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Scour Analysis of Proposed Atchison Bridge over the Missouri River

Scour Analysis of Proposed Atchison Scour Analysis of Proposed Atchison Bridge over the Missouri RiverBridge over the Missouri River

University of KansasTravis Malone, Shannon Milburn and David Parr

University of KansasUniversity of KansasTravis Malone, Shannon Milburn and David ParrTravis Malone, Shannon Milburn and David Parr

22

AcknowledgementsAcknowledgementsAcknowledgements

KDOT KDOT –– John JonesJohn Jones–– Mark HurtMark Hurt–– Kris NortonKris Norton–– Brad Brad RognlieRognlie–– Rudy Rudy

ReynoldsReynolds–– Ken Hurst Ken Hurst –– Mike OrthMike Orth

HNTBHNTB–– Jeff Evans Jeff Evans –– Bob LyonsBob Lyons

KUKU–– Jim WeaverJim Weaver

33Bridge Location and Pier of InterestBridge Location and Pier of InterestBridge Location and Pier of Interest

Proposed Bridge

Proposed Bridge

Pier No. 7Pier No. 7RR BridgeRR Bridge

Existing USHW 59

Existing USHW 59

Flow

Flow

NavigationChannel

NavigationChannel

44RR Piers and Existing Bridge Pier No. 10RR Piers and Existing Bridge Pier No. 10RR Piers and Existing Bridge Pier No. 10

44’x16’44’x16’ 60’x20’60’x20’

55

In-line Position for the 4-Lane Proposed Bridge Pier

InIn--line Position for the line Position for the 44--Lane Proposed Bridge PierLane Proposed Bridge Pier

Flow78’

212’

37.3’

15o

Proposed 4-lane

Existing US HW 59

Railroad

15’

Flow78’

212’

37.3’

15o

Proposed 4-lane

Existing US HW 59

Railroad

15’

1/75 model scale

37.5’ x 8’37.537.5’’ x 8x 8’’ 44’ x 16’4444’’ x 16x 16’’ 60’ x 20’6060’’ x 20x 20’’

66Site Issues that Create Scour ConcernSite Issues that Create Scour ConcernSite Issues that Create Scour Concern

Existing scour holeExisting scour holeExisting scour hole

Alternative Locations

for Pier No. 7

Alternative Locations

for Pier No. 7Pier No. 7Pier No. 7Pier No. 7

$$

Flow

Flow

15o skew angle1515o o skew angleskew angle

77

Effect of Skew AngleEffect of Skew AngleEffect of Skew Angle

CSU Pier Scour Eq.CSU Pier Scour Eq.

L

a

θθ

L

a

θθScour depth increases

50% for 15o Skew AngleScour depth increases

50% for 15o Skew Angle

88Existing Scour Hole (12/08/00)Existing Scour Hole (12/08/00)Existing Scour Hole (12/08/00)

RR PiersRR Piers

Pier 10Pier 10

18-ft ScourDepth

18-ft ScourDepth

99

Scour IssuesScour IssuesScour IssuesScour effect of lateral spacing of Proposed Pier No. 7 relative to Existing Pier No. 10.

Scour effect created by cofferdam placed downstream from Existing Pier No. 10 during construction phase.

Scour effect of degree of demolition (pier height remaining) of Existing Pier No. 10.

Scour effect of lateral spacing of Scour effect of lateral spacing of Proposed Pier No. 7 relative to Proposed Pier No. 7 relative to Existing Pier No. 10.Existing Pier No. 10.

Scour effect created by cofferdam Scour effect created by cofferdam placed downstream from Existing Pier placed downstream from Existing Pier No. 10 during construction phase.No. 10 during construction phase.

Scour effect of degree of demolition Scour effect of degree of demolition (pier height remaining) of Existing (pier height remaining) of Existing Pier No. 10. Pier No. 10.

1010

ObjectivesObjectivesObjectives1. Study the scour effects of the lateral spacing

between Proposed Pier No. 7 and Existing Pier No. 10 for the 500-year flood. (2-lane and 4-lane proposed piers considered.)

1.1. Study the scour effects of the lateral spacing Study the scour effects of the lateral spacing between Proposed Pier No. 7 and Existing Pier between Proposed Pier No. 7 and Existing Pier No. 10 for the 500No. 10 for the 500--year flood. (2year flood. (2--lane and 4lane and 4--lane proposed piers considered.)lane proposed piers considered.)

s(37.5’)ns Flow

s(37.5’)ns Flow

1111

Objectives (Cont.)Objectives Objectives (Cont.)(Cont.)2. Study the scour effects of the lateral spacing

between the cofferdam and Existing Pier No. 10 for the 5-year flood.

