07-CANAL DROPS



CANAL DROPS

1.SITE SURVEY:

Site Survey to be furnished as per check slip for Drops with the following details

i)Report accompanying the Site survey ii)H.P.s of canal.

Site plan  with flow direction of canal  along with net levels @ 10m intervals & contours.
LS of  canal:

i)covering  500 meters on U/S &D/S with levels @10m inteval.

Bore hole data /TPs upto Hard strata or for min. depth of 2m along the Centre line @ suitable intervals depending upon the importance of structure with minimum 2 Nos covering Canal @ centre & D/S sides.(Table I & II of APERL for test results of foundation soils enclosed. IRC 78 : 2000)

2.DESIGN :

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

HYDRAULIC DESIGN

1.Fixation of crest ,Throat width  of drop wall, Length of stilling basin and other components of stilling basin.(Manual on canal falls,I.S:4997 )

2.Design of Drop wall.(Text Book of Irrigation Manual by W.M.Ellis. IS : 7784 (part - I) - 1993 IS : 7784 (part - I) - 1993)

3.Transitions lengths on U/S & D/S .

4. Scour depth calculations.

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

5. Checking of thickness of apron(Publication No.12 of CBIP )

6. Exit gradient calculations(Publication No.12 of CBIP)

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

7. Proposal Sketch

STRUCTURAL DESIGN

a. Design of Body wall ( Drop wall)(As per IS: 456-2000 and IS: 33701965)

b. Design of stilling Basin. (IS: 4997- 1995 )

c. Design of wing walls &Return walls both on U/S &D/S of canal - The walls are to be designed adopting TVA procedure/ Coulomb's Theory / Rankine's Theory with a top width of 500mm. 
HYDRAULIC (TVA Hand book , IS 1904-1966))

d)  Tabulation of stress table :- A consolidated stress table has to be furnished indicating the stress on concrete & stress on soil for the Body wall& Wings 

e)Minimum grade of PCC shall be M10 Grade,unless otherwise specified.(IS-456:2000)

F)Wearing coat over Body wall & stilling basin minimum grade shall be CC M20 grade,unless otherwise specified. ( IS-456:2000)

3.MISCELLANEOUS DETAILS:-

a)Water stops(IS:7784-1993 )

b)Weep holes in the Retaining walls(IS:7784-1993 )

c) Expansion , Contraction & Construction Joints(IS : 3370 (part I) - 1965)

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 canal & End View along the cross section of the canal.(Scale : 1:50, 1:100, (or) 1:200)

c)Wall Sections & Details of miscellaneous items.(i)Scale : 1:50,(or) 1:100 for sections ii)Scale: 1:25(or)1:20 for Rcc details)

The drawings shall contain assumptions made,TPs,Specifications,HPs of canal,Bar bending schedule where-ever applicable, Stress table et

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