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Design & Construction Considerations When Lining CMP Pipe-Arches - - PowerPoint PPT Presentation
Design & Construction Considerations When Lining CMP Pipe-Arches - - PowerPoint PPT Presentation
Design & Construction Considerations When Lining CMP Pipe-Arches Hugh B. Mickel, P.E. www.ContechES.com Design Methods for Lining and Sliplining Round Pipes are Usually Straightforward www.ContechES.com Construction Methods for Lining and
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Construction Methods for Lining and Sliplining Round Pipes are Usually Straightforward
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What About Pipe-Arches?
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- Design
Challenges
- Construction
Challenges
- Pipe-Arch
Case Studies
Today’s Focus Areas:
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Fit/Geometry is the 1st Major Hurdle
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Pipe-Arch Dimensions: it’s much more than just span & rise
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…Pipe-Arch History…
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From 1958 Handbook:
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- Early dimensions and tolerances varied by manufacturer.
- AASHTO M-36 and present day equipment provides
greater consistencies among manufacturers.
For More Pipe-Arch History:
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Structural Plate Pipe-Arches are in 2 Size Groupings:
- 18” Corner Radius
(shown)
- 31” Corner Radius
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What size is this structural plate pipe-arch? Count the spaces around the perimeter
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The best method for determining available space: 3D Laser Scanning
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Structural Design of Pipe-Arches is Different Compared to Round Pipe
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Soil Arching
How do you know it’s present? Where is it occurring? What can make it shift? What can negate it?
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How do you know it’s present? Where is it occurring? What can make it shift? What can negate it?
Soil Arching
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When Can a Reduced Load Be Used?
- For Rigid Pipes
- Possibly when installation records show an induced, zero projecting
- r negative projecting trench installation
- For Flexible Pipes
- Only if original soil arch is in place (recent movements negate it)
- Installation records are detailed, including deflection at the time of
acceptance
- Current and full soils investigation shows backfill and prism properties
are favorable, and there are no inconsistent areas indicating future consolidation or movements might occur
- Groundwater migration isn’t possible
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(See this paper for more information)
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- Designing Outside the Limits of AASHTO & ASTM Standards is Risky
- Examine the strength of freezing water left behind in the corrugations.
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2017 ODOT Project in Brown County
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2017 ODOT Project in Brown County
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2017 ODOT Project in Brown County
Type equation here.
Color Key: Built / Attempted / Existing
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126 pi MPPA 135pi didn’t fit
Layover of Original & Attempted, Drawn to Design Shapes :
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123 pi into 135 pi
Resubmitted a 123 pi MPPA with an improved hydraulic inlet
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New Structure with Improved Inlet and Paved Invert
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Lessons Learned
- 1. Get a 3D Laser Profile if possible, or
- 2. Provide detailed field measurements in plans
- 3. Assess possibility of movements between Scoping
and Construction
- 4. Engage us early (we have lots of knowledge)
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2017 ODOT Project in Highland County
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Tunnel Liner Plate with Paved Invert
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Under I-91 in Connecticut
- ADT: 57,000 vehicles per day
- Abrasion Level 3 site
- 22’ of fill
- Active movement
1964 MPPA – 8’-10” Span x 6’-1” Rise
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Corrosion and Invert Wall Buckling
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3D Laser Survey
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Laser scan sections
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Controlled Invert Removal Limits
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Bracing the Host Structure
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Aluminum Tunnel Liner Plate
- builds safe working environment as you go
- allows for partial & full tunneling with assembly done from the inside
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Construction
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Don’t Forget the Hydraulics
- Inlet Control vs. Outlet
Control - the governing mode is the one that produces the highest Headwater Depth (inlet end)
- HY8 v 7.50 software by
FHWA
It’s a free download at: http://www.fhwa.dot.gov/engineering /hydraulics/software/hy8/
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