Hydrau Geo 1

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CIVIL ENGINEERING Mock Examination MAY 2016 HYDRAULICS & GEOTECHNICAL ENGINEERING 1. A cohesive soil deposit is considered soft if the unconfined compression strength, in kPa, is between A. 0 to 24 C. 96 to 192 B. 48 to 96 D. 24 to 48 2. A fireman has to put out a fire but is blocked by a fire wall. To reach over the wall, he directed the water jet from the nozzle at an angle of 30 deg to the horizontal. Evaluate the velocity of the water, in meters/sec, leaving the nozzle of his hose to reach over the wall if he stands 30 meters away from the wall and the wall is standing 2 m higher than the nozzle of the hose. Neglect friction in the jet. A. 16.8 C. 18.2 B. 20.6 D. 19.6 3. A line joining the points of highest elevation of water in a series of vertical open pipes rising from a pipeline in which water flows under pressure is referred to as A. hydraulic loss C. hydraulic jump B. hydraulic gradient D. hydraulic head 4. In a triaxial shear test of a cohesionless soil, the soil cylinder was subjected to a liquid pressure of 16 kPa inside the chamber. It was observed that failure of the sample in shear occurred when the axial compressive stress reached 40 kPa. The angle of internal friction in degrees is nearest to A. 27.4 C. 26.8 B. 29.1 D. 25.4 5. A barge, weighing 350 kN when empty, is 6 m wide, 15 m long, and 3 m high. Floating upright, evaluate the draft of the barge, in meters, when transporting 3000 bags of cement along a river, each bag having a mass of 40 kg. Assume the specific gravity of the water in the river to be 1.02. A. 1.38 C. 2.01 B. 2.57 D. 1.67 6. A spherical balloon 6 m in diameter is filled with gas weighing 5 N/m-3. In standard air weighing 12 N/m-3, evaluate the maximum load, in N, excluding its own weight, that the balloon can lift. A. 812 C. 672 B. 792 D. 916 7. Determine the pressure in a vessel of mercury at a point 200 mm below the liquid surface, expressing the answer in kPa absolute. A. 132 C. 134 B. 130 D. 128 8. Water flows through a rectangular irrigation canal, 500 mm deep by 1 m wide, with a mean velocity of 2 meters per second. Determine the rate of flow in m^3 per minute. A. 50 C. 80 B. 70 D. 60 Page 1 of 8 CIVIL ENGINEERING Mock Examination MAY 2016 HYDRAULICS & GEOTECHNICAL ENGINEERING 9. A layer of soft clay having an initial void ratio of 2.00 is 10 m thick. Under a compressive load applied above it, the void ratio decreased by one-half. Evaluate the reduction in the thickness of the clay layer, in meter(s). A. 3.50 C. 3.33 B. 3.74 D. 3.15 10. A ship having a displacement of 20,000 metric tons enters a harbor of fresh water. The ship captain recorded a draft of 8.4 m while the ship was still in seawater (specific gravity = 1.03). Obtain the draft, in meters, of the ship in fresh water if the horizontal section of the ship below the waterline is 3000 m2 in both instances. A. 8.75 C. 9.54 B. 7.78 D. 8.59 11. A pressure surge or wave caused when a fluid in motion is forced to stop or change direction suddenly (momentum change) is referred to in hydraulics as A. potential head C. water hammer B. hydraulic jump D. hydrodynamics 12. Evaluate the resisting capacity against axial load due to skin friction Size of pile: 0.30 m square Depth of penetration into the Unconfined compression strnegth A. 1010 C. B. 1320 D. 660 