Risk reduction measures of large wood accumulations at bridges
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10652_2019_9719_ReferencePDF.pdf
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22.79 MB
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38789eb4a6d25331f5418004c8de8013
Author(s)
Schalko, Isabella
Schmocker, Lukas
Weitbrecht, Volker
Boes, Robert M
Date Issued
October 19, 2019
Publisher
Springer Netherlands
Version
Author's final manuscript
Abstract
Abstract
Bridges with and without piers are prone to large wood (LW) accumulations during floods, possibly resulting in an upstream backwater rise, local scour, or destabilization of the structure. To reduce the flood hazard, measures are required that decrease the accumulation probability p of LW. This paper presents a literature review on existing measures to reduce p at bridges. In addition, a series of flume experiments was conducted to examine structural measures at bridge piers regarding their accumulation risk reduction effect. The objective was to test the efficiency of (1) LW fins and (2) bottom sills including various configurations. The resulting p was then compared to the setup without measures. The tested configurations of a LW fin did not decrease p. Bottom sills, in contrast, are a promising measure to reduce p for a defined range of boundary conditions. The installed sills lead to enhanced turbulence and increased surface waves. The best results to reduce p were obtained with two consecutive sills, leading to an average reduction of p by 30%. In contrast to retaining LW with retention structures, LW can be safely guided downstream, thereby preserving its relevant ecological role in rivers. However, the efficiency of bottom sills strongly depends on the approach flow and the sediment transport conditions.
MIT Department
Massachusetts Institute of Technology. Department of Civil and Environmental Engineering
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DOI of Published Version
https://doi.org/10.1007/s10652-019-09719-4
