Bài giảng công trình trên hệ thống thủy lợi

Classification cont.4-Based on form of gates: Plain, radial, drum, flap, roller, fabric gates... 4-Based on form of gates cont.: Radial gate... 4-Based on form of gates cont.: Flap gate.

1 INTRODUCTION

What are valves and gates?

Which types are valves and gates classified?

1.2 Classification

1-Based on function: Service, maintenance, emergency gates

1.2 Classification (cont.)

3-Based on mode of operation:

to let water out under the gate

to let water out over the gate

Combination between the above types

1.2 Classification (cont.)

4-Based on form of gates: Plain, radial, drum, flap, roller, fabric gates

4-Based on form of gates (cont.): Radial gate

4-Based on form of gates (cont.): Drum and sector gates

4-Based on form of gates (cont.): Flap gate

4-Based on form of gates (cont.): Roller gate

1.2 Classification (cont.)

5-Based on moving mechanism: Gates are

moved-electrically

mechanically

automatically by water pressure

6-Based on material: Gates made of steel, reinforced 6-Based on material: Gates made of steel, reinforced concrete or other synthetic materials

1.2 Classification (cont.)

7-Based on position: Crest and submerged gates

frame gate; l) Braked gate; m) Air-made gate.

1.2 Classification (cont.)

8-Tidal barrage and surge protection gates

2 CALCULATION OF PLAIN GATE (VERTICAL LIFT)

Hydrostatic pressure;

Hydrodynamic pressure;

Weight of the gate;

Frictions;

2.1 Forces acting on the gate

Forces caused by floating objects

2.2 Necessary driving forces to open or close the gate

a General formulas:

Opening driving force:

2 1

Closing driving force:

G '.

K )

T T

.(

K G

K

P2 = 1 d + 2 1 + 2 −

G- Weight of the gate;

T1- Friction between gate and abutment;

T2- Friction at watertight components;

Gd –Weight of counterpoise;

K1, K2, K’: Safety factors: K1 =1,1; K2 =1,2; K’ =0,9

b Specification of items

*Calculation of G: (for gates made of steel)

g- averaged weight of the gate/unit (N/m2)

H- Height of gate (m); l0- Width of gate (m)

g was determined based on catalogs of gates or experimental formulas

*Calculation of Gd : depend on the designer

*Calculation of T1- Friction between gate and abutment:

*Calculation of T1- Friction between gate and abutment:

b Specification of items (cont.)

+ If gate slips against abutment:

T1 = f.Wof- Friction factor;

Wo- total water pressure acting on whole gate+ If gate moving is supported by wheels:

r- Radius of axle of wheel;

f- Sliding friction factor between axle and wheel;

f1- Rolling friction of wheel;

W: total water pressure on each of wheels;

*Calculation of T2- Friction at watertight components;

b Specification of items (cont.)

T2 = f2.W

f2- Friction factorW- Total water pressure acting on whole gate

In case of crest gate:

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In case of crest gate:

T2 = f2.a.γγγγha- width of watertight component;

h: water depth

2.3 Structural analysis of the gate

a Structure of the gate:

1 Principal beams; 2 Sub-beams; 3 Inner columns; 4 Border columns; 5 Braces; 6 Watertight surface plate

Method:

Divide the diagram of water pressure into n parts which has the same amount of total water pressure;

Position of each beam is the centroid of each part of

2.3 Structural analysis of the gate (cont.)

b Determination of principal beams:

Position of each beam is the centroid of each part of water pressure, correlatively.

A

B

C D b' d'

d b D'

b)

A

b d f A

f' d' b' a

a)

H/n H/n H/n H/n

a: In case of crest gate; b: In case of submerged gate

For crest gate:

yk- the distance from water surface to k-principal beam n- number of principal beams; H- water depth.

2

β +

=

2 2

2

a H

na

−

= β

a- the distance from water surface to crest of submerged gate

3 CALCULATION OF RADIAL GATE

Hydrostatic pressure;

Hydrodynamic pressure;

Weight of the gate;

Frictions;

3.1 Forces acting on the gate

Forces caused by floating objects

3.2 Necessary driving forces to open or close the gate

a General formulas:

Opening driving force:

Closing driving force:

To- force to win weight of the gate (G);

T1- force to win friction at the hinge;

T2- force to win friction at watertight components;

K1, K2, K’: Safety factors: K1 =1,1; K2 =1,2; K’ =0,9

l 3

W

b Specification of items

4

3 0

l

l G

2 l

R P f T

b Specification of items

*Calculation of G (To): Experimental formula of Berezinzki

(N)

F- area of watertight surface plate (m2)

*Calculating total water pressure acting on whole gate

4 F F

1500

2 2

1 INTRODUCTION

1.1 Definition

1.2 Classification

2 CALCULATION OF PLAIN GATE

2.1 Forces acting on the gate

2.2 Necessary driving forces to open/close the gate 2.3 Structural analysis of the gate

VALVES and GATES

2.3 Structural analysis of the gate

3 CALCULATION OF RADIAL GATE

2.1 Forces acting on the gate

2.2 Necessary driving forces to open/close the gate 2.3 Structural analysis of the gate

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