FOREBAYDESIGN OF FOREBAY
PROJECTABC PROJECTRIVERABC RIVERREGIONPAKISTANDESIGN ENGINEERM.
ASIF
INPUT
-BASIC DATAMinimum diverted water - HeadraceQH=1.20m3/sDesign
discharge - PenstockQP=3.00m3/s( = Peak discharge)
-INFLOWSLength of headraceLH=5000.0mDiameter/Bed width of
headraceDH2.50mDepth of flow in headracedH1.18mX-sectional area of
flowAH=2.94m2Velocity in headracevH=0.41m/sVolume of
headraceVH=14710m3Time of travel (upto forebay)tH=12258sec
-OUTFLOWS
Length of penstockLP=500.0mDiameter of
penstockDP=1.00mX-sectional area of flowAP=0.79m2Velocity in
penstockvP=3.82m/sVolume of penstockVP=393m3Time of travel (upto
turbines)tP=131sec
-PEAKING TIME
Peaking timeTPK=0.1hrsNon-peaking timeTN-P=23.9hrs
Volume of water required for peakingVPK=1080m3
-FOREBAY DIMENSIONS
Width of forebay (at start)WFs=20.0
AID02: AID02:AssumedmWidth of forebay (at end)WFE=12.6mLength of
forebayLF=23.1mDepth of forebay (including
freeboard)dF=8.0mFreeboard in forebayF.B=1.5m
Slope for vertical transition
ASIF: ASIF:Enter "0" for vertical dropz=1.01v : zhLength of
vertical transitionLVT=7.5mx of vertical transitionxVT=5.3m
SIDE WALLS GEOMETRYWidth of side walls at topwt=0.5mWidth of
side walls at bottomwb=0.8m
Extension of bottom slab at each endws=0.8mThickness of bottom
slab at each endtsE=1.0mThickness of bottom slab in
centertsC=0.5mLength of thicker bottom slab
ASIF: ASIF:From structural designlb=10.0mshould be < 10
TRANSITION LENGTH (PLAN VIEW)Diameter/Bed width of
headraceDH=2.5mTransition angle=15degree
Transition lengthRef: L.W. Mays
Transition length - horizontal (required)LHT=32.7mTransition
length (provided)LHT=33.0m
-CONCRETE VOLUME (FOREBAY STRUCTURE)
Thickness of top slabtt=0.3m
PCC blinding layer (0.1m thick)YESTop slabNO
X-sectional area of top slabAts=0.00m2
X-sectional area of bottom slabAbs=22.60m2
X-sectional area of side wallsAsw=12.35m2
Total x-sectional areaAXS=34.95m2
Concrete volume of main structureVms=808.8m3
Concrete volume of u/s transitionVut=576.68m3(approx)
Concrete volume of spillwayVsp=128.99m3(approx)
Total concrete volume of forebayVTF=1514.51m3
PCC quantity in blinding layerCPcc=53.69m3
-HEADLOSSESL-SECTIONX-SECTIONPLAN0.01451.30.01452.30.00.0FRICTION
LOSS0.01452.30.31460.323.120.0Friction headloss
(Manning)0.31460.30.81460.30.81460.30.81452.310.010.0Flow
areaA=130.00m20.81452.320.81452.313.110.0Wetted perimeterP=33.00m
23.91452.120.81460.3Hydraulic radiusR=3.94m
23.91460.321.31460.3-0.5-0.5Flow
velocityV=0.023m/s24.41460.321.61452.323.620.524.71452.122.41452.3Friction
headloss in
forebayhf=4.5E-07m24.71451.122.41451.3-0.8-0.813.91451.221.61451.323.920.8ENTRANCE
LOSSRef: Mosonyi13.41451.710.81451.3K =
ASIF: ASIF:K = 0.10 to 0.200.1011.31451.710.31451.8Entrance
headlosshLE=0.002m10.81451.211.31451.80.01451.310.81451.3GATE SLOT
LOSS-0.81451.37.41458.8-0.81452.317.41458.8C
WhereRef: Mosonyi7.41457.48.31458.8"Vol-I: page #
530"17.41457.413.31458.8and Weisbach
coefficient0.31460.38.31457.4Velocity (just before the
slots)vin=0.8m/s24.41460.313.31457.4Width of entrance
flumeB=2.50mDepth of entrance flumeh=2.50m
Width of gate sloteg=0.30m Depth of gate slotdg=0.10m
if d > 0.2e then y* = 0.2e& if d
