# Foundation Engineering Questions and Answers – Well Curb, Cutting Edge, Steining and Bottom Plug

This set of Foundation Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Well Curb, Cutting Edge, Steining and Bottom Plug”.

1. The well curb is designed for which of the following purpose?
a) For avoiding skin friction
b) Supporting the weight of well
c) For designing the well
d) All of the mentioned

Explanation: The well curb is designed for supporting the weight of the well with well partial support at the bottom of the cutting edge.

2. Which of the following can be assumed for design purpose of well curb?
a) Three point support of cutting edge
b) Boulders
c) Skin friction
d) Steining

Explanation: A three-point support of the cutting edge resting on a log may be assumed for design purposes of well curb.

3. An effective well curb should withstand ___________
a) Maximum stress
b) Stress due to sand blows
c) Its own weight
d) Blasting

Explanation: The well curb has to withstand stress due to sand blows, as well as due to light blasting required when boulder obstructs the sinking of well.

4. The cutting edge should be provided with an angle of __________
a) 45°
b) 60°
c) 90°
d) 30°

Explanation: The cutting edge should have as sharp an angle of 30° practicable for knifing into the soil without making it too weak to resist the various stresses induced.

5. A sharp vertical edge for the well is provided at _________
a) Inner Face of the well
b) Out of the well
c) Outside face of the caisson
d) All of the mentioned

Explanation: A sharp vertical edge or cutting edge should be provided along the outside face of the caisson or open well.

6. At a given depth, the skin friction of the well is equal to __________
a) Diameter of well
b) μ times the lateral earth pressure
c) Stress condition
d) All of the mentioned

Explanation: The unit skin friction increases with depth, and at a given depth, the skin friction is equal to the coefficient of friction μ times the lateral earth pressure.

7. For loose sand, the value of skin friction is between ________
a) 0.73-2.93
b) 4.9-19.5
c) 1.22-3.42
d) 3.42-6.84

Explanation: For the purpose of design, the values of skin friction given by Terazaghi and peck may be used:
Silt and soft clay: 0.73-2.93 t/m2
Very stiff clay: 4.9-19.5 t/m2
Loose sand: 1.22-3.42 t/m2
Dense sand: 3.42-6.84 t/m2
Dense gravel: 4.9 -9.4 t/m2.

8. Frictional resistance developed during the sinking the well depends on __________
a) Roughness of the surface of contact
b) Diameter of the well
c) Type of soil
d) Lateral earth pressure

Explanation: Frictional resistance depends on the roughness of the surface of contact. For example, a smoothly plastered well steining surface is said to reduce frictional resistance.

9. The skin friction developed in San Francisco Oakland Bay Bridge, was reduced by, which of the following methods?
a) By introducing special equipment
b) By coating smooth oil surface
c) By decreasing the stress developed
d) All of the mentioned

Explanation: In order to reduce the skin friction on the in San Francisco Oakland Bay Bridge, a coating which gave a smooth oily surface that was estimated to reduce the friction between the concrete and fairly clay by 40 %.

10. The bottom plug is designed in _________ shape.
a) Rectangular
b) Mushroom
c) Bowl-shaped
d) Circular

Explanation: The bottom-plug is made in bowl-shaped so as to have inverted arch actions.

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