Foundation Engineering Questions and Answers Part-16

1. In Swedish circle method ___________ analysis cases are considered.
a) φC = 0
b) C – φ and φu = 0
c) None of the mentioned
d) All of the mentioned

Answer: b
Explanation: In Swedish slip circle method two cases are considered: i) analysis of purely cohesive soil (φu = 0) and ii) analysis of a soil possessing both cohesion and friction (C-φ analysis).

2. When does the critical condition of d/s slope, occur in reservoir?
a) Reservoir is full
b) Pore pressure is high
c) Steady seepage does not occur
d) All of the mentioned

Answer: a
Explanation: Critical condition of d/s slope occurs when the reservoir is full and percolation is at its maximum rate.

3. In the rectangular plot method if there are n-slices, the total number of ordinates will be ____________
a) n – 1
b) n
c) n – 2
d) None of the mentioned

Answer: a
Explanation: In the rectangular plot method if there are n-slices, the total number of ordinates will be (n-1), the ordinates at the end of the last strip being zero.

4. Stability of slopes of an earth dam is tested under, which of the following condition?
a) Stability of downstream slope during steady seepage and Stability of upstream slope during a sudden drawdown
b) Stability of upstream slope during sudden seepage
c) None of the mentioned
d) All of the mentioned

Answer: a
Explanation: The stability of slopes of an earth dam is tested under the following conditions:
i) Stability of downstream slope during steady seepage
ii) Stability of upstream slope during a sudden drawdown
iii) Stability of upstream and downstream slopes during and immediately after construction.

5. When a dam is built of impervious compressible soil, water is entrapped in the pore space due to ___________
a) Excessive pore pressure
b) Volume change in the soil mass
c) Low shear strength of soil
d) Unstable soil mass

Answer: b
Explanation: When a dam is built of relatively impervious compressible soil, excess pore pressure develops in the air and water entrapped in the pore pressure. This is because the soil mass undergoes a change in the soil due to compaction of the dam construction and also due to a down weight.

6. The area of U-diagram in finding stability of D/S slope during steady seepage, can be measured by ___________
a) Planimeter and Rectangular plot method
b) Fellinious method
c) None of the mentioned
d) All of the mentioned

Answer: a
Explanation: The area of U-diagram can be measured with the help of a planimeter, or else the rectangular plot method can be utilized

7. The magnitude and distribution of pore water pressure on a slip surface can be calculated from ___________
a) Pressure net
b) Test data
c) Graphical method
d) Rectangular plot method

Answer: a
Explanation: The magnitude and distribution of pore water pressure on a likely slip surface is estimated from pressure net which are developed from the flow net.

8. The pore water pressure at any point on the slip surface is represented by ____________
a) Piezometric head
b) Pore pressure
c) Factor of safety
d) Failure plane

Answer: a
Explanation: The pore water pressure at any point is represented by the piezometric head hw at that point.

9. The estimation of construction pore pressure can be made with the help of ___________
a) Swedish circle method
b) Bishop’s method
c) Hilf’s equation
d) Rectangular plot method

Answer: c
Explanation: The estimation of the construction pore pressure is made with the help of Hilf’s equation:
u = pa Δ / (va + hc γw – Δ).

10. In Hilf’s equation ‘u = pa Δ / (va + hc γw – Δ)’, hc refers to __________
a) Induced pore pressure
b) Henry’s constant
c) Volume of pore water
d) Volume of air voids

Answer: b
Explanation: In Hilf’s equation hc refers to Henry’s constant of solubility of air in water by volume (= 0.02 at 68°F).