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GOVERNMENT OF ANDHRA PRADESHIRRIGATION & CAD DEPARTMENT
GENERAL PRINCIPLES OF CANAL LINING
Er.B.Lakshmana Rao B.Tech., .B.A., F.I.E.,
Chief Engineer, CDO & SRISAILAM PROJECT Hyderabad.09440817277
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FUNCTIONS OF LINING
SEEPAGE CONTROLPREVENTION OF WATER LOGGINGINCREASED HYDRAULIC EFFICIENCYINCREASED RESISTANCE TO
EROSION/ABRASIONREDUCTION IN CROSS SECTION AREASMALLER STRUCTURESLOW OPERATION AND MAINTENANCE COST
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REQUIREMENTS OF LININGECONOMYSTRUCTURAL STABILITYSTRENGTH AND DURABILITYREPAIRABILITY AND EASY MAINTENANCEMAXIMUM HYDRAULIC EFFICIENCYIMPERMEABILITYRESISTANCE TO EROSIONABILITY TO PREVENT WEED GROWTHRESISTANCE AGAINST BURROWING
ANIMALSREASONABLE FLEXIBILITY
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TYPES OF LINING
RIGID LININGSTONE PITCHED LININGBURNT CLAY TILE/BRICK LININGPRECAST CEMENT CONCRETEIN-SITU CEMNT CONCRETE LININGSTONE MASONRY LININGSOIL CEMENT LININGSHOTCRETE LININGASPHALTIC CEMENT/CONCRETE LINING
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TYPES OF LINING
BITUMINOUS / ASPHALTIC FELT LININGFIBRE REINFORCED PLASTIC TISSUE
ASPHALTIC MEMBRANECOMPOSITE MEMBRANE/RUBBER LININGFLEXIBLE LINING
GEOMEMBRANE HDPELDPEPVC
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FREE BOARD
FREE BOARD IS VERTICAL DIFFERNCE BETWEEN F.S.L OF CANAL AND TOP OF LINING
CANAL DISCHARGE FREE BOARD
cumecs metres
> 10 0.75
3 – 10 0.60
1 – 3 0.50
< 1.0 0.30
< 0.1(water courses) 0.15
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LIMITING VELOCITY
STONE PITCHED LINING - 1.5m/sec
BRICK LINING - 1.8m/sec
CEMENT CONCRETE LINING – 2.7m/sec
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THICKNESS OF C.C. LININGThe thickness of concrete lining may be adopted
from Table-I of IS 3873-1993 depending upon the canal discharge and depth of water.
Capacity Depth of Thickness
of canal Water of Lining
(cumecs) mtrs mm
0 – 5 0 – 1 50 – 60
50 – 100 1-2.5 60 – 75
50-200 2.5-4.5 75 – 100
200-300 4.5-6.5 90 – 100
300-700 6.5-9.0 120- 150
Note: Hydel canal should have a greater thickness
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SUB GRADE
Sub grade should be prepared, dressed and rolled true to level and according to the cross section of the canal to form a firm compacted sub grade for the lining.
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PREPARATION OF SUB GRDE
Expansive soilsConsisting of rockConsisting of soil
Sandy reachesOther than sandy reaches
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UNDER DRAINAGE OF LINED CANALS
Drainage arrangements should be such that the pressure on lining does not increase beyond the safe limit
CONDITIONS OF WATER TABLEBELOW CANAL BED LEVELBETWEEN CANAL B.L. AND F.S.L.ABOVE CANAL F.S.L.
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TYPES OF SUB GRADE
FREE DRAINING – Gravel with sand/Sandy soil whose ‘k’ is 10-4cm/sec
POOR DRAINING – Very fine sand / admixture of sand / silt / clay
whose ‘k’ is 10-6 to 10-4cm/secPRACTICALLY IMPERVIOUS –
Homogeneous clays
whose ‘k’ is 10-6 cm/sec
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METHODS OF UNDERDRAINAGEPosition of
Water Table
Free Draining Poor Draining Practically Impervious
Below Canal B.L. 150-200 th. well defined filter
600 thick Sand/Murram/
Pervious material
Between C.B.L And F.S.L.
150-200 th. well defined filter
150-200 th. well defined filter
600 thick Sand/Murram/
Pervious material
Above Canal F.S.L.
150-200 th. well defined filter
600 thick Sand/Murram/
Pervious material
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PRESSURE RELIEF ARRANGEMENTSCase -Water table below canal B.L. :
No pressure relief arrangements are required
Case –Water table between Canal B.L. and F.S.L.:Bed : Longitudinal and transverse drains with
pressure relief valvesSides : Pressure relief valves in pockets.
