Engineering Questions with Answers - Multiple Choice Questions

# Earth Pressure Introduction – 2

1 - Question

In active state, the minor principal stress σ3 is _________
a) horizontal direction
b) vertical direction
c) can be both vertical and horizontal direction
d) in no direction

Explanation: In active state, the minor principal stress denoted by σ3 is in horizontal direction. While in the passive state, the minor principal stress σ3 is in vertical direction.

2 - Question

In passive state, the major principal stress σ1 ____________
a) horizontal direction
b) vertical direction
c) can be both vertical and horizontal direction
d) in no direction

Explanation: In passive state, the minor principal stress denoted by σ3 is in vertical direction. While in the passive state, the major principal stress σ1 is in horizontal direction.

3 - Question

In passive state, the minor principal stress σ3 is _________
a) horizontal direction
b) vertical direction
c) can be both vertical and horizontal direction
d) in no direction

Explanation: In active state, the minor principal stress denoted by σ3 is in horizontal direction. While in the passive state, the minor principal stress σ3 is in vertical direction.

4 - Question

For cohesion-less soil, the ratio of major to minor principal stress is __________
a) σ1σ3=cos2(45°+φ2)
b) σ1σ3=sin2(45°+φ2)
c) σ1σ3=tan2(45°+φ2)
d) σ1σ3=tan2(45°−φ2)

Explanation: The stress condition during plastic equilibrium is given by,
σ1=2ctan(45°+φ2)+σ3tan2(45°+φ2), and for cohesion-less soil, c=0,
∴ σ1σ3=tan2(45°+φ2).

5 - Question

The ratio of horizontal stress σh to vertical stress σv is _______
a) coefficient of earth pressure
b) coefficient of volume change
c) coefficient of compressibility
d) coefficient of consolidation

Explanation: The coefficient of earth pressure is defined as the ratio of The ratio of horizontal stress σh to vertical stress σv.
∴ K=σhσv. Where, K = coefficient of earth pressure.

6 - Question

The coefficient of earth pressure for active state of plastic equilibrium is given by ___________
a) Ka=1tan2(45°+φ2)
b) Ka=tan2(45°+φ2)
c) Ka=sin2(45°+φ2)
d) Ka=1cot2(45°+φ2)

Explanation: For the case of active state, the major principal stress denoted by σ1 is in vertical direction and the minor principal stress σ3 is in horizontal direction.
∴ σ1σ3=σvσh=Ka=1tan2(45°+φ2).

7 - Question

The coefficient of earth pressure for passive state of plastic equilibrium is given by ________
a) Kp=1tan2(45°+φ2)
b) Kp=tan2(45°+φ2)
c) Kp=sin2(45°+φ2)
d) Kp=1cot2(45°+φ2)

Explanation: For the case of passive state, the major principal stress denoted by σ1 is in horizontal direction and the minor principal stress σ3 is in vertical direction.
∴ σ1σ3=σhσv=Kp=tan2(45°+φ2).

8 - Question

The coefficient of earth pressure for active state of plastic equilibrium in terms of sine function is _______
a) Ka=1−sinφ
b) Ka=1−sinφ1+sinφ
c) Ka=1+sinφ1−sinφ
d) Ka=1+sinφ

Explanation: The coefficient of earth pressure for active state of plastic equilibrium is,
Ka=1tan2(45°+φ2),
∴ therefore in terms of sine function,
Ka=1tan2(45°+φ2)=1−sinφ1+sinφ.

9 - Question

The coefficient of earth pressure for passive state of plastic equilibrium in terms of sine function is _______
a) Ka=1−sinφ
b) Ka=1−sinφ1+sinφ
c) Ka=1+sinφ1−sinφ
d) Ka=1+sinφ

Explanation: The coefficient of earth pressure for active state of plastic equilibrium is,
Kp=tan2(45°+φ2),
∴ therefore in terms of sine function,
Kp=tan2(45°+φ2)=1+sinφ1−sinφ.

10 - Question

During the active state of plastic equilibrium, the retaining wall moves _______
a) towards the fill
b) away from the fill
c) does not change its position
d) remains in equilibrium

Explanation: During the active state of plastic equilibrium, the major principal stress denoted by σ1 is in vertical direction and the minor principal stress σ3 is in horizontal direction. Therefore, the movement of the wall will be away from the back fill.

11 - Question

During the passive state of plastic equilibrium, the retaining wall moves _______
a) towards the fill
b) away from the fill
c) does not change its position
d) remains in equilibrium

Explanation: During the passive state of plastic equilibrium, the major principal stress denoted by σ1 is in horizontal direction and the minor principal stress σ3 is in vertical direction. Therefore, the movement of the wall will be towards the back fill.

12 - Question

In active state of plastic equilibrium, the earth pressure on the wall ________
a) increases
b) decreases
c) is zero
d) is constant

Explanation: When the wall moves away from the backfill, mobilization of the internal resistance of the soil takes place in the direction away from the wall. Hence the earth pressure on the wall decreases.

13 - Question

In passive state of plastic equilibrium, the earth pressure on the wall ________
a) increases
b) decreases
c) is zero
d) is constant

Explanation: In passive state of plastic equilibrium, when the wall moves towards the fill, the earth pressure increases because the shearing resistance builds up in the direction of the wall.

14 - Question

In active state, the failure wedge shows ____________
a) downward movement
b) upward movement
c) left side movement
d) right side movement

Explanation: In the active state of plastic equilibrium, the wall moves away from the fill because of the mobilization of the internal resistance of the soil taking place in the direction away from the wall. Due to this the failure wedge shows downward movement.

15 - Question

In passive state, the failure wedge shows ____________
a) downward movement
b) upward movement
c) left side movement
d) right side movement