Scour control at bridge piers using macro-roughness elements

Abstract

A new approach involving macro-roughness elements is proposed as a scour countermeasure at circular bridge piers subject to debris accumulation. Experiments were carried out under clear water conditions with the approaching flow velocity set at the threshold of sediment motion. The efficiency of the method was investigated in terms of scour morphology reduction and temporal scour evolution. The results show the effectiveness of the method in reducing maximum scour depth. In some cases, the elements did not reduce the maximum scour depth but were effective in reducing the volume of the scour hole. Based on the experimental data, empirical equations were derived to estimate the temporal local scour depth in the presence of debris accumulation and macro-roughness elements

Performance Evaluation of Scour Protection around a Bridge Pier through Experimental Approach

“…Scouring around bridge piers is a crucial hydraulic engineering problem. It is broadly acknowledged that localized scouring is one of the main causes of bridge collapse apart from structural design issues, inadequate maintenance, and traffic overloading [1][2][3][4][5][6]. The local scouring of a bridge pier is mainly due to the downwards direction currents at the location of pier front.…”

“…The local scouring of a bridge pier is mainly due to the downwards direction currents at the location of pier front. The scouring mechanism is intensified, and the scouring pit is expanding and wider because of a horseshoe vortex formation at the base of the pier [5,[7][8][9][10][11]. Thus, proper understanding of scouring process and more precise scour depth estimation around pier shape is of utmost significance in Civil engineering.…”

Editorial

“…In the paper by Woods (2015), a new catchment-based method is developed to better integrate UK climate change data into design flood estimation and flood risk modelling. The other three papers focus on reporting results from physical modelling studies investigating new methods of scour control at bridge piers (Pagliara et al, 2015), the operating conditions of a new baffle-brush fish pass design (Kucukali and Hassinger, 2015), and the characteristics of air frequency distributions in self-aerated flows (Deng et al, 2015).In the first briefing paper of the issue, Deng et al (2015) present results from an experimental study on the development of selfaerated open channel flows. The process of self-aeration within high-velocity open channel flows has particular relevance to spillway and chute design where the volume of entrained air can have a significant influence on the depth of the flowing water layer generated.…”

“…In the paper by Woods (2015), a new catchment-based method is developed to better integrate UK climate change data into design flood estimation and flood risk modelling. The other three papers focus on reporting results from physical modelling studies investigating new methods of scour control at bridge piers (Pagliara et al, 2015), the operating conditions of a new baffle-brush fish pass design (Kucukali and Hassinger, 2015), and the characteristics of air frequency distributions in self-aerated flows (Deng et al, 2015).…”

“…These scour problems can be exacerbated further by the partial obstruction of two-phase, water-sediment flows around the pier by large accumulations of floating debris, which can result in localised flow accelerations. Within the paper by Pagliara et al (2015), scaled flume studies are conducted to test the efficiency of a novel scour countermeasure involving the placement of regular grid arrays of macroroughness elements downstream of a circular bridge pier with a large debris accumulation. The results show that the macroroughness elements arrays have a significant effect in reducing the maximum scour depth and/or the overall scour volume and planar surficial area.…”