13. The permeameter in a falling head permeability test setup involves a cylindrical soil sample 50 mm in diameter and a height 200 mm. The hydraulic head in the 10-mm diameter standpipe through which test water passed dropped from 900 to 600 mm in one-minute of observation. In that duration the water collected in the graduate was recorded at 1.5 liters. Evaluate the coefficient of permeability of the soil sample, in cm/sec. A. 0.00924 C. 0.00715 B. 0.00541 D. 0.00689 14. A soil sample has a water content of 20 percent and moist unit weight of 18 kN/m^3. The specific gravity of the solids is 2.65. Obtain the void ratio of the soil. A. 0.407 C. 0.733 B. 0.635 D. 0.368 15. For the tank shown in FIGURE HHP-1, obtain the depth d, in meters, of the oil if its specific gravity is 0.84. A. 1.44 C. 1.37 B. 1.19 D. 1.28 16. An unconfined compression test was conducted on a sample of clay having a diameter of 50 mm. The failure load was recorded at 240 N. The cohesion strength of the clay, in kPa, is nearest to a value of A. 64.0 C. 61.1 B. 45.0 D. 101.0 Page 2 of 8 CIVIL ENGINEERING Mock Examination MAY 2016 HYDRAULICS & GEOTECHNICAL ENGINEERING 17. When the path lines of the individual particles of a flowing liquid are irregular curves and continually cross each other and form a complicated network, the flow is called A. uniform C. continuous B. laminar D. turbulent 18. A trapezoidal canal has a bottom width of 4 m and side slopes of 2 horizontal to 1 vertical. When the depth of the flow is 1.2 m, the flow is 30 m^3/sec. The roughness coefficient n = 0.015. Evaluate the slope of the channel using Mannings formula. A. 0.00195 C. 0.00412 B. 0.00316 D. 0.00447 19. A layer of soft clay having an initial void ratio of 1.50 is 10 m thick. Under a compressive load applied above it, the void ratio decreased by one-half. Evaluate the reduction in the thickness of the clay layer. A. 4.25 C. 3.00 B. 3.75 D. 5.50 20. If the velocity head at one point of a pipeline is 5 m, what would be the velocity head, in meters, at the point of the pipeline if the velocity is increased three times? A. 20 C. 15 B. 45 D. 30 SITUATIONAL Situation 1 – The coefficient of permeability below a dam is 4 m/day. The water on the upstream side is 20 meter higher than on the downstream side. To estimate the seepage below the dam, a flow net was graphically drawn such that the number of potential drops, Nd=10 and the number of flow channels Nf=4. The base of the dam is founded 1 m below the ground. Between the heel and the toe of the dam, a distance of 30 meters, there are 8 potential drops. 21. Evaluate the seepage flow per meter width of dam, in liters/min. A. 18.6 C. 32.5 B. 20.6 D. 22.2 22. Determine the uplift pressure at the heel of the dam, in kPa. A. 198 C. 177 B. 181 D. 114 23. Determine the uplift pressure at the toe of the dam, in kPa. A. 11.4 C. 19.6 B. 14.7 D. 17.6 Situation 2 – According to the elastic theory, the vertical stress induced by flexible line load of infinite length that has an intensity of q units/length on the surface of a semi-infinite soil mass can be estimated by the expression p = 0.637 q/N when N = z[1+(r/z)2]2 Page 3 of 8 CIVIL ENGINEERING Mock Examination MAY 2016 HYDRAULICS & GEOTECHNICAL ENGINEERING r = horizontal distance from the line of the load z = depth of interest at which stress is induced A concrete hollow block wall