REVIEW INNOVATIONS

MANILA – CEBU - DAVAO

PHILIPPINES

CIVIL ENGINEERS First Pre-board Examination

Sunday, February 9, 2024 1:00 p.m. — 3:00 p.m.
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HYDRAULICS AND GEOTECHNICAL ENGINEERING SET A

INSTRUCTION: Select the correct answer for each of the following questions.
Mark only one answer for each item by shading the box corresponding to the
letter of your choice on the answer sheet provided. STRICTLY NO ERASURES
ALLOWED.GOOD LUCK.

NOTE: A times B is represented by A × B or A*B. A raised to the power n is

expressed as A^n. All problems are 1 point each.

1. A mercury barometer at the base of the mountain reads 620 mm. At the same
time another barometer at the top of the mountain reads 450 mm. Assuming
weight of air to be constant at 10 N/m3, what is the height of the
mountain, in meters?
A. 2468 C. 2268
B. 2368 D. 2168

2. A mercury barometer at the base of the mountain reads 660 mm. What would
be the corresponding reading in water barometer, in meters?
A. 8.976 C. 7.689
B. 9.768 D. 6.879

3. A square pole (s.g.=0.68), 80 mm by 80 mm by 6 m long, is suspended by a

wire so that 4 m is submerged in water and 2 m is above the surface. What
is the tension (N) in the wire?
A. 5 C. 6
B. 4 D. 3

Situation 1. An embankment was constructed with a clayey soil at a moisture

content of 12%. Just after construction, the degree of saturation of the
soil was found to be 55%. The soil absorbed water during the monsoon and
its degree of saturation increased to 90%. Assume Gs = 2.68

4. Determine the water content of the soil at this stage

A. 18.2% C. 22.9%
B. 23.8% D. 19.6%
5. Determine the degree of saturation if the moisture content reduces to 5%
in the dry season?
A. 18.2% C. 22.9%
B. 19.6% D. 23.8%
6. Determine the porosity of the soil
A. 36.9% C. 25.4%
B. 58.1% D. 44.7%

7. A 3.7-m high by 1.5-m wide rectangular gate AB is vertical and is hinged

at a point 150 mm below its center of gravity. The total depth of water
is 6.1 m. What horizontal force F (kN) must be applied at the bottom of
the gate for equilibrium?
A. 10.2 C. 16.1
B. 18.6 D. 12.4

8. A stone weighs 600 N, and when it was lowered into a square tank 0.610 m
on a side, the weight of the stone in water was 323 N. How much did the
water rise in the tank, in mm?
A. 76 C. 80
B. 72 D. 83

9. A barrel containing water weighs 1260 N. What will be the reading on the
scale (N) if a 5 cm by 5 cm piece of wood is held vertically in the water
to a depth of 0.60 m?
A. 1274.7 C. 1245.3
B. 1260.0 D. 1254.6

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CIVIL ENGINEERS Second Preboard Examination
Sunday, February 9, 2025 1:00 p.m. — 3:00 p.m. Page 2
HYDRAULICS AND GEOTECHNICAL ENGINEERING SET A
10. For a variable head permeability test, the following are given:
Length of specimen = 200 mm
Area of specimen = 1000 mm^2
Area of standpipe = 40 mm^2
Head difference at time t = 2 mins is 500 mm
Head difference at time t = 5 mins is 300 mm

Compute the hydraulic conductivity of the soil in cm/sec.

A. 3.41 × 10^-3 C. 2.27 × 10^-3
B. 1.36 × 10^-3 D. 9.73 × 10^-3

11. A shrinkage limit test on a clay soil gave the following data. Compute
the shrinkage limit.
Mass of shrinkage dish and saturated soil = 38.78 g
Mass of shrinkage dish and oven dried soil = 30.46 g
Mass of shrinkage dish = 10.65 g
Volume of shrinkage dish = 16.29 cm^3
Total volume of oven dry soil cake = 10.00 cm^3

Assuming that the total volume of dry soil cake is equal to its total
volume at shrinkage limit, what is the shrinkage limit?
A. 42.0% C. 6.7%
B. 10.2% D. 9.8%

12. 225 g of oven dried soil was placed in a specific gravity bottle and then
filled with water to constant volume mark made on the bottle. The mass of
the bottle with water and soil is 1650 g. The specific gravity bottle was
then filled with water alone to the constant volume mark and weighed. Its
mass was found to be 1510 g. Determine the specific gravity of the soil.
A. 2.45 C. 1.61
B. 1.81 D. 2.65

13. A concrete cube 0.60 m. on an edge, weighing 23.5 kN/m is placed at the
bottom of the tank in which seawater (sp.gr. = 1.03) stands 5 m. deep.
The bottom edges are sealed off so that no water is admitted under the
block. Evaluate the vertical pull required to lift the block in kN.
A. 18.69 C. 20.55
B. 19.37 D. 21.08

