10-CANAL SYPHONS



CANAL SYPHON

I.SITE SURVEY:

1 Site Survey to  be furnished as per check slip for CM &   Check Slip enclosed. CD works  with the following details. a i ) Report accompanying the Site survey ii ) HPs of canal & drain / river. b Site plan  with flow direction of canal & drain  with net levels  @ 10 mts interval & contours. c LS of drain / river. i) Covering 500 metres on U/S & D/S. (IS ; 7784 (Part I) : 1993)

ii) The LS with levels @ 10m to 20m interval with Cross sections

M.F.D.CALCULATIONS:

THE MFD MAY BE COMPUTED as per the following formula (as per the following formula)

IN DELTAIC AREAS :

Ryve's Formula Q = CM2/3

The catchment area shall be marked on the Topo Sheet for all the C.As more than 2.5 Sq. Km. If the C.A. is less than 2.5 Sq.km.,

the C.A. is to be traversed on ground and to be furnished. 

The MFD may be computed as per the following formula.

IN UPLAND AREAS:

Dicken's Formula, Q = CM 3/4 Q =  Discharge in Cusecs. M = Catchment area in sq.miles

ii) The LS with levels @ 10m to 20m interval with Cross sections of drain on U/S, D/S @ centre line, 10 m, 25m, 50m,100m, & @ 100m interval beyond for a length of 500m.

iii) The Cross section  levels shall be @ 3m to 5m interval in the gorge portion and 10m intervals  in the flanks extended upto MFL touching the ground.

iii) For deltaic catchment areas of Krishna & Godavari, the formula shall be Ryve's formula adopting 'c' value as per Mitra Committee Report for Upland & Deltaic Catchments.

Observed MFD may be computed from the observed MFL and shown on the LS & CSs.

Bore hole data / TPs upto Hard strata or for min. depth of 2m for shallow foundations & upto 1/3rd embedment depth below maximum scour depth, along the Centre Line @ suitable intervals depending upon the importance of the structure with minimmum

5 Nos. of TPs  covering both the Drain & Canal @ centre, U/S & D/S sides.

2.DESIGN :

Note on Principles of Design, the assumptions made & the general features of the structure.

HYDRAULIC DESIGN :

1. MFL computations adopting Step by Step method.

2. (a) Design of ventway for the Canal with minimum 1200 mm height in case of barrel and 900 mm dia in case of pipe conduit, limiting allowable velocity.

(b) For small discharge of canal, Pipes can be proposed limiting the velocity with minimum 900 mm dia.

3. Design of Tail channel & Approach channel keeping in view the Lacey's Formula for Wetted perimeter & velocity limits depending on stratification.

4. Transition lengths on U/S & D/S of drain.

5. TEL calculations for the canal  considering Unwins Formula and eddy loss   coefficients as per IS code along with flow diagram with dimensions and levels.

6. Scour depth calculations  of drain.

R= 1.34 (q2/f)1/3 with relevant factor of safety.

a) Design of Slab  /  RCC Box for critical load combinations.(IS : 3370 - 1965 part I & part II, )

b) Design of Head wall on U/S & D/S by adopting TVA procedure / Coulomb's Theory / Rankine's Theory with a top width of 500mm.      (IS : 3370 - 1965 part I & part II,)

c) In case the structure is clubbed with Single lane / Double lane bridge refer guidelines for Bridges(TVA Hand Book)

7. Uplift calculations for the floor of the barrel and U/S & D/S side aprons 8. Exit gradient calculations

9. Proposal Sketch.

G E = (H/d)x [1/(π√λ)] ; Where λ = [1+ √(1+α2)]/2 ; α = b/d

ii) SUB STRUCTURE

I a) CONVENTIONAL TYPE  :-

1. Design of Pier : Minimum thickness of pier shall be 1 m.

2. Design of Abutment

3. Abutment and Pier foundations shall be Isolated Footing / RCC raft as the case may be.

I  b) RCC BOX  :-

RCC box  (It is preferable to provide Inspection Chambers at 50 m interval in case of lengthy barrels.)

I  c) PIPE   :-

Pipe details

II  Design of Wing walls & Return walls both on U/S & D/S of drain - The walls adopting TVA procedure / Coulomb's Theory / Rankine's Theory with a top width of  500mm.

III  Tabulation of stress table :- A consolidated stress table has to be furnished indicating the stress in concrete & stress on soil for the  Head wall, Abutment, Piers, Wings & Returns.

IV  Unless otherwise mentioned, Minimum Grade of concrete for PCC shall be M10 and for RCC M20.
3.MISCELLANEOUS ITEMS :-

a) Water stops

b) Weep holes in the Retaining walls

c) Bearings

d)  Expansion , Contraction & Construction Joints

e) Bell Mouth on U/S side

f) Cut & Ease waters

DRAWINGS

a) General Layout on net level plan duly showing contours.

b) General Plan, Sectional Elevation & End View - Plan indicating Half plan @Top & Half plan @ bottom &  Sectional elevation along the LS of the drain & End view  along the cross section of  the drain

c)  Wall Sections,  RCC Details & Details of miscellaneous items. (Scale : 1:50 (or) 1:100 for sections)

The Drawings shall contain amade, TPs,Specifications, HPs of canals, Hydrology  of the drain,Bar bending schedule, Stress table etc.(Scale : 1:25 (or) 1:20/1:10 for RCC details.)

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