A group of friction piles is shown in figure. The total load on the pile less the soil displaced by the footing is 1800kN. The clay is 16m thick. Ground water table is located 2m below the clay surface.
1. Compute for the effective pressure the mid height of the consolidating clay layer, in kPa.
A. 186.4
B. 174.8
C. 147.6
D. 163.5
2. Compute for the compression index of the clay.
A. 0.297
B. 0.245
C. 0.325
D. 0.288
3. What is the approximate settlement of the foundation?
A. 150 mm
B. 168 mm
C. 214 mm
D. 198 mm
Solution:
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A test is set-up as shown. A cylindrical mold 4” in diameter is filled with silt to height H1 = 0.2 ft, whose coefficient of permeability k1 = 6.1 x 10-4 ft/min.
A second coaxial mold is placed on top of the first mold whose inside diameter is d=1.5” and whose height is H2 = 0.30 ft. Its thickness is negligible. The inside of this second mold is filled with the same silt, but the annular ring outside the small tube and outer tube is filled with sand whose coefficient of permeability is k2 = 2.5 x 10-3 ft/min.
The test set-up is a permeameter of constant head. Water is placed in the mold and maintained at a level h=1.4ft. above the level of the outlet. It may be considered that the system consists of a fictitious soil of thickness H=H1 + H2 and coefficient of permeability kf.
The following general equations may be useful:
kv eq = H/[(H1/kv1) + (H2/kv2) + … + (Hn/kvn)]
kv eq = (1/H)[kh1H1 + kh2H2 + … + khnHn]
1. What is the total flow of water in ft3/min?
A. 2.148 x 10-4
B. 3.521 x 10-4
C. 2.554 x 10-4
D. 2.874 x 10-4
2. What is the equivalent coefficient of permeability, kf, in ft/min?
A. 1.045 x 10-3
B. 1.563 x 10-3
C. 1.874 x 10-3
D. 1.245 x 10-3
3. What is the total amount of water that percolated after 30minutes?D. 325.32 cm3
A. 217.12 cm3
B. 187.54 cm3
C. 256.32 cm3
D. 325.32 cm3
Solution:
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A cut slope was excavated in a saturated clay. The slope made an angle of 60° with the horizontal. When slope failure occurs, distance BC is 8m. Given: Stability number, m=0.185: γ=17 kN/m3; cu = 20kPa.
1. What is the stability factor?
A. 6.32
B. 5.41
C. 4.57
D. 9.36
2. Determine the critical depth of cut in meters.
A. 7.52
B. 6.36
C. 6.87
D. 5.21
3. What is the angle of failure plane in degrees?
A. 19.5
B. 25.4
C. 22.5
D. 28.6
Solution:
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A 4-meter thick sand layer is overlying a very thick dense clay layer. The water table is 2.5m below the ground (sand) surface. The sand have void ratio of 52% and the degree of saturation above water table is 37%. The clay has moisture content of 42%. Assume specific gravity of solids for both sand and clay equal to 2.65.
1. Compute for the value of the unit weight of sand above water table.
A. 18.8 kN/m3
B. 18.3 kN/m3
C. 19.3 kN/m3
D. 17.5 kN/m3
2. Compute for the value of the total stress at a depth of 10m from the ground surface, in kPa.
A. 174.5
B. 181.4
C. 196.3
D. 186.7
3. Compute for the value of the effective stress at a depth of 10m from the ground surface, in kPa.
A. 98.6
B. 132.4
C. 124.5
D. 107.8
Solution:
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Two pressurized tanks A & B are connected at the bottom by 140mm-diameter short pipe as shown in figure. The coefficients of velocity and contraction of the short pipe are 0.92 and 0.86, respectively.
1. What is the flow through the pipe in m3/s?
A. 0.214
B. 0.115
C. 0.187
D. 0.231
2. What is the head lost in meters?
A. 0.85
B. 0.53
C. 1.71
D. 1.32
3. What is the power lost in horsepower?
A. 2.59
B. 1.93
C. 2.98
D. 1.45
Solution:
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An open-top cylindrical tank 1 meter in diameter is 2.80m tall. The tank floats in water with a draft of 2.30 meters. Unit weight of lead is 110 kN/m3.
