ABSTRACT
Bruce W. Melville The University of Auckland, Auckland, New Zealand
ABSTRACT: Prediction of likely scour depths at bridge foundations is an important aspect of the design of bridges. While detailed guidance is available for most aspects of the scour design of bridges, scant information is available for pressure-flow scour, which is a form of vertical contraction scour that occurs when the water surface elevation upstream from the bridge rises above the bridge low chord. The results from a recent experimental investigation of pressure-flow scour are presented. Whereas most previous data apply only to clear-water scour, the new data are for live-bed scour conditions. A preliminary design relationship for estimating pressure-scour depth is presented. The relationship is applicable to a wide range of bridge deck elevations and flow intensities, but is limited to non-cohesive (alluvial) bed materials.
