DESIGN OF HYDRAULIC STRUCTURES

a) Explain the Khosla’s theory of independent variables. (6)
b) Explain the components of unlined canal sections with sketches. (5)

c) Explain the causes of failure of weirs on permeable soils. (4)

a) A hydraulic structure built on fine sand has the following details: (6) Total length of the floor = 29 m, a weir at 6 m from u/s end, effective head of water 4 m, sheet pile at u/s end 5 m deep, sheet pile at d/s end 6 m deep, intermediate piles of 3 m depth at 12 m from u/s end. Determine: a) Average hydraulic gradient, b) Uplift pressures at points A = 6 m, and B = 20 m from upstream end and corresponding thicknesses of floor using Bligh’s theory. Specific gravity of floor material is 2.24.
1. Compare Kennedy’s theory and Lacey’s theory for design of canals through (4) alluvial soils.
2. Explain the different types of canal falls (5)
a) Using Lacey’s theory, design a regime channel for a discharge of 43 cumecs, (6) side slopes ½: 1 and silt factor 1.1.
1. Explain the different types of aqueducts. (4)
2. What are the general considerations for canal alignment? (5)

a) Design a suitable cross drainage work, for the following data at the crossing of a (25) canal and a drainage.

Canal:

Full supply discharge = 42 cumecs

Full supply level = 192.7 m

Canal bed level = 191.0 m

Canal bed width =26 m

Trapezoidal canal section with 1.5 H: 1 V slopes Canal water depth = 1.7 m.

Drainage:

High flood discharge = 340 cumecs.

High flood level = 189.0 m High flood depth = 2.7 m.

General ground level = 191.5 m.

b) Prepare the following drawings (not to scale) (25)
Half plan at top and half at foundation level.
Section through the centre line of the drain.

a) Design a Sarda Type fall with drop of 1.4 m for a canal carrying a discharge of (25) 35 cumecs with the following data:

Bed level upstream = 104 m

Bed level downstream = 102.6 m

Side slopes of channel = 1:1

Full supply level upstream = 105.6 m

Bed width u/s and d/s = 27 m

Safe exit gradient = 1/5

b) Prepare the following drawings (not to scale) (25)
1. Half plan at top and half at the foundation level.
2. Section through the centre line of the canal.

a) Explain chute spillway and side channel spillway. (4) b) List the forces acting in a gravity dam. (2)
1. What is a stilling basin? Explain Type I and Type II stilling basins. (4)
a) What are the functions of gallery in a gravity dam? (2) b) With the help of a neat sketch, derive the expression for thickness of arch ring at (4) a depth ‘h’ m below the water surface in the reservoir.
1. What is meant by elementary profile of a gravity dam? (4)
Check the stability of the gravity dam with the following data: (10)

Reduced level of the dam at the base = 90 m

Height of dam = 250 m

Maximum water surface elevation = 336 m

Top width = 8 m

Upstream face is vertical and downstream face is vertical up to elevation 330 m and has a slope of 0.8 horizontal to 1 vertical below this elevation. Assume no tail water and no drainage galleries. Density of concrete is 24 kN/m³ and coefficient of friction is 0.75.

(06 Marks)

List out the various forces acting on a gravity dam.

b. A solid gravity dam is to be constructed with concrete (1: 2: 4) having ultimate compressive strength of 15800 kN/m. Find out the height upto which the dam may be

considered as a low dam. Assume factor of safety- 4 and specific gravity of concrete- 2.4. (02 Marks) e. From the following data, design and sketch the practical profile of a gravity dam of stone

masonry:

HFL 155.50 m: Permissible stress in

Ground level 130.50 m: Sp. Gravity of masonry-2.25:

Wave height 1.0m: stone masonry- 1250 kN/m²

(08 Marks)

OR a. Explain the concept of elementary profile of a gravity dam and how it is helpful in

2 classifying a dam as low and high. (06 Marks) b. A triangular section of a gravity dam having base width 30 m and height 40 m is stored with water upto top. Analyse the dam section and determine (i) Factor of safety against sliding (ii) Factor of safety against overturning (ii) The normal stresses in the base of the dam. Assume, co-efficient of friction between the base and foundation as 0.7, uplift pressure intensity co-efficient as 0.45 and unit weight of dam material-24 kN/m. (10 Marks)

Module-2 What are earthen dams and mention the advantages of earthen dam?

(04 Marks) (12 Marks)

b. Explain the different types of failures of earthen dams with sketches.

A homogeneous earthen dam is 43 m high. The free board provided is 3 m. The flownet comprised 5 flow channels and 15 potential drops. If the permeability of the material in the dam is 3x10 m/sec. Calculate the seepage flow per metre length of the earth dam. If the dam is 500 m long, calculate the total discharge through the body of the dam. (04 Marks) A earth dam of a homogeneous material has the following data: Co-efficient of permeability of damn material- 5x10 cm/sec b.

Top bund level-200.00 m

Bed level 194.00 m MWL 198.5 m

Top width of dam-2.0 m Upstream slope = 1.5:1

Downstream slope 2:1

Draw the phreatic line for this dam section and calculate the seepage discharge passing through the dam if a horizontal filter of length equal to 5.3 m is provided inward from the downstream to the dam. (12 Marks)

5 a b. What are spillways? What are the types of spillways? Design and draw the cross section of an Ogee spillway, when the maximum head over it is 2.76 m, the height of the spillway is restricted to 30 m.

(12 Marks)

a. Draw the typical layout of the diversion head work and name its components. (06 Marks) b. Fig. Q6 (b) shows the cross section of a hydraulic structure constructed on sand. Calculate the average hydraulic gradient. Also calculate the uplift pressure at points 6 m, 12 m and 18 m from the U/S end of the floor and find the thickness of the floor at those points taking p-2.24

(10 Marks)

22m

Fig. Q6 (b)

Module-4

7 a What is meant by cross drainage works? Describe with the help of neat sketches

types of C.D works.

various

b What are the factors to be considered for the selection of site for CD works? (04 Marks)

What do you understand by level crossing?

OR Design a suitable cross drainage work at the crossing of a canal and a drainage for the

following particulars:

CANAL: Full supply discharge = 32 m/sec

(02 Marks)

Full supply level=213.50 m, Canal bed level-212.00 m.

Canal bed width-20.0 m, Trapezoidal section with 1.5 H: 1 V

Assume Rugosity co-efficient (Manning's) N 0.017. Drainage: High flood discharge-30 cumecs

High flood level-210.00 m, High flood depth 2.5 m

Assume, velocity of water as 2.15 m/sec in the canal trough

What is meant by canal regulation? What are the different canal regulation works (05 Marks) b. Differentiate between cross regulator and distributary head regulator. State the functions of a

cross regulator.

c. What is a canal fall? Write the points to be considered for selection of site for a fall

(06 Marks)

(05 Marks)

OR 10 a What are canal outlets? Mention the requirements of a good outlet (module). (06 Marks) b. How are modules classified? Briefly explain each type of modules.