Evaluating comparative performance of various shaped bridge piers: experimental investigation of sediment transport and scouring

Gibson, David Eric (2010) Evaluating comparative performance of various shaped bridge piers: experimental investigation of sediment transport and scouring. [USQ Project] (Unpublished)

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Abstract

[Abstract]: The term scour in this dissertation refers to a general lowering of the of the natural stream bed level caused by erosion. Local scour is the direct result of an interferance in the flow of water caused by a structure such as a bridge pier and is characterised by the formation of scour holes around the perimeter of the bridge pier. Local scour has the potential to threaten the structural integrity of bridge pier foundations. Local scour testing under Clearwater conditions of a circular, straight aerofoil, and skirted aerofoil model bridge pier in a non uniform erodible cohesionless bedding material was investigated experimentally in a large flume. The aim of the research was to examine and evaluate the comparative performance of the scouring and sediment transport potential for the three different shaped scaled model bridge piers. Performance of the three scaled model bridge piers was assessed by measuring dimensions and volumes of the scour holes with a laser scanner and velocities with an acoustic doppler velocimeter. Scour dimensions and volumes were measured within the volumetric area of the cohesionless bedding material. Results from experimental field testing show that scour hole volumes as a percentage of the circular pier scour hole volume were 74% for the straight aerofoil pier and 60% for the skirted aerofoil pier. Further, scour hole depth measured at the upstream face for the skirted aerofoil pier was 73% of the circular pier scour hole depth. Velocity plots 800mm downstream from the circular pier demonstrate that eddies were still present within the flow for the circular pier. For the straight and skirted aerofoil piers, velocity plots demonstrate eddies were significantly reduced within the flow at the same location. Results demonstrate that symmetrical aerofoil shaped piers are an effective countermeasure in the reduction of local scour hole volume. The skirt on the aerofoil shaped pier is an effective countermeasure in the reduction of local scour depth.


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Item Type: USQ Project
Refereed: No
Item Status: Live Archive
Depositing User: epEditor USQ
Faculty / Department / School: Historic - Faculty of Engineering and Surveying - Department of Agricultural, Civil and Environmental Engineering
Date Deposited: 01 Mar 2011 05:45
Last Modified: 03 Jul 2013 00:31
Uncontrolled Keywords: bridges; bridge; piers; bridge piers; scouring; flow
Fields of Research (FOR2008): 09 Engineering > 0905 Civil Engineering > 090502 Construction Engineering
09 Engineering > 0905 Civil Engineering > 090506 Structural Engineering
URI: http://eprints.usq.edu.au/id/eprint/18490

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