NextScour for improving bridge scour design in the United States

摘要

The US Federal Highway Administration (FHWA) is developing the next-generation scour programme – that is,NextScour – to improve scour analysis for safe and economical bridge foundation design. NextScour recognises thatscour phenomena consist of two major components: (a) water and hydraulic forces and (b) erosion resistance of soilsand their associated geotechnical effects. Consequently, the programme consists of two focus areas: NextScour-Hydraulic and NextScour-Geotechnical. NextScour seeks to research and develop a design tool that computeshydraulic loads across the bathymetric domain. When linked to geotechnically derived subsurface erosion maps/stratigraphy and information of NextScour, the design tool produces instantaneous three-dimensional scourbathymetries around all bridge foundation elements. A bridge replacement project from the Virginia Department ofTransportation provided an excellent case study of the potential cost saving by considering NextScour proof-ofconceptresults in the design process. The J. Sterling Jones Hydraulics Research Laboratory erosion tests determinedthe erosion resistance of the clay layer at the bridge foundation, and a hydraulic force depth decay function wasdeveloped along with the soil depth. The proof-of-concept analysis showed a potential reduced pier scour estimateby 15.7 feet (ft) (4.8 m) and contraction scour estimate by 16.4 ft (5.0 m), 44 and 65% reductions from the originalscour analysis, respectively. NextScour empowers FHWA’s future scour analysis with the goal to improvesignificantly the accuracy of bridge scour estimates.