Foundation Engineering Questions and Answers Part-17

1. In the friction circle method, it is assumed that the resultant reaction is ___________ to the friction circle.
a) Perpendicular
b) Tangential
c) Parallel
d) None of the mentioned

Answer: c
Explanation: In the friction circle method, it is assumed that the resultant reaction is tangential in the friction circle, since the error involved in this assumption is of small magnitude

2. The friction circle may be also referred as __________
a) φ-circle
b) Plane circle
c) Cohesion circle
d) All of the mentioned

Answer: a
Explanation: The friction circle having radius r sin φ is also called as φ-circle.

3. A circle is considered to be a critical slip circle, if it has ___________
a) Maximum factor of safety
b) Minimum factor of safety
c) Maximum radius
d) All of the mentioned

Answer: b
Explanation: The circle giving minimum factor of safety Fc is considered as a critical slip circle

4. The factor of safety with respect to cohesion is given by the equation ____________
a) FC = HC / H
b) FC = C / Cm
c) FC = τf / τ
d) All of the mentioned

Answer: b
Explanation: The factor of safety Fc with respect to cohesive strength, based on the assumption that the frictional strength has been fully mobilized, is given by
FC = C / Cm.

5. The friction circle method assumes the failure surface as ___________
a) Cycloid
b) Curve
c) Arc of circle
d) None of the mentioned

Answer: c
Explanation: Similar to Culmann’s method, the friction circle method also assumes the failure surface as the arc of circle.

6. The forces acting on a sliding wedge are ___________
a) Weight of the wedge
b) Total frictional force
c) Total cohesive resistance
d) All of the mentioned

Answer: d
Explanation: The forces acting on a sliding wedge are i) the weight of the wedge ii) the total frictional resistance or resultant, and iii) total cohesive resistance along the slip circle.

7. The factor of safety Fc with respect to cohesive strength is based on the assumption that ___________
a) Frictional force is fully mobilized
b) Frictional force is zero
c) Total cohesive resistance is zero
d) All of the mentioned

Answer: a
Explanation: The factor of safety with respect to cohesive strength, based on the assumption that frictional force has been fully mobilized, and the equation is given by FC = C / Cm

8. The factor K, in the radius of the friction circle(Kr sin φ) depends on ____________
a) Radius of the frictional circle
b) Frictional resistances offered
c) Cohesive resistance
d) Central angle of the slip arc

Answer: d
Explanation: In the frictional circle radius of Kr sin φ, the factor K depends on the central angle δ of the slip arc

9. The gross pressure intensity (q) of a structure is ___________
a) Total pressure at base of the footing
b) Excess pressure after the construction of the structure
c) Minimum pressure intensity at the base
d) None of the mentioned

Answer: a
Explanation: The gross pressure intensity q is the total pressure at the base of the footing due to the weight of the superstructure.

10. The ultimate bearing capacity and the net ultimate capacity are connected by the relation ____________
a) qf = qnf +/- σ̅ and qf = qf – σ̅
b) qf = qnf – σ̅
c) None of the mentioned
d) All of the mentioned

Answer: a
Explanation: The ultimate bearing capacity qf and the net ultimate capacity are connected by the following relation:
qf = qnf + σ̅ (or) qf = qf – σ̅
where σ̅ is the effective surcharge at the base level of the foundation.