14. A right circular cone is 50 mm in radius and 170 mm high and weighs 1.5
N in air. How much force (N) is required to push this cone vertex-downward
into ethanol (sg = 0.79) so that its base is exactly at the surface?
A. 1.50 C. 1.75
B. 1.95 D. 1.68

15. A rectangular plate 1 m wide by 2.4 m long is vertically submerged in

water, the shorter edge 2 m. below and parallel to the water surface.
Evaluate how far in meters, below the centroid of the plate is the
resultant horizontal force acting on each side of it?
A. 0.15 C. 0.36
B. 0.24 D. 0.40

Situation 2. An open cylindrical tank 30 cm in diameter and 80cm tall is filled

with water and revolved about its own vertical axis at constant angular
speed.

16. What angular speed (rpm) will cause 1.4 liters of water to spill?
A. 45.5 C. 65.2
B. 87.2 D. 56.1
17. What will be the depth of water in the tank when it is brought to rest
from an angular speed of 240 rpm?
A. 0.55 C. 0.34
B. 0.44 D. 0.23
18. What angular speed will just zero the pressure at the bottom?
A. 255.2 C. 252.2
B. 222.5 D. 225.2

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CIVIL ENGINEERS Second Preboard Examination
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HYDRAULICS AND GEOTECHNICAL ENGINEERING SET A
Situation 3. A tank 10m long, 2m wide, is filled with 2m. of water is
accelerated horizontally 2.45 m/s2, parallel to the 10-m dimension. Assume
the tank is high enough to prevent spilling.
19. What is the minimum pressure (kPa) at the bottom of the tank?
A. 903 C. 3.7
B. 390 D. 7.4
20. What is the maximum pressure (kPa) at the bottom of the tank?
A. 37.1 C. 3.7
B. 31.9 D. 7.4
21. What is the hydrostatic force acting at the rear wall, in kN?
A. 5.5 C. 103.6
B. 23.9 D. 107.5

Situation 4. A layer of sand 5 meters deep overlies a 4 m thick bed of clay.

Assume sand has saturated unit weight & dry unit weight of 20.9 kN/m^3 &
17.4 kN/m^3 respectively, while the clay has saturated unit weight of
17.8 kN/m^3. Determine the effective stress 9 m below the ground surface
if:
22. The water table is at the ground level.
A. 118.96 kPa C. 87.41 kPa
B. 88.29 kPa D. 107. 03 kPa
23. The water table is at 2 meters below ground level and the sand above
remains saturated with capillary moisture.
A. 118.96 kPa C. 87.41 kPa
B. 88.29 kPa D. 107. 03 kPa
24. If the water table is at the top of the clay.
A. 118.96 kPa C. 87.41 kPa
B. 88.29 kPa D. 107. 03 kPa

Situation 5. Sheet piles were drived in a river bed as shown in the figure.
The trench level within the sheet piles is kept at trench level by pumping.
(k = 4 x 10-7 m/s, γsat = 20 kN/m^3).
25. Number of flow channels on each sheet pile.
A. 3 C. 4
B. 6 D. 8
26. Rate of seepage in cu.m/s.
A. 1.08 x 10^-6 C. 3.00 x 10^-7
B. 6.00 x 10^-7 D. 5.40 x 10^-7
27. Effective stress at D, if D is found 2 m below the ground.
A. 14.7 kPa C. 13.1 kPa
B. 10.5 kPa D. 11.6 kPa

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CIVIL ENGINEERS Second Preboard Examination
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HYDRAULICS AND GEOTECHNICAL ENGINEERING SET A
28. Following are the results for the backfill material used in a vibroflotation
project:
D10 = 0.11 mm
D20 = 0.19 mm
D50 = 1.3 mm
Determine the suitability number and its rating as a backfill.
A. 18.00 (Good) C. 18.00 (Fair)
B. 10.59 (Good) D. 10.59 (Fair)

29. A course grained soil has a void ratio of 0.75 and specific gravity of
2.75. The critical gradient at which quicksand condition occurs is
A. 0.25 C. 0.75
B. 0.50 D. 1.00

30. A soil with a liquidity index of -0.20 has a liquid limit of 56% and a
plasticity index of 20%. What is the natural moisture content of this soil
and the nature of this soil?
A. 12.8%, Liquid C. 12.8%, Brittle Solid
B. 32.0%, Liquid D. 32.0%, Brittle Solid

-o0o-

WARNING: Failure to submit your Test Questions (Complete) set will cause the
cancellation of your Test-Results for the subject.

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