Hydrogeo preboard 3 a PDF

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CE GREAT MINDS PREBOARD 3HYRAULICS AND GEOTECHNICAL ENGINEERINGINSTRUCTION: Select the best 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. Use pen...

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CE GREAT MINDS PREBOARD 3 HYRAULICS AND GEOTECHNICAL ENGINEERING INSTRUCTION: Select the best 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. Use pencil no. 2 only. 1.

A canal has hydraulic radius of 0.41 m, slope = 0.008, roughness coefficient = 0.025. Find the value of C using Kutter Formula. a. 33.7 b. 34.2 c. 35.8 d. 32.9

2.

Carbon tetrachloride with a mass of 500 kg is placed in a container with 0.315 m^3 in volume. Find the specific gravity. a. 1.587 b. 1.618 c. 1.954 d. 0.876

3.

A saturated clay layer has a thickness of 10 m with a water content of 51% and a sp gr. of 2.72. Find the effective stress at the bottom. a. 61.9 kPa b. 70.6 c. 84.7 d. 91.2

SITUATION 1: The moist unit weight of a soil is 16.5 kN/m^3. Given that the ω = 0.15, Gs = 2.70, 4. 5. 6.

Determine the porosity of the soil. a. 0.46 b. 0.64

c. 0.31

d. 0.55

Determine the degree of saturation. a. 0.84 b. 0.36

c. 0.48

d. 0.75

Determine the mass of water in kg/m^3 that must be added to reach full saturation. a. 2986 b. 2079 c. 2340 d. 2716

SITUATION 2: A jet discharges 5.19 L/s from a 35 mm ϕ orifice in a vertical plane under a head of 4 m. The jet centreline passes through the point 4.28 m horizontally from the vena contracta and 1.2 m below the center of the orifice. 7. 8. 9.

Find the coefficient of discharge. a. 0.719 b. 0.609

c. 0.551

d. 0.389

Find the coefficient of velocity. a. 0.977 b. 0.516

c. 0.781

d. 0.638

Find the coefficient of contraction. a. 0.623 b. 0.571

c. 0.489

d. 0.712

SITUATION 3: A given layer of soil has a dry unit weight of 14.72 kN/m3 and a saturated unit weight of 20.12 kN/m3. The ground water table is located 2m. below the ground surface. 10. Determine the total stress point at A 4.5 m below the ground surface. a. 88.15 kPa b. 107.59 c. 91.23 d. 79.74 11. Find the pore pressure at A at the same surface a. 24.53 kPa b. 37.20 c. 51.19

d. 64.77

12. Find the effective stress at A at the same surface. a. 59.13 kPa b. 68.12 c. 44.87

d. 55.21

SITUATION 4: A confined aquifer shown in the figure has a source of recharge. The hydraulic conductivity of the aquifer is 35 m/day with a porosity of 25%. The head surface in the two observation wells 1000 m apart are shown. The aquifer has an average thickness of 4 m and and average width of 4 km.

13. Determine the nearest value to the rate of flow of water through the aquifer. a. 5500 m^3/day b. 5600 c. 5200 d. 5800 14. Determine the seepage velocity in m/day. a. 1.4 m/day b. 1.5

c. 1.3

d. 1.2

15. Find the time of travel from the head of aquifer to a point 4 km downstream in days. a. 2667 b. 2857 c. 3077 d. 3333 SITUATION 5: The elasticity and dimensions of the pipe are such that celerity of the pressure wave is 970 m/s. Suppose the pipe has the length of 1600 m and 1.2 m ϕ flowing at 0.85 m^3/s. 16. Find the water hammer pressure for instantaneous valve closure. a. 447.9 kPa b. 319 c. 727.5

d. 918.6

17. Find the time allowed for closing a valve to avoid water hammer. a. 5.16 s b. 1.88 c. 3.30

d. 4.68

18. Find the water hammer pressure of the valve if it is closed in 4 secs. a. 600.19 kPa b. 557.13 c. 648.21 d. 733.96 SITUATION 6: A consolidated drained tri axial test was conducted on a normally consolidated clay. The results as follows: Chamber confining pressure = 138 kPa Deviator stress = 258 kPa 19. Find the friction angle of soil. a. 28.89° b. 33.18°

c. 34.73°

d. 39.12°

20. Find the normal stress at failure. a. 179.20 kPa b. 204.68

c. 222.19

d. 181.45

21. Find the shear stress at failure. a. 107.47 kPa b. 256.79

c. 112.95

d. 184.45

22. The potential energy at the optimum cost , the design criteria focus on the choice of location, design discharge and head by suitable numerical techniques. This system is known as: a. Water supply optimization c. Water power utilization b. Wastewater treatment d. Sanitary management SITUATION 7: A liquid having a Reynolds number of 1900 flows through a 200 mm ϕ pipe, 150 m long. The head loss of the pipe due to friction is 22 m. 23. Compute the friction factor. a. 0.034 b. 0.047

