Validating numerical model for bridge pier scour estimation through physical modelling – case study of Kelanisiri bridge

Abstract

Bridge scour is the erosion of sediment around bridge piers by flowing water, causing a significant risk to bridge stability and safety. This research explores the scouring phenomenon around a bridge pier, aiming to understand its mechanisms, develop predictive models, and propose mitigation measures in aid of a case study on Kelanisiri bridge, Sri Lanka. Physical model experiments simulate scouring depth using scaling methods, while numerical simulations enhance understanding of scour dynamics and validate the model's accuracy, ensuring similarity between model and prototype. In this study, a laboratory scale physical model, which could reproduce the scouring effect around the Kelanisiri bridge piers was developed using a laboratory flume aiming to validate the results obtained using HEC-RAS numerical model. PVC pipe and Acrylic tube models were used to measure scour depth. The results obtained from the developed physical model simulation comply well with the HEC-RAS numerical model results with acceptable R - squared and Root Mean Squared Error (RMSE) values. Accordingly, the numerical model for the estimation of scour depth can be validated through the developed laboratory scale physical model and can be considered a reliable approach for the estimation of scour depth.