1. What is the weight of tank in KiloNewtons?
A. 19.54
B. 21.57
C. 15.24
D. 17.72
2. How much lead (in KiloNewtons) must be fastened to the outside bottom of the tank in order make it completely submerged in water?
A. 100m
B. 120m
C. 150m
D. 80m
3. How much lead (in KiloNewtons) must be place inside the tank in order make it completely submerged in water?
A. 4.87
B. 4.21
C. 3.85
D. 3.24
Solution:
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Dry soil is mixed with 17% by weight with water and then compacted. The moist soil has a volume of 1 x 10-3 m3 and a mass of 1.6kg. The soil solids have specific gravity of 2.70.
Determine the following:
1. What is the dry unit weight of the soil in kN/m3?
A. 14.25
B. 13.42
C. 12.54
D. 15.63
2. What is the void ratio of the soil?
A. 97.4%
B. 86.35%
C. 95.85%
D. 92.54%
3. What is the degree of saturation of the soil?
A. 32.21%
B. 25.87%
C. 47.12%
D. 52.32%
Solution:
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A 600-mm non-rigid pipe takes water from a large reservoir. The velocity of flow in the pipe is 2.5 m/s. The flow is suddenly stopped by a quick-closing valve situated 400 m from the reservoir. The pipe is 20mm thick and modulus of elasticity of pipe material is 1.4 x 1011Pa. Bulk modulus of elasticity of water is 2.2 x 109Pa.
1. Compute for the value of the celerity of pressure wave in m/s.
A. 1532
B. 1223
C. 1142
D. 1358
2. Compute for the time for the pressure wave to travel round trip along the pipe.
A. 0.74sec
B. 0.96sec
C. 0.85sec
D. 0.65sec
3. What is the maximum water hammer pressure developed on the pipe due to instantaneous closure of the valve?
A. 3057 kPa
B. 3185 kPa
C. 3263 kPa
D. 3321 kPa
Solution:
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A pump draws 20 liters per second of water from reservoir C and lifts it to reservoir D as shown. The head lost from C to 1 is three times the velocity head in the 150-mm suction line and the head lost from 2 to D is fifteen times the velocity head in the 100-mm discharge line.
1. What is the power delivered by the pump to the system?
A. 62.6 horsepower
B. 64.5 horsepower
C. 75.6 horsepower
D. 87.4 horsepower
2. What is the pressure head at point 1 in meters of water?
A. 32.56m
B. 48.57m
C. 19.74m
D. 15.23m
3. What is the pressure head at point 2 in meters of water?
A. 187.56m
B. 264.63m
C. 321.27m
D. 242.33m
Solution:
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A closed conical tank, upright is position, has a bottom radius of 30cm and a height of 65cm.
1. What is the total volume of the tank in cubic meter?
A. 0.0541
B. 0.0963
C. 0.0852
D. 0.0613
2. If the tank contains 0.022m3 of water, how much water is required to fill the tank?
A. 0.0236m3
B. 0.0147m3
C. 0.0586m3
D. 0.0393m3
3. If the tank contains 0.022m3 of water, what is the depth of water in the tank?
A. 0.09m
B. 0.05m
C. 0.08m
D. 0.12m
Solution:
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A 10-m wide rectangular channel have a flow of 17.6 m3/s when the depth of flow is 1.20m. Use n= 0.014.
1. Compute for the value of the minimum specific energy in meter.
A. 1.32m
B. 1.02m
C. 0.85m
D. 1.63m
2. What is the normal slope?
A. 0.00055
B. 0.00022
C. 0.00044
D. 0.00033
3. What is the average boundary shearing stress in Pa?
A. 4.18Pa
B. 6.85Pa
C. 25.87Pa
D. 102.45Pa
Solution:
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