Engineering Questions with Answers - Multiple Choice Questions

# Plastic Equilibrium in Soils : Active and Passive States

1 - Question

The theory of plasticity pertaining to soils is based on ___________
a) Mohr’s theory
b) Rankine’s method
c) Mohr-coulomb theory
d) None of the mentioned

Explanation: The theory of plasticity pertaining to soils is based on Mohr’s theory of rupture.

2 - Question

On designing retaining walls it is necessary to take care of __________ exerted by soil mass.
a) Erosion
b) Lateral pressure
c) Surcharge
d) Lateral stress

Explanation: In the designing of retaining walls; sheet piles or other earth-retaining structures, it is necessary to compute the lateral pressure exerted by the retained mass of soil.

3 - Question

The material retained or supported by the retaining structure is called __________
a) Surcharge
b) Support wall
c) Back fill
d) All of the mentioned

Explanation: The material retained or supported by the structure is called backfill which may have its top surface horizontal or inclined.

4 - Question

The coefficient of earth pressure when the soil is at equilibrium is ___________
a) σv /σh
b) σh /σv
c) σv × σh
d) σ1 / σ3

Explanation: When the soil is at elastic equilibrium(i.e. at rest) the ratio of horizontal to vertical stress is called the co-efficient of earth pressure of rest.
σh /σv = K0.

5 - Question

The computation of stress in plastic equilibrium is based on __________
a) Theory of plasticity
b) Mohr’s theory of rupture
c) Rankine’s theory
d) All of the mentioned

Explanation: The theory on which the computation of the stress in a state of plastic equilibrium is based is called the theory of plasticity.

6 - Question

The wedge-shaped portion of the backfill tending to move with the wall is called _______
a) Wedge fall
b) Active fall
c) Failure wedge
d) None of the mentioned

Explanation: During the active state, the wall moves away from backfill and a certain portion of the backfill in wedged-shaped tend to move which is called a failure wedge.

7 - Question

In active stress, the major principal stress σ1 acting on the wall will be in __________ plane.
a) Vertical
b) Horizontal
c) Inclined
d) Zero

Explanation: In an active state, the major principal stress σ1 is vertical and the minor principal stress σ3 is horizontal.

8 - Question

The plastic state of stress was proposed by ___________
a) Mohr
b) Rankine
c) Coulomb
d) Darcy

Explanation: The plastic state of stress when the failure is imminent was investigated by Rankine in 1860.

9 - Question

The position of the backfill lying above the horizontal plane at the top of wall is called _________
a) Active state
b) Plasticity
c) Surcharge
d) Slip lines

Explanation: The position of the backfill lying above a horizontal plane at the elevation of the top of a wall is called the surcharge, and its inclination to the horizontal is called surcharge angle β.

10 - Question

What will be the co-efficient of passive earth pressure, at a depth of 8m in cohesion less soil sand with an angle of internal friction of 30° when the water rises to the ground level?
a) 4
b) 5
c) 3
d) 1