this presentation let us know about the types of gates used for dams

1. SPILLWAY CREST GATES
BY
G.MURALI MOHAN

2. →SPILLWAY GATE, ALSO CALLED STOP GATES, ARE
ADJUSTABLE GATES USED TO CONTROL WATER FLOW
IN RESERVOIR, RIVER, STREAM SYSTEMS.
→THEY ALSO ACTS AS BARRIER FOR THE STORAGE OF
ADDITIONAL WATER.
→BY THESE THE HEIGHT OF THE DAM WILL BE MORE
SUCH THAT LAND ACQUISITION WILL BE MORE.
→ GATES CAN BE PROVIDED TO ALL TYPES OF
SPILLWAYS EXPECT SIPHON SPILLWAY , BECAUSE
THE RAISE IN FLOOD LEVEL IS ALREADY SMALL
COMPARED TO THE OTHER TYPES OF SPILLWAYS
SPILLWAY CREST GATES

3. TYPES OF SPILLWAY GATES
 DRIPPING SHUTTERS OR PERMENENT FLASH BOARDS
 STOP LOGS AND NEEDLES
 RADIAL GATE ORTAINTER GATES
 DRUM GATES
 VERTICAL LIFT GATES OR RECTANGLE GATES

4. DRIPPING SHUTTERS OR PERMENENT FLASH BOARDS
 CONSISTSOFWOODEN PANELS
OF USUALLY 1.0-1.25m HIGH
 HINGEDAT BOTTOMANDARE
SUPPORTEDAGAINSTWATER
PRESSURE BY STRUCTS.THE
SHUTTERS FALLS FLAT ONTHE
CREST WHENTHE
DOWNSTREAM SUPPORTING
STRUCTSARETRIPPED. HENCE
THEY ARE NOT SUITABLE FOR
CURVEDCRESTS.
 THESE SHUTTERS CAN BE
RAISEDOR LOWERED FROM AN
OVER HEAD CABLEWAY OR A
BRIDGE.
 VARIOUS AUTOMATICGATES
WHICH DROP
THEMSELVESHAVE BEEN DESIG
-EDTHESE DAYS.

5. STOP LOGS AND NEEDLES
STOP LOGS
→ THEY CONSISTSOFWOODEN BEAMS
OR PLANKS PLACED ONE UPON THE
OTHER AND SPANNING IN THE
GROOVES B/WTHE SPILLWAY PIERS .
→THEY CAN BE ROMED EITHER BY
HAND ORWITH HOISTING MECHANISM.
ITTAKES LOT OFTIME FOR REMOVING
THEM,IFTHEY BECOME JAMMED IN
SLOTS.
→LEAKAGE BW LOGS ISA BIG PROBLE
-M HENCETHEYARE USED IN MINOR
WORKS.

6. NEEDLES
 NEEDLESAREWOODEN LOGS
KEPT SIDE BY SIDEWITHTHEIR
LOWER ENDS RESTING INA
KEYWAY ONTHE SPILLWAYAND
UPPER ENDS SUPPORTED BY A
BRIDGE.
 IT IS DIFFICULTTO HANDLETHESE
ATTHETIMEOF FLOW HENCE
THESARE NOT USEDON ANY
MAJORWORKS.
 THEY ARE SOMETIMESUSED FOR
EMERGENCY BULK HEADS,
WHERETHEY NEED NOT BE
REPLACED UNTILTHE FLOW HAS
STOPPED.

7. RADIAL GATE OR TAINTER GATES
 RADIAL GATESARE ROTARY GATES
CONSISTINGOF CYLINDRICAL
SECTIONS.
 THEY MAY ROTATEVERTICALLYOR
HORIZONTALLY.TAINTER GATESARE
AVERTICAL DESIGNTHAT ROTATES
UPTO ALLOWWATERTO PASS
UNDERNEATH.
 LOWFRICTIONTRUNNION BEARINGS,
ALONGWITHA FACE SHAPETHAT
BALANCES HYDROSTATIC FORCES,
ALLOWTHIS DESIGNTO CLOSE
UNDER ITS OWNWEIGHTAS A
SAFETY FEATURE.

8. DRUM GATES
 DRUM GATESARE HOLLOW
GATE SECTIONSTHAT FLOAT
ONWATER.THEY ARE PINNED
TO ROTATE UP OR DOWN.
WATER ISALLOWED INTO OR
OUT OFTHE FLOTATION
CHAMBERTOADJUSTTHE
DAM'SCREST HEIGHT.
 THESEARE DESIRABLETO
LONGER SPANS IN ORDER OF
40 OR SOAND MEDIUM
HEIGHTS OF 10 OR SO.

9. VERTICAL LIFT GATES OR RECTANGLE GATES
 RECTANGULAR GATESARE SPINNING HORIZONTALLY BWTHE
GROOVES MADE INTHE SUPPORTING SPILLWAY PIERS .
 THE GROOVE S ARE LINEDWITH ROLLED STEEL CHANNEL SECTIONS
OF APPROPRIATE SIZE , SO ASTO PROVIDE SMOOTH BEARING
SURFACE HAVING SUFFICIENT BEARING STRENGTHANDARE KNOWN
AS groove guides .
 RECTANGULAR GATES MOVE BW GROOVE GUIDES , AND CAN BE
RAISED OR LOWERED BY A HOISTING MECHANISM ATTHETOP.
 THE GATESARE MADEOF STEELOR CONCRETEORWOOD .
 THE FRICTIONAL RESISTANCE BW GATE AND DOWNSTREAMGROOVE
GUIDECAN BE REDUCED BY PLACING CYLINDRICAL ROLLERS BWTHE
BEARING SURFACE OFTHE GATE ANDTHE GUIDEGROOVES.
 LARGEVERTICALS LIFT GATES MAY BE COUNTER BALANCED BY A
COUNTERWEIGHT BEAM ,WHICH IS LOADEDTO BALANCE SELF
WEIGHT OFTHE GATE, SO HOISTING FORCE IS REQUIREDTO BALANCE
THE FRICTIONAL RESISTANCE .

10. THE SECTIONAL VIEW AND PLAN OF VERTIVAL LIFT GATE