c. 0.055

24. Determine the kinematic viscosity. a. 1.774 x 10^-5 m^2/s b. 1.623 x 10^-5

c. 1.815 x 10^-5 d. 1.368 x 10^-5

25. Compute the rate of flow in L/s. a. 1470 b. 1555

c. 1389

d. 0.060

d. 1929

26. An object weighs 4 N in water and 5 N in an alcohol (S = 0.80). Use γw = 9.79 kN/m^3. Find the density of the object. a. 1900 kg/m^3 b. 1868 c. 1519 d. 1796 27. The specific gravity and density of water is highest when the temperature is : a. 0℃ b. 4℃ c. Below zero d. 100℃ SITUATION 8: A 600 mm ϕ pipe , 10 mm thick carries water under a head of 325 m. 28. Determine the actual stress in kN per meter length of pipe. a. 95.65 MPa b. 100.77 c. 109.21

d. 74.58

29. If the head is increased to 500 meters, what is the actual stress on the wall in MPa? a. 124.58 MPa b. 100.21 c. 147.15 d. 158.61 30. If the head is increased to 500 meters, what thickness is required assuming , an allowable tensile stress of 113 MPa and efficiency of the connection is 80%? a. 15.2 mm b. 16.3 c. 19.3 d. 21.6 31. It refers to the ice coating generally clear and smooth , formed on exposed surfaces by the freezing super cooled water deposited by rain or drizzle. a. Rime b. Snow c. Glaze d. Drizzle SITUATION 9: From a given data , shows a sieve analysis of soil samples A, B and C. Sieve No. 4 8 10 20 40 60 100 200

Diameter(mm) 4.760 2.380 2.000 0.840 0.420 0.250 0.149 0.074

Liquid Limit Plastic Limit

A 90 64 54 34 22 17 9 4

B 100 90 77 59 51 42 35 33

c 100 100 98 92 84 79 70 63

-----

46 29

47 24

Refer to the last page of the exam. 32. Classify soil A. a. SW

b. SC

c. SP

d. CL

33. Classify soil B. a. SC

b. GP

c. CL

d. GW

c. 93

d. 23

34. Find the Plasticity index in soil C. a. 1 b. 0

SITUATION 10: A vertical retaining wall 6 m high retains a horizontal backfill having the following properties: Void ratio = 0.60 Sp gr = 2.60 Water content = 24% Angle of internal friction = 25° 35. Compute the magnitude of the active force acting on the wall if the water surface is on the ground surface which is on level with the top of the wall. a. 222.16 kN/m b. 262.48 c. 219.06 d. 248.27 36. Compute the magnitude of the active force acting on the wall if the water table is lowered at a depth of 3 m. from the ground surface. a. 119.36 kN/m b. 124.58 c. 131.90 d. 149.42 37. Compute the magnitude of the active force acting on the wall if the water table is at the bottom of the wall. a. 108.30 kN/m b. 116.30 c. 144.48 d. 100.38 SITUATION 11: The flow rate of the pipe system is shown is 50 L/s under a total head loss from A to D equal to 9 m. Using C = 120 for all pipes.

38. Compute the head loos of pipeline B. a. 1.90 m b. 0.88

c. 1.32

d. 1.61

39. Compute the discharge of pipeline B. a. 0.078 m^3/s b. 0.019

c. 0.117

d. 0.036

40. Compute the diameter of pipeline C. a. 150 mm b. 180

c. 130

d. 220

SITUATION 12: A group of friction piles in deep clay is shown in the figure. The total load on the piles reduced by weight of soil displayed by the foundation is 1800 kN. Thickness of silt is 2 m. and that of clay is 16 m.

41. Compute the effective overburden pressure. a. 131.78 kPa b. 142.59

c. 161.58

42. Compute the compression index of the clay layer. a. 0.226 b. 0.268 c. 0.315

d. 127.20 d. 0.417

43. Compute the approximate total settlement of the pile foundation. a. 145 mm b. 180 c. 215

d. 160

44. He observed that, if the soil behind the sheet-pile wall has grain sizes that are predominantly smaller than those of coarse sand, the active earth pressure after construction sometimes increases to an at-rest earth-pressure condition. a. Das b. Boussinesq c. Casagrande ` d. Terzaghi SITUATION 13: A straight tube 1.2 m long closed at the bottom and filled with water is inclined 30° with vertical and rotated about a vertical axis through its midpoint at 8.02 rad/s as shown in the figure.

45. Compute the value of y. a. 0.318 b. 0.412

c. 0.295

d. 0.107

46. Compute the pressure at the bottom of the tube. a. 11.18 kPa b. 19.22 c. 10.20

d. 8.77

47. Compute the pressure at the midpoint of the curve. a. 2.20 kPa b. 1.77 c. 0.89

d. 3.37

48. An aeroplane weighing 65 kN, has a wing area of 27.5 m^2 and a drag coefficient of Cd = 0.02 + 0.061x(CL)^2 . Assume for air at ambient conditions, Density is 0.96 kg/m^3. Determine the lift coefficient if the craft is cruising at 700 km/h. a. 0.077 b. 0.021 c. 0.038 d. 0.088 SITUATION 14: A pump draws water from reservoir A and lifts it to reservoir B as shown. The loss of head from A to 1 is three times the velocity head in the 150 mm pipe and the loss from 2 to B is 15 times the velocity head in the 100 mm pipe when the discharge is 20 L/s.

49. Determine the horsepower output of the pump in kW. a. 40.20 kW b. 49.77 c. 48.10

d. 44.36

50. Compute the pressure head at point 1. a. 11.38 m b. 9.16

d. 19.74

c. 15.26...