2.2. Study the scour effects of the lateral spacing Study the scour effects of the lateral spacing between the cofferdam and Existing Pier No. between the cofferdam and Existing Pier No. 10 for the 510 for the 5--year flood.year flood.

s

ns Flow

100’x50’

44’x16’s

ns Flow

100’x50’

44’x16’

1212

Objectives (Cont.)Objectives Objectives (Cont.)(Cont.)3. Develop a method for estimating pier scour

due to a partial height pier. This would occur if the Existing Pier No. 10 were partially demolished to a height of yf above the bed.

3.3. Develop a method for estimating pier scour Develop a method for estimating pier scour due to a partial height pier. This would occur due to a partial height pier. This would occur if the Existing Pier No. 10 were partially if the Existing Pier No. 10 were partially demolished to a height of demolished to a height of yyff above the bed.above the bed.

y2

yf Vf

V2y2

yf Vf

V2

1313

ProceduresProceduresProcedures

Sediment flume – observation of scour.

1.33-ft wide sediment flume (38-ft long) (D50 = 0.3mm)

Water only flumes – dye injection and observation of flow patterns.

2.5-ft rectangular flume (55-ft long)6.3-ft channel-shaped flume (24-ft long)

Sediment flumeSediment flume –– observation of scour.observation of scour.

1.331.33--ft wide sediment flume (38ft wide sediment flume (38--ft long) ft long) (D(D5050 = 0.3mm)= 0.3mm)

Water only flumesWater only flumes –– dye injection and observation dye injection and observation of flow patterns.of flow patterns.

2.52.5--ft rectangular flume (55ft rectangular flume (55--ft long)ft long)6.36.3--ft channelft channel--shaped flume (24shaped flume (24--ft long)ft long)

Objectives 1 and 2 were achieved using flow visualization and observation of scour in laboratory flumes.

Objectives 1 and 2 were achieved using flow Objectives 1 and 2 were achieved using flow visualization and observation of scour in visualization and observation of scour in laboratory flumes.laboratory flumes.

1414FlumesFlumesFlumes

2.5-ft Flume2.52.5--ft Flumeft Flume6.3-ft Flume6.36.3--ft Flumeft Flume

Sediment FlumeSediment FlumeSediment Flume

1515Froude No. SimilarityFroude No. SimilarityFroude No. Similarity

1/ 2 5/ 2

1/ 2 3/ 2

1

;

;

pmm p r

m p

r r r r r r r

r r r r r r r

VVFr Fr Frgy gy

Undistorted Model

x y L V L Q LDistorted Model

x y V y Q x y

= = = → =

= = → = =

≠ → = =

Horizontal Vertical Velocity Dischargexr yr Vr Qr

Sand Flume 1/300 1/96 0.102 3.54 E-066.3-ft Wide Flume 1/150 1/96 0.102 7.09 E-62.5-ft Wide flume 1/75 1/75 0.115 2.05 E-6( )r =( )model/( )prototype =( )m/( )p

ModelHorizontal Vertical Velocity Discharge

xr yr Vr Qr

Sand Flume 1/300 1/96 0.102 3.54 E-066.3-ft Wide Flume 1/150 1/96 0.102 7.09 E-62.5-ft Wide flume 1/75 1/75 0.115 2.05 E-6( )r =( )model/( )prototype =( )m/( )p

Model

1616

ObservationsObservationsObservationsScour studies in the sediment flume were very valuable. The effect of lateral pier spacing was evident and measurable. Objectives 1 and 2 were met using the sediment flume.

Dye studies were interesting but did not provide as much in the way of meeting Objectives 1 and 2 as did the sediment flume experiments.

Scour studies in the sediment flume Scour studies in the sediment flume were very valuable. The effect of were very valuable. The effect of lateral pier spacing was evident and lateral pier spacing was evident and measurable. Objectives 1 and 2 measurable. Objectives 1 and 2 were met using the sediment flume.were met using the sediment flume.

Dye studies were interesting but Dye studies were interesting but did not provide as much in the way did not provide as much in the way of meeting Objectives 1 and 2 as of meeting Objectives 1 and 2 as did the sediment flume did the sediment flume experiments.experiments.

1717

RESULTSRESULTSRESULTS

1818

Sediment FlumeSediment FlumeSediment Flume

1919Model Piers for Sediment Flume

(1/300 hor. scale; 1/96 vert. scale)Model Piers for Sediment Flume

(1/300 hor. scale; 1/96 vert. scale)

4-lane4-lane 2-lane2-lane CofferdamCofferdamExistingExisting

2020

Sediment FlumeSediment FlumeSediment FlumeOnly used existing and proposed piers. No RR pier modeled. A cofferdam was also tested.

