Engineering Questions with Answers - Multiple Choice Questions

# Coulomb’s Wedge Theory

1 - Question

The wedge theory of earth pressure is based on the concept of _________
a) Active earth pressure
b) Sliding wedge
c) Wall friction
d) All of the mentioned

Explanation: The wedge theory of earth pressure is based on the concept of a sliding wedge which is torn off from the rest of the backfill on a movement of the wall.

2 - Question

Which of the following is a basic assumption of the wedge theory?
a) The slip surface is plane
b) The backfill is dry
c) The backfill is homogeneous
d) All of the mentioned

Explanation: Based on the assumptions of the wedge theory:
i. The backfill is dry, cohesion less, homogeneous, isotropic, and elastically undeformable.
ii. The slip surface is a plane which passes through the heel of the wall
iii. The sliding wedge itself acts as a rigid body.

3 - Question

The force acting on a wedge of soil are ____________
a) Frictional force
b) Weight of the wedge and Active thrust
c) None of the mentioned
d) All of the mentioned

Explanation: According to wedge theory, the forces acting on a wedge of soil are its weight W, the reaction R along the plane of sliding and the active thrust against the retaining wall.

4 - Question

The active lateral pressure of intact saturated clays is calculated by assuming __________
a) φ=0 and φc=0
b) φ=90
c) None of the mentioned
d) All of the mentioned

Explanation: The active lateral pressure of intact saturated clays for temporary works or immediately after construction of a retaining wall is calculated by assuming φ=φc=0.

5 - Question

The forces acting on the trial wedge which is used for finding Rankine’s active earth pressure is __________
a) Weight W of the wedge
b) Resultant force
c) Resultant reaction between wedge and sol
d) All of the mentioned

Explanation: The three forces acting on a trial wedge are: i) the resultant force that exist between the free body and the wall ii) the weight W of the wedge iii) the resultant reaction between the wedges and the rest of the soil along the surface.

6 - Question

The Rankine’s active earth pressure can also be found out by method of _____________
a) Trial wedges
b) Graphical method
c) Sliding wedge
d) Theoretical calculation

Explanation: The Rankine’s active earth pressure (assuming the wall to be smooth) can be found out by method of trial wedges.

7 - Question

Based on the assumptions of the wedge theory, pressure distribution is assumed to be __________
a) Planar
b) Hydrostatic
c) Equal
d) Distributed

Explanation: The assumption is based on that, the total pressure distribution is hydrostatic,i.e., triangular

8 - Question

In Coulomb’s wedge theory, the angle λ is referred as ___________
a) Angle of wall friction
b) Surcharge angle
c) Critical slip angle
d) None of the mentioned

Explanation: In wedge theory, the angle between the slip plane and the ground is called the critical angle λ.

9 - Question

The φ-line in wedge theory can also be called as __________
a) Surcharge line
b) Natural slope line and Repose line
c) None of the mentioned
d) All of the mentioned

Explanation: The φ-line shows a plane inclined at an angle φ to the horizontal at which the soil is expected to stay in the absence of any lateral support. The line therefore is called the natural slope line or repose line.

10 - Question

In coulomb’s wedge theory, the criterion for maximum active pressure is present at ___________
a) Slip-plane
b) Repose line
c) Surcharge line
d) Ground line