Enhancement of FDOT's SERF Device and a Study of Erosion Rates of Rock, Sand, and Clay Mixtures using FDOT's RETA and SERF Equipment, Summary

摘要

Scour, erosion of the river bottom around a bridges foundations, is the primary cause of bridge failure in the U.S. As many as 200,000 bridges are susceptible. Given the scale of the problem and the potential expense of remediating it, it is important to have dependable predictive methods to aid the design and repair processes. Though most bridge sites are over sand bed channels, many bridge channels contain clay or rock that is, to differing levels, resistant to scour. Treating such scour-resistant channels as sand results in significant over-conservatism and wasted resources. Thus, predictive methods for rock and clay soils are needed for proper stewardship of public resources. The best predictive methods for cohesive materials require a parameter, the sediment transport function, which relates flow conditions to bed material erosion rate in the absence of the structure. Equations exist for predicting this parameter, but they are difficult to compute and often do not correlate to the variable erosion-resistant conditions found in soils. Current standards recommend measuring sediment transport functions in a laboratory, but there has been some question as to how to do this accurately. In this project, University of Florida researchers developed critical refinements to these measurements that improve the methodology and produce more consistent and reliable results.