Estimation of Long Term Bridge Pier Scour in Cohesive Soils at Maryland Bridges using EFA/SRICOS

Abstract

Estimation of scour in cohesive soils is based on equations developed for non-cohesive soils that produce conservative scour estimates when applied to cohesive soils. This thesis evaluates the development of bridge pier scour via SRICOS, Scour in Cohesive Soils, a method to determine bridge pier scour depth in cohesive soils using results of the Erosion Function Apparatus (EFA) erosion tests and a hydrograph. Soil samples were collected from five Maryland sites; the EFA was used to measure their erosion rates and the SRICOS software predicted scour depths over a user-determined timespan. Predicted scour depths were compared to HEC-18 predicted pier scour depths. In all instances, the EFA/SRICOS method predicted less scour than the HEC-18 method, the current design standard. EFA/SRICOS represents an emerging re-thinking of erosion characterization to predict scour depths of cohesive soils at piers.