Piers were set up to slide along bridge centerlines. (Skewed 15o to flume cl)

Observed effects relative to the lateral position of piers.

Only used existing and proposed piers. Only used existing and proposed piers. No RR pier modeled. A cofferdam was No RR pier modeled. A cofferdam was also tested.also tested.

Piers were set up to slide along bridge Piers were set up to slide along bridge centerlines. (Skewed 15centerlines. (Skewed 15oo to flume to flume clcl))

Observed effects relative to the lateral Observed effects relative to the lateral position of piers.position of piers.

2121

Sediment Flume

4-Lane Overhead View

(500-year Flood)

Sediment FlumeSediment Flume

44--Lane Overhead ViewLane Overhead View

(500(500--year Flood)year Flood)

2222Proposed Pier OnlyProposed Pier OnlyProposed Pier Only

2323Existing Pier No. 10 OnlyExisting Pier No. 10 OnlyExisting Pier No. 10 Only

24240 Lateral Spacings, 4-Lane Proposed 0 Lateral 0 Lateral SpacingsSpacings, 4, 4--Lane Proposed Lane Proposed

25251 Lateral Spacing 4-Lane Proposed 1 Lateral Spacing 41 Lateral Spacing 4--Lane Proposed Lane Proposed (1 spacing = 37.5 ‘ in prototype)(1 spacing = 37.5 (1 spacing = 37.5 ‘‘ in prototype)in prototype)

26262 Lateral Spacings, 4-Lane Proposed2 Lateral 2 Lateral SpacingsSpacings, 4, 4--Lane ProposedLane Proposed

3030

Sediment Flume

4-Lane Side View

(500-year Flood)

Sediment FlumeSediment Flume

44--Lane Side ViewLane Side View



Note the2” markerNote the2” marker


2” marker2” marker

3333

6.3-ft Flume(500-year Flood)

6.36.3--ft Flumeft Flume(500(500--year Flood)year Flood)

3434Dye Between PiersDye Between PiersDye Between Piers

Largest Eddies,No Lateral Spacing

Largest Eddies,No Lateral Spacing

Smallest Eddies, Widest Lateral Spacing

Smallest Eddies, Widest Lateral Spacing

3535

2.5-ft Flume(500-year Flood)

2.52.5--ft Flumeft Flume(500(500--year Flood)year Flood)

3636EddiesEddiesEddies

Largest EddiesNo Lateral Spacing

Largest EddiesNo Lateral Spacing

Smaller EddiesWider Lateral Spacing

Smaller EddiesWider Lateral Spacing

3737

50’ x 100’Cofferdam

(5-year Flood)

5050’’ x 100x 100’’CofferdamCofferdam


3838Cofferdam and Existing Pier No. 10Cofferdam and Existing Pier No. 10Cofferdam and Existing Pier No. 105 Lateral Spacings (187.5’)5 Lateral 5 Lateral SpacingsSpacings (187.5(187.5’’))Pier and Cofferdam AlignedPier and Cofferdam AlignedPier and Cofferdam Aligned

Existing Pier OnlyExisting Pier OnlyExisting Pier Only Cofferdam OnlyCofferdam OnlyCofferdam Only

(a)(a) (b)(b)

(c)(c) (d)(d)

Glass BottomGlass BottomGlass Bottom

3939

Pier Scour for

Partial-Height

Piers

Pier Scour for Pier Scour for

PartialPartial--HeightHeight

PiersPiers

4040Partial Pier Equations from HEC-18Partial Pier Equations from HECPartial Pier Equations from HEC--1818

⎟⎟⎠

⎞⎜⎜⎝

⎛

⎟⎟⎠

⎞⎜⎜⎝

⎛

=

s

s

f

f

kyky

VV

22 93.10ln

93.10ln

`

(6.14)

and

43.065.0

43210.2 ⎟⎟

⎠

⎞

⎜⎜

⎝

⎛

⎟⎟⎠

⎞⎜⎜⎝

⎛=

f

f

f

pcW

f

spc

gy

Vya

KKKKKyy

(6.15)

EqEq. 6.14. 6.14

EqEq. 6.15. 6.15

yyffVVff

yy22

VV22

spcwhere y scour depth=

4141

Pier Scour Depth for Partial Pier

10

20

30

40

0 10 20 30 40 50

Pier Height (ft)

Pie

r S

co

ur

y2 46.3 ftv2 13.3 ft/sec

apc 12 ftK1 1K2 1.5K3 1.1K4 1Kw 1g 32.2 ft/sec2

(mm) (ft)ks = D84 1.5 0.00492

Parameters

yf (ft) yspc (ft)

0.1 12.70.5 17.61 20.15 27.110 30.720 34.730 37.340 39.2

46.3 40.2!!!

