  6.2 C
Answer: 2

Explanation:
16) Question.

Base failure of a finite slope
Answer.
- 1
  
  occurs when soil below the level of toe is strong
- 2
  
  occurs when there is a relatively weak zone in upper part of the slope
- 3
  
  occurs when the soil below the toe is relatively soft and weak
- 4
  
  is a most common failure and occurs in relatively steep slopes
Answer: 3

Explanation:
17) Question.

A cylindrical specimen of saturated soil failed under an axial vertical stress of $100 k N^{2} / m^{2}$ when it was laterally unconfined. The failure plane was inclined to the horizontal plane at an angle of $45^{o}$ . The values of cohesion and angle of internal friction for the soil are respectively
Answer.
- 1
  
  $0.5 N / m m^{2} a n d 30^{o}$
- 2
  
  $0.05 N / m m^{2} a n d 0^{o}$
- 3
  
  $0.2 N / m m^{2} a n d 0^{o}$
- 4
  
  $0.05 N / m m^{2} a n d 45^{o}$
Answer: 2

Explanation:
18) Question.

In a deposit of normally consolidated clay
Answer.
- 1
  
  effective stress increases with depth but water content of soil and undrained strength decrease with depth
- 2
  
  effective stress and water content increase with depth but undrained strength decreases with depth
- 3
  
  effective stress and undrained strenth increase with depth but water content decreases with depth
- 4
  
  effective stress, water content and undrained strenth decrease with depth
Answer: 3

Explanation:
19) Question.

Shear strength of aoil is a unique function of
Answer.
- 1
  
  effective stress only
- 2
  
  total stress only
- 3
  
  both effective stress and total stress
- 4
  
  none of the above
Answer: 1

Explanation:
20) Question.

Skempton's pore pressure coefficient B for saturated soil is
Answer.
- 1
  
  1
- 2
  
  zero
- 3
  
  between 0 and 1
- 4
  
  greater than 1
Answer: 1

Explanation:

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