Case – Water table above canal F.S.L.: Same as above of Case
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LONGITUDINAL DRAINSTRANSVERSE DRAINS
150MM DIA AC/ PVC PIPES12 DIA HOLES 100HOLES PER METRE LENGTHPARALLEL ROW OF HOLES SHALL BE
STAGGEREDSPACING 10m c/cPRESSURE RELIEF VALVES AT SIDES
1 FOR EVERY 100 SqM
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ANTI - SALT TREATMENT
SALT CONTENT – 1%SODIUM SULPHATE – 0.36% SUB GRADE SHOULD BE COVERED
WITH 2mm THICK BITUMEN LAYER BY SPRAYING AT 2.35Kg/sqmTO GET GOOD BOND BETWEEN SOIL AND BITUMEN CRDE OIL @ 60.5lit SHOULD BE SPRAYED OVER IT WELL IN ADVANCE WHEN SUB GRADE IS DRY, CLEAN AND FREE FROM DIRT
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SURFACE DRAINAGE
THE TOP OF THE SIDE LINING CONCRETE SHOULD BE KEYED INTO THE SUBGRADE BOTH IN CUTTING AND EMBANKMENT BY TAKING IT HORIZONTALLY FOR A WIDTH OF ABOUT 300mm. THIS KEY WOULD PREVENT DIRECT ENTRY OF SURFACE RAIN WATER BEHIND THE LINING.
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SEQUENCE OF LINING
IT IS PREFERABLE TO PLACE CONCRETE ON SIDES FIRST.
THIS WILL PREVENT THE BED FROM GETTING SPOILED BY SUBSEQUENT OPERATIONS
THE PANEL WIDTH SHOULD VARY 2-3 METRES, IN NO CASE IT SHOULD NOT BE >3M.
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CURING
THE LINING SHOULD BE CURED FOR AT LEAST 28 DAYS, SUBSEQUENT TO LAYING OF CONCRETE LINING AFTER A PERIOD OF 12 HOURS.
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CANAL LINING IN EXPANSIVE SOILS
EXPANSIVE SOILS: BED AND SIDE SLOPES OF CANAL IN CUTTING AND EMBANKMENT WHEN IN CONTACT WITH WATER SWELL
THEY EXERT A PRESSURE OF 50-300 KN/Sqm OR MORE
BLACK COTTON SOILS AND A WIDE RANGE OF EXPANSIVE SOILS ARE SEEN ACROSS INDIA
SWELLING PRESSURE AND FREE SWELL INDEX TESTS SHALL BE DONE AS PER IS 2720:1977( PARTS 40 AND 41 )
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COHESIVE NON-SWELLING SOILS
PROPERTY ON COHESIONNON EXPANDINGLOW PLASTICITY WITH LIQUID LIMIT
NOT>50%, PLASTICITY INDEX NOT>30
CNS SOILSCLAYEY SOILSSILTY CLAYSANDY CLAYGRAVELLY SANDY CLAY
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THICKNESS OF CNS LAYER
(For canal Discharge more than 2cumecs)
Swell pressure Thickness
kN/sqm cm (min)
50 – 150 75
150 – 300 85
300 – 500 100
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CONSTRUCTION PROCEDURE
CANAL IN CUTTING
Proper moisture to be added after spreading CNS material in 150mm thick layers and compacted and after getting the required thickness, the surface should be trimmed.
Then canal lining shall be taken up.
In deep cuts, the CNS layer should be provided upto GL. The thickness above canal prism may be 150-200mm, 1000mm above F.S.L of canal
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CONSTRUCTION PROCEDURE
CANAL IN EMBANKMENTProper moisture should be added to CNS soil and
expansive soil surfaceExpansive soil and CNS Soil above GL should be
compacted simultaneously in layers with appropriate equipment to ensure proper density
A rock toe with inverted filters may be provided at either end of canal bank
The thickness of CNS layer on rear slopes may be 150-200mm provided simultaneously with expansive soil
and proper turfing is to be provided to protect slopeCNS layer below sand blanket at rock toe portion shall be
provided
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TESTS FOR LININGTESTS FOR LINING(NON – DESTRUCTIVE REBOUND HAMMER TEST))
TO TEST THE EFFECTIVENESS OF VIBRATION
• PERMEABILITY
• STRENGTH
OF CONCRETE CORES AT SUITABLE PLACES FROM THE SIDES OF CANAL AS WELL AS FROM THE BED CANAL CONCRETE SHALL BE TAKEN
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LIST OF B.I.S. CODES
1. Code of practice for design of cross section of lined canals – IS – 4745:1968
2. Guidelines for lining of canals in expansive soils -- IS – 9451:1994
3. Laying cement concrete lining on canals - IS – 3873:1993
4. Under drainage of Lined canals - IS – 4558 :1983
5. Design of Lined canals and guidance for Selection of Lining - IS –10430:1982
6. Pre cast cement concrete tiles for canal lining - IS – 10466 : 1991