Application of HEC-RAS 2D model to simulate scour depth around bridge piers- A case study on Hanwella Bridge, Sri Lanka

Abstract

Lowering of the level of river bed due to water erosion is denoted by the term Scouring. Scouring can transpire around abutments and piers of a bridge. Pier scouring possesses a high threat to the stability of the bridge structures. The formation of vortices in the vicinity of bridges due to obstruction caused to the river flow is the core rationale behind this pursuit. Estimation of scour depth, which is the depth of the hole formed around a bridge pier due to scouring at a bridge site is indispensable in terms of the safety and economy of a bridge. Although various researchers around the world have developed numerical formulae and physical models for the simulation of scour around bridge piers, in the context of Sri Lanka, not many studies have focused on this area yet. In this study, HEC-RAS two-dimensional model is used for the determination of scour depth around the bridge piers of the Hanwella bridge built across the Kelani River of Sri Lanka. The change in bed elevation around the bridge pier provides the depth of the scour hole formed due to a considered flood event. As per the results, the hydraulic model coupled with the sediment transport model has produced a reliable estimation of the river bed level change and scour depth around the bridge piers. Further validation of the model results can be accomplished based on a series of laboratory-scale experiments.