Canal lining

09-12-2011 NAC, HYDERABAD 1

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

[email protected]


CANAL LINING


FUNCTIONS OF LINING

SEEPAGE CONTROLPREVENTION OF WATER LOGGINGINCREASED HYDRAULIC EFFICIENCYINCREASED RESISTANCE TO

EROSION/ABRASIONREDUCTION IN CROSS SECTION AREASMALLER STRUCTURESLOW OPERATION AND MAINTENANCE COST


REQUIREMENTS OF LININGECONOMYSTRUCTURAL STABILITYSTRENGTH AND DURABILITYREPAIRABILITY AND EASY MAINTENANCEMAXIMUM HYDRAULIC EFFICIENCYIMPERMEABILITYRESISTANCE TO EROSIONABILITY TO PREVENT WEED GROWTHRESISTANCE AGAINST BURROWING

ANIMALSREASONABLE FLEXIBILITY


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


TYPES OF LINING

BITUMINOUS / ASPHALTIC FELT LININGFIBRE REINFORCED PLASTIC TISSUE

ASPHALTIC MEMBRANECOMPOSITE MEMBRANE/RUBBER LININGFLEXIBLE LINING

GEOMEMBRANE HDPELDPEPVC


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


LIMITING VELOCITY

STONE PITCHED LINING - 1.5m/sec

BRICK LINING - 1.8m/sec

CEMENT CONCRETE LINING – 2.7m/sec


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


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.


PREPARATION OF SUB GRDE

Expansive soilsConsisting of rockConsisting of soil

Sandy reachesOther than sandy reaches


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.


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


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



Pervious material

Above Canal F.S.L.



Pervious material


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


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


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


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.


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.


CURING

THE LINING SHOULD BE CURED FOR AT LEAST 28 DAYS, SUBSEQUENT TO LAYING OF CONCRETE LINING AFTER A PERIOD OF 12 HOURS.


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 )


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


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


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


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


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


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


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Canal lining

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