UTS (TYPE II AQUEDUCTS) / PIPE UTS
Site Survey to be furnished as per check slip for CM & CD works with the following details.
i) Report accompanying the Site survey
ii ) HPs of canal & drain / river.
iii).Site plan with flow direction of canal & drain with net level at 10m intervals & contours( IS:7784 (Part I) : 1993)
LS of drain / river : i)Covering 500 metres on U/S & D/S.
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.
iv)The catchment area shall be marked on the Topo Sheet for all the CAs 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:
1.IN UPLAND AREAS:
Dicken's Formula, Q = CM3/4
Q = Discharge in Cusecs.
M = Catchment area in sq.miles
C = Coefficient depending on Catchment area. CA upto 1 Sq.mile.
C=1400 CA from 1 Sq.mile to 30 Sq.miles
C=1200 CA more than 30 Sq.mileC=1060
(2) IN DELTAIC AREAS :
Ryve's Formula Q = CM2/3
C = 1000 for Q more than 500 cusecs C = 750 for Q less than 500 cusecs
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 maybe 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.Also the Safe Bearing Capacity of foundation strata be furnished(Table I & II of APERL for test results of foundation soils enclosed., IRC 78:2000.)
Note on Principles of Design, the assumptions made & the general features of the structure
HYDRAULIC DESIGN :
1. MFL computations adopting Step by Step method. Design of Small Dams by USBR. IS:7784 (Part 2 / section1):1995, IS : 7784 (part I) - 1993
2. (a) Design of ventway for the Drain / river in UT / Pipe UT limiting allowable velocity.Pipe conduit with minimum of 900mm dia and barrel of 1.2m minimum height may be provided.( IS 458 -1988, IS :783 - 1985 IS : 7784 (part - I) - 1993)
(b) For small discharge of Drain, Pipes can be proposed limiting the velocity.( IS ; 7784 (part 2/sec1) : 1995 )
3. Design of Tail channel & Approach channel keeping in view the Lacey's Formula for Wetted perimeter & velocity limits depending (IS : 7784 (part I) 1993)
4.Lift Wall on D/S side of the structure may be avoided.
5. Transition lengths on U/S & D/S of drain.( IS ; 7784 (part 2/sec1) : 1995)
6. TEL calculations for the Drain considering eddy loss coefficients as per IS code along with flow diagram with dimensions and levels(IS : 7784 (part I) 1993)
7. Scour depth calculations of drain.R=1.34 (q2 / f)1/3 with relevant factor of safety.( IS : 7784 (part - I) - 1993)
8. Uplift calculations for the floor of the barrel and U/S & D/S side aprons( IS : 7784 (part - 2 / sec 2) - 2000)
9. Exit gradient calculations GE = (H/d)x [1/(π√λ)] ; Where λ = [1+ √(1+α2)]/2 ; α = b/d;(IS : 7784 (part - I) - 1993, CBI Publication 12)
STRUCTURAL DESIGN :
i) SUPER STRUCTURE
a. Design of Slab under canal trough & under earth bank / RCC Box for critical load combinations(IS : 3370 - 1965 part I & part II,
IS : 7784 (Part 2 / sec I) : 1995)
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.(TVA Hand Book)
ii) SUB STRUCTURE
I a) CONVENTIONAL TYPE :-
1. Design of Pier under canal trough & earth bank
2. Design of Abutment under canal trough and earth bank. (TVA Hand Book,(IS - 7784 (part 2 / sec- I): 1995.IRC - 78- 2000 ; SP - 16 ;)
3. Abutment and Pier foundations shall be Isolated Footing / RCC raft as the case may be
4. Design of Holding down bolts where ever applicable.
b) RCC BOX :-
RCC box under canal trough, earth bank and Head wall.(IS : 7784 (Part 2 / sec I) : 1995)
I c) PIPE UTs :-
Pipe details (IS 458 : 1988 , IS 783 - 1985(TVA Hand book)
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 on concrete & stress on soil forthe Head wall, Abutment, Piers, Wings & Returns.
IV Unless otherwise mentioned,the minimum grade of PCC shallbe M10 Grade and the minimum grade of RCC shall be M20 grade.(IS - 456 : 2000)
4.MISCELLANEOUS ITEMS :-
a) Water stops (IS : 7784 (part I) :1993)
b) Weep holes in the Retaining walls( IS : 7784 (part I) :1993)
c) Bearings IS : 7784 (part I) :199(IS : 3370 (part I) - 1965,)
d) Expansion , Contraction & Construction Joints ( IS : 7784 (part 2/Section 3) :1996)
e) Bell Mouth on U/S side
f) Cut & Ease waters
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.(Scale : 1:50, 1:100 (or) 1:200)
c) Wall Sections, RCC Details & Details of miscellaneous items.(Scale : 1:50 (or) 1:100 for sections)
The Drawings shall contain assumptions made, TPs,Specifications,HPs of canal, Hydrology of the drain,Bar bending schedule, Stress table etc.(Scale : 1:25 (or) 1:20/1:10 for Rcc details.)