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Waterway Structures in the Northern Tier - Phase 2.
| 题名： | Waterway Structures in the Northern Tier - Phase 2. |
| 作者： | johnson, p. miller, a. newlin, j. meece, k. hauser, j. |
| 关键词： | streams, sediment transport, channel flow, deposition, bridges, flood control, vanes, maintenance, pennsylvania, design procedures, mathematical models |
| 摘要： | Many streams in the northern areas of Pennsylvania convey very heavy bed loads during some storm events. Heavy bed load transport can become a problem at waterway structures if the capacity of the channel at the structure is insufficient to convey the sediment supplied to it from upstream. The result is aggradation, or deposition, of material in the channel. Aggradation causes the bridge waterway opening to be reduced. At multiple span bridges, aggradation at one or more spans can lead to the potential for increased contraction scour at the remaining spans. In addition, the reduced waterway opening can cause overtopping of the bridge deck during flooding, as well as an increase in upstream flooding due to the inability of the opening to convey the water and sediment mixture. The causes of aggradation are numerous and the solutions are generally difficult and expensive to achieve. In this project we determine whether structures, such as vanes, could be used to reduce maintenance costs at bridges by improving sediment transport through the bridge opening, thereby reducing aggradation beneath the bridge. Sediment transport characteristics and the capacity of the structures to improve sediment transport through the bridge openings were assessed through the use of both mathematical and physical models. The project resulted in the identification of methods to improve maintenance and design procedures, evaluate and rand candidate procedures, and create new maintenance and design guidance for the selected procedures. / NOTE: Final rept. / Supplementary Notes: Sponsored by Pennsylvania Dept. of Transportation, Harrisburg. Bureau of Planning and Research. / Availability Note: Product reproduced from digital image. Order this product from NTIS by: phone at 1-800-553-NTIS (U.S. customers); (703)605-6000 (other countries); fax at (703)605-6900; and email at orders@ntis.gov. NTIS is located at 5285 Port Royal Road, Springfield, VA, 22161, USA. |
| 总页数： | u0718；146p |
| 报告类型： | 科技报告 |
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