SPSC 2011 Assistant Engineer / Assistant Executive Engineer (Civil) BPS-17, Engineers Cadre CCE (2011) — Design of Hydraulic Structures Paper

Assistant Engineer / Assistant Executive Engineer (Civil) BPS-17, Engineers Cadre CCE (2011) — Design of Hydraulic Structures. Combined Competitive Examination for Engineers Cadre · Monday 21 March 2011, 2:00 pm to 5:00 pm · Max marks 100. Attempt any 05 questions.

1. 1Draw a neat and clean sketch of a cross regulator, showing pond level on upstream side and no flow on downstream side. Show that how kinetic energy is dissipated through a hydraulic jump. (20)

2. 2What is meant by gravity dam? What are the main points to be considered while selecting a site for a gravity dam construction? Explain briefly with neat sketches the different forces acting on a gravity dam, indicate their magnitudes, directions and locations. (20)

3. 3(a) What are the main causes which create the silt trouble in storage reservoirs? (06) (b) Draw a neat sketch indicating the salient dimensions of the weir and bund section, and work out the length of the weir required with the following given data: (14) Combined catchment area A = 26 sq. km Intercepted catchment area a = 20 sq. km Maximum water level = +7.50 m Full reservoir level = +6.70 Ground level = +5.80 Reservoir bund level = +1.80 Slope on either side of bund = 2 : 1 Ryve's coefficient for combined catchment C₁ = 9.0 Ryve's coefficient intercepted C₂ = 1.8

4. 4(a) What precautions are usually taken in the design of Earth dam against wave wash and rainfall impacts? (10) (b) Draw a typical cross-section of an Earth dam showing stone revetment, filter material, key trench, launching apron and a filter toe. (10)

5. 5(a) Explain Merits and Demerits of different types of Canal linings. (06) (b) A lined canal has a full supply capacity of 30 cumecs. It will be lined with two layers of brick lining in cement mortar. The slope of the country is very steep and the canal will be aligned with hydraulic slope of 1:5000. The canal will have a trapezoidal section with side slopes at 1 : 1. Design the canal section when B = D. (14)

6. 6A distributary canal is to be crossed by a branch canal; prepare hydraulic design of an aqueduct with the following data: (20) Parameters — Branch Canal / Distributary Full supply discharge: 20 cumecs / 10 cumecs Bed width: 18.3 m / 13 m Full supply level: 106.90 / 109.05 Bed level: 104.90 / 107.71 Slope: 1:6666 / 1:6666 Mean velocity: 0.64 m/s / 0.61 m/s Angle of crossing: 90° / 90°

7. 7A canal is crossing a stream under siphoned condition. Design a siphon with following data: (20) Stream: Discharge Q = 12.33 cumecs; Highest flood level = 475.58 (at the point of crossing); Bed width B = 30 m. Canal: Q = 2.5 cumecs; V = 0.58 m/s; n = 0.0225 (unlined); Bed level = 474.70; B.W. = 1.95 m; Full supply depth = 1.30 m; Free board = 0.46 m; Hydraulic slope = 1:4,000.

8. 8(a) Describe open well irrigation system. What are the methods to be applied for increasing yields of open wells? (10) (b) Design the size (diameter) of an open well for a discharge of 3.5 l/s with an infiltration head of 3 m and s = 7.5 × 10⁻¹². (10)