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原文传递 Correlation of Rock Quality Designation and Rock Scour Around Bridge Piers and Abutments Founded on Rock; Research rept

题名：	Correlation of Rock Quality Designation and Rock Scour Around Bridge Piers and Abutments Founded on Rock; Research rept
作者：	Hopkins, T. C.; Beckham, T. L.
关键词：	Bridge abutements; Scour; Rocks; Bridges; Bridge piers; Alluvium; Erosion; Inspection; Kentucky; Guidelines
摘要：	Local scour around the base of a bridge pier or abutment occurs as the result of flow acceleration around the obstruction, formation of a vertical pressure gradient along the upstream end, and generation of vortices at the base of the structure. The flow patterns around piers and abutments are complex in detail, and the complexity increases as a scour hole forms in the bed around the structures. The potential for local scour at a bridge pier or abutment needs to be estimated so that foundations can be designed to resist failure during large floods. While procedures have been suggested for estimating local scour depths at bridge piers and abutments located on, or in unconsolidated alluvial material, only interim FHWA (Federal Highway Administration) guidelines (July 1991) in the form of memorandum are available for evaluating the scour potential at footings placed on rock. The empirical guides relate quantifiable geotechnical indices to a qualitative measure of the ability of the foundation rock to resist erosion. To test the validity of some of the more significant FHWA guidelines for assessing the rock scour, on-site inspections of some 400 bridges with footings located on exposed rock were performed. A large number of bridge abutments and piers in Kentucky were found to have been placed on rock foundations that are visible during low flow. These inspections show that scour at bridge piers and abutments placed on rock does occur.
总页数：	88p
报告类型：	科技报告