Author(s): Diego Panici; Gustavo De Almeida

Linked Author(s): Diego Panici

Keywords: Large wood; Debris; Flood; Scour; Experimental hydraulics

Abstract: The accumulation of large woody debris at bridge piers can cause serious damage to bridge structures by increasing scour depth and exerting structural loads, as well as increasing the flood risk in the upstream areas. These effects are heavily dependent on the size that debris jams can form at a single pier. Recent research works unveiled relationships between flow characteristics and large wood jam size. Despite many variables have been tested in the literature, the key-parameter of pier shape has been given comparatively less attention. In this work, we experimentally tested the effect that several pier shapes can have on the formation of large woody debris accumulations. We investigated the formation of large wood jams with five different pier shapes - namely square, triangle, ogive, trapezium and half-circle. Results revealed that the mechanics by which large wood jams formed (i.e. a three-phase scheme) for circular piers was systematically observed for all pier shapes, including the final rotation about the pier that leads to the jam failure. The maximum size of the formed large wood accumulations was compared to those of circular shape. Overall, differences were negligible in most cases, except for the square pier, in which the observed size was approximately 15% larger than other shapes. These differences can be potentially explained by the flat face of the pier that is able to entrap large wood elements more easily than other shapes.

DOI: https://doi.org/10.3850/IAHR-39WC252171192022243

Year: 2022