Pier Scour Depth for Partial PierPier Scour Depth for Partial PierPier Scour Depth for Partial Pier

4242Pier Scour Depth for Partial PierPier Scour Depth for Partial PierPier Scour Depth for Partial Pier

1' 20.1'

46.3' 40.2 'f spc

f spc

y y

y y

= → =

= → =

yyffVVff

yy22

VV22

4343

Summary and ConclusionsSummary and ConclusionsSummary and ConclusionsPrototype lateral spacings of Proposed Pier No.

7 for negligible scour interaction at the 500-year flow are

4 spacings (150’) for 2-lane proposed pier5 spacings (187.5’) for 4-lane proposed pier

The worse scour conditions for the proposed 4-lane pier were observed for spacings of 0 and 1. Spacings of 2 or greater significantly reduced the observed pier scour.

A lateral prototype spacing of 187.5’ for the cofferdam relative to Existing Pier No. 10 still showed pier scour interaction for the 5-year flow.

Prototype lateral Prototype lateral spacingsspacings of Proposed Pier No. of Proposed Pier No. 7 for negligible scour interaction at the 5007 for negligible scour interaction at the 500--year year flow are flow are

4 4 spacingsspacings (150(150’’) for 2) for 2--lane proposed pierlane proposed pier5 5 spacingsspacings (187.5(187.5’’) for 4) for 4--lane proposed pier lane proposed pier

The worse scour conditions for the proposed 4The worse scour conditions for the proposed 4--lane pier lane pier were observed for were observed for spacingsspacings of 0 and 1. of 0 and 1. SpacingsSpacings of 2 or of 2 or greater significantly reduced the observed pier scour.greater significantly reduced the observed pier scour.

A lateral prototype spacing of 187.5A lateral prototype spacing of 187.5’’ for the for the cofferdam relative to Existing Pier No. 10 still cofferdam relative to Existing Pier No. 10 still showed pier scour interaction for the 5showed pier scour interaction for the 5--year flow.year flow.

4444

Summary and Conclusions (Cont.)Summary and Conclusions (Cont.)Summary and Conclusions (Cont.)The partial demolition of existing Pier No. 10

will not eliminate detrimental pier scour. In fact, shortening the existing pier from 46.3 feet to 1 foot would only halve the pier scour depth of the existing pier.

The existence of the scour hole between the railroad pier and Existing Pier No. 10 represents a clear warning that this region is highly susceptible to scour. This existing scour hole is probably due to the large size of the railroad pier (20’x60’) and the 15 degree skew angle of the pier relative to the flow.

The partial demolition of existing Pier No. 10 The partial demolition of existing Pier No. 10 will not eliminate detrimental pier scour. In fact, will not eliminate detrimental pier scour. In fact, shortening the existing pier from 46.3 feet to 1 shortening the existing pier from 46.3 feet to 1 foot would only halve the pier scour depth of the foot would only halve the pier scour depth of the existing pier.existing pier.

The existence of the scour hole between the The existence of the scour hole between the railroad pier and Existing Pier No. 10 represents railroad pier and Existing Pier No. 10 represents a clear warning that this region is highly a clear warning that this region is highly susceptible to scour. This existing scour hole is susceptible to scour. This existing scour hole is probably due to the large size of the railroad pier probably due to the large size of the railroad pier (20(20’’x60x60’’) and the 15 degree skew angle of the ) and the 15 degree skew angle of the pier relative to the flow.pier relative to the flow.

4545Final DesignFinal DesignFinal Design

72’72’

SpacingSpacing

4646

Demolish Existing Pier No. 10 to an elevation of 825’. This is 7’ below the bottom of the December 2000 scour hole.

Offset Proposed Pier No. 7 about 72’east of the original centerline of Existing Pier No. 10. This gets it “out of the way” of the scour hole created by the 20’x40’ railroad pier. The railroad pier will not be demolished.

Demolish Existing Pier No. 10 to an Demolish Existing Pier No. 10 to an elevation of 825elevation of 825’’. This is 7. This is 7’’ below the below the bottom of the December 2000 scour bottom of the December 2000 scour hole.hole.

Offset Proposed Pier No. 7 about 72Offset Proposed Pier No. 7 about 72’’east of the original centerline of east of the original centerline of Existing Pier No. 10. This gets it Existing Pier No. 10. This gets it ““out out of the wayof the way”” of the scour hole created of the scour hole created by the 20by the 20’’x40x40’’ railroad pier. The railroad pier. The railroad pier will not be demolished.railroad pier will not be demolished.

Final DesignFinal DesignFinal Design

4747

Questions?Questions?Questions?

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