weighing 6 kN per lineal meter is carried by a wall footing 0.60 m wide. 24. Evaluate the bearing pressure, in kPa, exerted by the footing onto the supporting soil. A. 14 C. 10 B. 12 D. 16 25. Evaluate the stress in the soil caused by the load depth equal to twice its width. A. 7.25 C. 4.43 B. 6.47 D. 5.31 26. Evaluate the stress at a depth of 2 m and a horizontal distance of 3 m from the line of the load. A. 0.432 C. 0.668 B. 0.531 D. 0.302 Situation 3 – In FIGURE HTRS-2, reservoir A is the source of water supply and is at Elev. 150 m, B is the junction at Elev. 91.46 m, C is a town at Elev. 30.49 m with 25,000 inhabitants, D is another town at Elev. 15.24 m with a population of 30,000. Length AB is 15,240 m, BC is 9150 m, BD is 6100 m. Determine the size of the pipes if the consumption is 150 liters per capita per day. For the pipes, frictional factor f = 0.02. Determine the required diameter, in meters, of 27. pipe AB A. 0.450 B. 0.330 C. 0.390 D. 0.420 28. pipe BC A. 0.366 B. 0.500 C. 0.216 D. 0.196 29. pipe AB C. 0.450 D. 0.205 C. 0.300 D. 0.150 Situation 4 – A square footing 4 m on a side is founded 1.2 m below the ground surface for which the bulk unit weight of the soil is 20 kN/m^3, the cohesion strength is 10 kPa, and the angle of internal friction is 20 deg. Under the condition of general shear failure, evaluate the contribution of the following to the ultimate soil bearing capacity, in kPa. The ground water table is at a level that does not affect the unit weight of the soil. Use Terzaghi’s bearing capacity factors. TABLE SMBC can be useful. 30. cohesion strength A. 259 B. 235 C. 230 D. 287 31. soil overburden A. 247 B. 260 C. 179 D. 185 Page 4 of 8 CIVIL ENGINEERING Mock Examination MAY 2016 HYDRAULICS & GEOTECHNICAL ENGINEERING 32. footing dimension A. 98 B. 116 C. 128 D. 102 Situation 5 – A rectangular gate 1.5 m wide and 3 m high is vertically submerged in water with its top edge horizontal and 2mbelow the water surface. 33. Evaluate the total force acting on one side of gate, in kN. A. 177 C. 154 B. 143 D. 165 34. Obtain the location of the force from the center of gravity of the plate, in meter(s) A. 0.316 C. 0.214 B. 0.225 D. 0.355 35. Obtain the location of the force from the liquid surface, in meters. A. 3.71 C. 3.82 B. 3.96 D. 3.61 Situation 6 – A solid block having a specific gravity of 3.5 is placed in a container containing liquid having specific gravity of 13.6. 36. If the volume of the block is 0.020 cubic meter, obtain the weight of the block, in kN. A. 0.824 C. 0.566 B. 0.687 D. 0.751 37. Evaluate the percentage volume of the block that floats in the liquid. A. 82.5 C. 67.3 B. 74.3 D. 53.3 38. Obtain the downward force in kN required to make it completely submerged in the liquid. A. 1.05 C. 1.98 B. 3.22 D. 2.05 Situation 7 – An irrigation canal with trapezoidal cross sections has the following dimensions: Bottom width = 2.00 m, depth of water = 0.90 m, side slope = 1.5 horizontal to 1 vertical, slope of the canal bed = 0.001, coefficient of roughness = 0.025. The canal will serve clay-loam Riceland for which the duty of water per hectare is 3.0 liters/sec. Using Manning’s formula: V = (R^2/3)(S^1/2)/n, 39. determine the hydraulic radius of the canal, in meter(s) A. 0.432 C. 0.501 B. 0.242 D. 0.575 40. velocity of the water in m/sec. A. 0.308 C. 0.652 B. 0.479 D. 0.874 41. number of hectares served by the irrigation canal. A. 897 C. 978 B. 879 D. 789 Page 5 of 8 CIVIL ENGINEERING Mock Examination MAY 2016 HYDRAULICS & GEOTECHNICAL ENGINEERING Situation 8 – A soil sample has a dry unit weight of 17 kN/m^3 and a void ratio of 0.60. 