Development and Evaluation of Live-Bed Pier- and Contraction-Scour Envelope Curves in the Coastal Plain and Piedmont Provinces of South Carolina

摘要

The U.S. Geological Survey, in cooperation with the South Carolina Department of Transportation, used ground-penetrating radar to collect measurements of live-bed pier scour and contraction scour at 78 bridges in the Piedmont and Coastal Plain Physiographic Provinces of South Carolina. The 151 measurements of live-bed pier-scour depth ranged from 1.7 to 16.9 feet, and the 89 measurements of live-bed contraction-scour depth ranged from 0 to 17.1 feet. Using hydraulic data estimated with a one-dimensional flow model, predicted live-bed scour depths were computed with scour equations from the Hydraulic Engineering Circular 18 and compared with measured scour. This comparison indicated that predicted pier-scour depths generally exceeded the measured pier-scour depths, and at times predicted pier-scour depths were excessive (over predictions were as large as 23.1 feet). For live-bed contraction-scour depths, predicted scour was sometimes excessive (over predictions were as large as 14.3 feet), but often observed contraction scour was under predicted.