design of stepped spillway

7/29/2019 Design of Stepped Spillway

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A Stepped Spillway Preceded by aSupercritical Flow Channel

aro u y rau c ng neer

Sacramento District Corps of Engineers

June 14, 2011

US Army Corps of Engineers

BUILDING STRONG


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-

BUILDING STRONG2


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BUILDING STRONG3


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Dam SafetyDam Safety

Capacity

Capacity

Flood Protection D/S Levee Capacity Flood Protection D/S Levee Capacity

160,000 cfs Lower Outlets 25,000 cfs160,000 cfs Lower Outlets 25,000 cfs

BUILDING STRONG


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Main DamMain Dam

Structure

Structure

illwillwChute

Chute

pproacChannel

pproacChannel

BUILDING STRONG


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Chute

Chute

Stepped

Chute

Stepped

ChutetillintillinBasin

Basin

BUILDING STRONG


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CORPS CONSTRUCTED DAM IN 1950S

DAM TURNED OVER RECLAMATIONHYDROPOWER AND WATER SUPPLY

RECENTY HISTORY CORPS

REDUCTION CAPABILITY OF DAM;

BUILDING STRONG


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CORPS MODS TO MAIN DAM PROJECT

USBR FUSE PLUG SPILLWAY INCL

DAM EMBANKMENT AND FOLSOM

CORPS BEST ALT FOR MODS PROJ

AUX SPWY WITH SUBMERGED GATE;SAME ALIGNMENT AS FUSE PLUG

BUILDING STRONG


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PMF Q = 320K CFS; FC DESIGN Q =

LIMITED SPACE FOR AUXILIARY; 6 34 23

SUBMERGED (BY 100 +) TAINTER;

CHUTE WIDTH = 169; HIGH UNIT Q

q = 800 (DES) AND 1900 (PMF) CFS/FT

BUILDING STRONG


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2100 LONG CONCRETE LINED,

BASED ON ROCK LINE RESULTED IN

V = 67 FPS FOR 135k CFS & 80 /SEC

320OF CHUTE

BUILDING STRONG


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Stepped Spillway inSupercritical Spillway Chute

(135,000 cfs)

(320,000 cfs)

c s

78 ft/sec - Max

,

84 ft/sec - Max

3.7 - Froude #

10.8 ft - Depth

. -

23.2 ft - Depth

BUILDING STRONG11


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STEPPED CHUTE U/S OF A STILLING

CONVENTIONAL PARABOLIC DROP /

COMPARATIVE COSTS.

BASED ON A PARABOLIC DROP EQ.

STEP HEIGHTS VARY FROM ABOUT0.8 AT U/S END TO 3 (MOST ARE 3)

BUILDING STRONG


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Stepped Spillway inSupercritical Spillway Chute

Y=0.02*X+0.000472406*X2S=0.02

1V:2.483555158H

Stilling

BUILDING STRONG13


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INTERACTION OF STEPS AND BASIN

ABRASION OF STEPS NEED FOR ADDED AERATION

LOADINGS FOR STRUCTURAL DESIGN

BUILDING STRONG


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MODELS HELPADDRESS CONCERNS

USBR 1:48 SCALE PHYSICAL MODEL

USBR CFD (FLOW-3D) ALDEN LABS CHECK OF CFD RESULTS

BUILDING STRONG


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BUILDING STRONG16


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BUILDING STRONG17


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BUILDING STRONG18


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BUILDING STRONG


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SAFL 1:26 SCALE MODEL

BUILDING STRONG20

= ,


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BUILDING STRONG21

Q = 135,000 cfsQ = 135,000 cfs


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Q = 322,000Q = 322,000 cfscfs

BUILDING STRONG22


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Profile of Stepped Spillway

340

Velocit Profile

280

300

320

@ Step 0 Velocity Profile@ Step 32

240

260

tio

n,

feet

V l i Pr fil

180

200Eleva

@ Step 61

120

140

160

BUILDING STRONG23

31+00 32+00 33+00 34+00 35+00 36+00 37+00 38+00 39+00 40+00

Station, feet


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135 000 CFS VELOCITIES10

12

8

Step 0_5

Step 0_4

Step 0_3

Step 0_2

Step 0_1

6

Depth

(ft)

ep _

Step 32_4

Step 32_3

Step 32_2

Step 32_1Step 61_5

4

Step 61_4

Step 61_3

Step 61_2

Step 61_1

0

2

BUILDING STRONG

35 45 55 65 75 85 95 105 115

Velocity (ft/sec)


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,25

Step 0_5

Ste 0 4

20

_

Step 0_3

Step 0_2Step 0_1

Step 32_5

Step 32_4

15

Depth

(ft) Step 32_3

Step 32_2

Step 32_1

Step 61_5

Step 61_4

10ep _

Step 61_2

Step 61_1

0

BUILDING STRONG

40 50 60 70 80 90 100 110 120 130 140

Velocity (ft/sec)


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SAFL ENERGY LOSS

Discharge

EnergyLoss

SpillwayEnergy Loss

Stilling Basin

Energy Loss

22,508 93% - -

- -

113,049 83% - -

,158,249 78% - -

BUILDING STRONG26

301,710 67% 34% 33%


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ENERGY LOSS

CONFIRMATIONS

USBR CFD MODEL

:

CFD MODEL AT ALDEN LABS

ANALYTICAL COMPS ABOUT 10% LOWERTHAN OTHERS

MODELS WERE CLOSE.

BUILDING STRONG


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Design Flow (135,000 cfs)

Velocity (ft/s)

Pressure (psi)

BUILDING STRONG28


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Velocity (ft/s)

Pressure (psi)

BUILDING STRONG29


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Velocity (ft/s)

Pressure (psi)

BUILDING STRONG30


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BUILDING STRONG


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Test section for atmospheric

work on laboratory floor.

BUILDING STRONG


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PIV data (large steps-slope

0.4)Step 4 velocity Step 14 velocity

BUILDING STRONG


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= .

BUILDING STRONG


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= .

BUILDING STRONG


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INTERACTION OF STEPS AND BASIN

BUILDING STRONG


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MODELING

NOT FULLY ADDRESSED - -

NEED FOR ADDED AERATION

BUILDING STRONG

design of stepped spillway

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