1 1 Scour Analysis of Proposed Atchison Bridge over the Missouri River Scour Analysis of Proposed Atchison Scour Analysis of Proposed Atchison Bridge over the Missouri River Bridge over the Missouri River University of Kansas Travis Malone, Shannon Milburn and David Parr University of Kansas University of Kansas Travis Malone, Shannon Milburn and David Parr Travis Malone, Shannon Milburn and David Parr
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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
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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
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.
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.
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.
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RESULTSRESULTSRESULTS
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Sediment FlumeSediment FlumeSediment Flume
1919Model Piers for Sediment Flume
(1/300 hor. scale; 1/96 vert. scale)Model Piers for Sediment Flume
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
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.