Stream Channel Migration Effects on Bridge Approaches and Conveyance PDF Download

Author: Ben Chie Yen
Publisher:
ISBN:
Category : Bridges
Languages : en
Pages : 170

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Book Description
The main objective of this project is to investigate channel protection techniques, especially those with low-cost and low-maintenance, for control of channel migration near bridge approaches. Such low cost techniques are more applicable to small streams than to large rivers. A literature review was conducted. Channel migration is mitigated either through protection of the bank and/or bed erosion and considerable deposition, or through instream structures to redirect the flow, or both. Useful control techniques include: instream structures such as bendway weirs, riprap and masonry revetment, bioengineering techniques such as willow posts, and geosynthetic membranes. Advantages and disadvantages of these techniques are summarized. Based on the information obtained from a survey of Illinois bridge sites and under the guidance of the Technical Review Panel, four sites were selected for further study of applicability of the protection techniques. For every site it has been identified that the meander pattern of the stream is a major factor for the scour and flow action endangering bridge safety. Therefore, the general goals of the suggested alternative actions are to stabilize and/or improve the stream meander alignment and to control and protect against local bank scour. The alternatives for a site range from positive "active" control structures to "passive" protection and sediment deposition enhancement. Generally, the more "active" alternatives are more costly but have less failure risk when compared to the more "passive" alternatives.