42. Evaluate the specific gravity of the soil solids. A. 2.44 C. 2.77 B. 2.65 D. 2.56 43. Obtain the unit weight of the sample in kN/m^3 when fully saturated. A. 21.3 C. 20.7 B. 18.6 D. 19.6 44. What is the hydraulic gradient at hydraulic condition? A. 1.43 C. 1.35 B. 1.11 D. 1.28 Situation 9 – A rectangular irrigation canal 6 m wide contains water 1.0 m deep. It has a hydraulic slope of 0.001 and a roughness coefficient of 0.013. 45. Evaluate the mean velocity of the water in the canal, in m/sec. A. 1.52 C. 2.01 B. 1.06 D. 1.38 46. Evaluate the discharge in the canal, in m^3/sec. A. 10.8 C. 11.5 B. 13.8 D. 12.0 47. What would have been the depth of the canal, in meters, using the more economical proportions but adhering to the same discharge and slope? A. 2.38 C. 1.67 B. 2.06 D. 2.52 Situation 10 – An open cylindrical vessel 1.3 m in diameter and 2.1 m high is 2/3 full of water. If rotated about the vertical axis at a constant angular speed of 90 rpm, 48. Determine how high is the paraboloid formed of the water surface, in meter(s). A. 1.26 C. 2.46 B. 1.91 D. 1.35 49. Determine the amount of water in liters that will be spilled out. A. 140 C. 341 B. 152 D. 146 50. What should have been the least height of the vessel, in meters, so that no water is spilled out? A. 2.87 C. 3.15 B. 2.55 D. 2.36 Page 6 of 8 CIVIL ENGINEERING Mock Examination MAY 2016 Oil d Water 4 m 3 m Water FIGURE HHP-1 Elev. 150 Town C Elev. 30.49 A B Elev. 91.46 Town D Elev. 15.24 FIGURE HTRS-2 Page 7 of 8 CIVIL ENGINEERING Mock Examination MAY 2016 Table SMBC – Terzaghi’s Bearing Capacity Factors Φ deg 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 General Nc 5.70 6.00 6.30 3.62 6.97 7.34 7.73 8.15 8.60 9.09 9.61 10.2 10.8 11.4 12.1 12.9 13.7 14.6 15.1 15.6 17.7 18.9 20.3 21.8 23.4 25.1 27.1 29.2 31.6 34.2 37.2 qu = KccNc qu γ  = B = c = Df = Nc Nq Nγ q = Kc Kq Kγ + shear failure Nq Nγ 1.00 0.00 1.10 0.01 1.22 0.04 1.35 0.06 1.49 0.10 1.64 0.14 1.81 0.20 2.00 0.27 2.21 0.35 2.44 0.44 2.69 0.56 2.98 0.69 3.29 0.85 3.64 1.04 4.02 1.26 4.45 1.52 4.92 1.82 5.45 2.18 6.04 2.59 6.70 3.07 7.44 3.64 8.26 4.31 9.19 5.09 10.2 6.00 11.4 7.08 12.7 8.34 14.2 9.84 15.9 11.6 17.8 13.7 20.0 16.2 22.5 19.1 Local shear failure N’c N’q N’γ 5.70 1.00 0.00 5.90 1.07 0.01 6.10 1.14 0.02 6.30 1.22 0.04 6.51 1.30 0.06 6.74 1.39 0.07 6.97 1.49 0.10 7.22 1.59 0.13 7.47 1.70 0.16 7.74 1.82 0.20 8.02 1.94 0.24 8.32 2.08 0.30 8.63 2.22 0.35 8.96 2.38 0.42 9.31 2.55 0.48 9.67 2.73 0.57 10.06 2.92 0.67 10.47 3.13 0.76 10.90 3.36 0.88 11.36 3.61 1.03 11.85 3.88 1.12 12.37 4.17 1.35 12.92 4.48 1.55 13.51 4.82 1.74 14.14 5.20 1.97 14.80 5.60 2.25 15.53 6.05 2.59 16.30 6.54 2.88 17.10 7.07 3.29 18.03 7.66 3.76 18.99 8.31 4.39 KqγDfNq + KγγBNγ = ultimate bearing capacity unit weight of the soil width of footing cohesion of soil depth of founding of footing = bearing capacity factors overburden pressure = constants General shear failure Footing Kc Kq Long 1.00 1.00 Square 1.30 1.00 Circular 1.30 1.00 For local shear failure, the value of c is reduced by Kγ 0.50 0.40 0.30 1/3. 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