spillway ratings and stability design procedures __________________________ sites 2005 integrated...
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SPILLWAY RATINGS SPILLWAY RATINGS andand
STABILITY DESIGN PROCEDURESSTABILITY DESIGN PROCEDURES
____________________________________________________SITES 2005SITES 2005
INTEGRATED DEVELOPMENT ENVIRONMENTINTEGRATED DEVELOPMENT ENVIRONMENTfor
WATER RESOURCE SITE ANALYSIS
OBJECTIVE
Provide understanding of:• Principal spillway rating
• Auxiliary spillway rating
• Permissible velocity approach
• Allowable stress approach
• Cover discontinuities
The first elevation entry in the table must correspond to the spillway crest elevation. The first discharge entry must be zero, and the subsequent discharge entries must increase with increasing elevation.
Inlet
Conduit
EXAMPLE HELP
the rating for the auxiliary spillway may be entered at the structure table
AUXILIARY SPILLWAY RATINGAUXILIARY SPILLWAY RATING
FEATURESFEATURES
• VARIABLE FLOW RESISTANCEVARIABLE FLOW RESISTANCE (by reach)
• MIXED VEGETAL AND NON-VEGETAL MIXED VEGETAL AND NON-VEGETAL flow resistance
• SEEKS HYDRAULIC CONTROL SECTIONSEEKS HYDRAULIC CONTROL SECTION
Auxiliary Spillway ProfileAuxiliary Spillway Profile
InletNaturalGround
ConstructedInlet Channel Constructed
Exit Channel
Exit Natural Ground
Tie
Sta
.
X
SPILLWAY PROFILE
Avoid short steep slopes between mild slopes!Avoid short steep slopes between mild slopes!
The program identifies the hydraulic control as the upstream end of the first reach downstream of the crest that flows supercritical at the discharge in question. Reach length is not checked. Therefore, short steep reaches that may be submerged by mild slope reaches downstream may cause improper rating.
CCII = 5.6 = 5.6
n = 0.04n = 0.04
AUXILIARY SPILLWAYAUXILIARY SPILLWAYSTABILITY ANALYSISSTABILITY ANALYSIS
SITESSITES
SITESSITES
STABILITY ANALYSISSTABILITY ANALYSIS
TECHNOLOGY OPTIONSTECHNOLOGY OPTIONS• PERMISSIBLE VELOCITYPERMISSIBLE VELOCITY• ALLOWABLE STRESSALLOWABLE STRESS
COMPUTATIONAL OPTIONSCOMPUTATIONAL OPTIONS
• ENTER BED WIDTHENTER BED WIDTH - COMPUTE STRESS LEVEL• ENTER ALLOWABLE STRESS LEVEL ENTER ALLOWABLE STRESS LEVEL - COMPUTE BED WIDTH
VEGETAL EROSION PROTECTIONVEGETAL EROSION PROTECTION
PERMISSIBLE VELOCITY PERMISSIBLE VELOCITY
COVER SLOPE %
EROSION RESISTANT
EASILY ERODED
Bermudagrass 0-55-10>10
876
654
Kentucky Bluegrass0-55-10>10
765
543
Weeping Lovegrass 0-5 3.5 2.5
(ft/s)(ft/s)
VEGETAL COVER FACTORVEGETAL COVER FACTORused to compute
EFFECTIVE STRESSEFFECTIVE STRESS
COVERCOVER FACTOR
Bermudagrass
Kentucky Bluegrass
Weeping Lovegrass
0.9
0.87
0.5
CF
AH 667TP 61
ORDINARY FIRMORDINARY FIRMLOAMLOAM
SILT LOAMSILT LOAM
SANDY LOAMSANDY LOAM
EROSION RESISTANT
EASILY ERODED
FLOW DEPTH, ft
AV
ER
AG
E V
EL
OC
I TY
, ft/
s
MAINTENANCE CODEMAINTENANCE CODE
1 - UNIFORM COVER OR SURFACE1 - UNIFORM COVER OR SURFACE
2 - MINOR DISCONTINUITIES2 - MINOR DISCONTINUITIES
3 - MAJOR DISCONTINUITIES3 - MAJOR DISCONTINUITIES
EFFECTIVE STRESSEFFECTIVE STRESS
• Maintenance code effectMaintenance code effect
e= ds(1-Cf) (ns/n)2
If MC=2, Cf0
If MC=3, Cf0 and n ns
AUXILIARY SPILLWAYAUXILIARY SPILLWAYSTABILITY ANALYSISSTABILITY ANALYSIS
SITESSITES
SUMMARYSUMMARY
• BASED ON PEAK OF SDHBASED ON PEAK OF SDH• APPLIED TO EXIT CHANNELAPPLIED TO EXIT CHANNEL• VELOCITY OR STRESS calculationsVELOCITY OR STRESS calculations• COMPUTE V, COMPUTE V, ee, or BED WIDTH, or BED WIDTH• MAINTENANCE CODE for stress MAINTENANCE CODE for stress calculationscalculations
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