Development of a computer simulation for scouring around bridge piers

Nankervis, Gary A. (2016) Development of a computer simulation for scouring around bridge piers. [USQ Project]


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Bridges are important and valuable items of infrastructure in modern society. They are designed to be functional and cost effective, but they must also be safe. A great many bridges cross bodies of flowing water and have supporting piers founded within the water; therefore the foundations are subject to erosion by scouring and this could lead to potential bridge failures.

The aim of this research project is to develop a computer simulation of bridge pier scouring, to accurately predict the extent of potential scouring. Accurate predictions of scouring could lead to more efficient bridge designs while still maintaining the required level of safety. The project also proposes a new pier design with potential for improved scouring performance.

There has previously been much research conducted on various aspects of bridge pier scouring. This includes explaining the scouring mechanism, physical experiments on pier geometries and developing prediction formulas. Most of this work has been done using scale models in a hydraulic flume tank and therefore has some limitations in transference to real scale situations.

In recent years computer simulations have been developed for bridge pier scouring. They have an advantage of being able to model a situation at real scale, and can easily be altered as required. Early simulations were mainly single-phase (one fluid; water) models which require empirical sediment transport equations to predict sand movement. Multiphase (more than one fluid) simulation models are a more recent development; they model sediment transport as a granular flow.

In this project Computational Fluid Dynamics (CFD) was used to develop the simulation model in ANSYS Fluent, which is a commercial software package. The model is a three-dimensional multiphase model with sand and water phases. It was based on a cylindrical control pier in a previous experiment so that known results could be used to validate the model. A new streamlined slotted pier geometry was proposed for performance testing with the model after validation.

At present, development of the model does not achieve the anticipated objective of simulating local scouring around a bridge pier. The simulation of sand, as a riverbed sediment, is not realistic. Therefore the model has not been validated and is not reliable. The sand appears to behave much more like a liquid rather than a semisolid granular flow.

The new pier design when tested in a two-dimensional (horizontal plane) model shows potential for reduced scouring. This is because of lower water velocity along its outer edges, compared to the cylindrical control pier. However it has not been possible to test the new pier in a three-dimensional scouring model.

Future successful development with this simulation model is dependent on further research and experimentation to achieve realistic sand movement. Additional models would be required specifically to better understand modelling of sand flow and the most appropriate parameter choices to achieve it.

Results from this project may offer some useful insights to other researchers, or ideas for future research projects.

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Item Type: USQ Project
Item Status: Live Archive
Additional Information: Bachelor of Engineering (Honours) Major Civil Engineering project.
Faculty/School / Institute/Centre: Historic - Faculty of Health, Engineering and Sciences - School of Civil Engineering and Surveying (1 Jul 2013 - 31 Dec 2021)
Supervisors: Wandel, Andrew
Date Deposited: 31 Jul 2017 03:07
Last Modified: 03 Aug 2017 02:45
Uncontrolled Keywords: erosion by scouring; Computational Fluid Dynamics (CFD); computer simulation; bridge pier
Fields of Research (2008): 09 Engineering > 0905 Civil Engineering > 090506 Structural Engineering
Fields of Research (2020): 40 ENGINEERING > 4005 Civil engineering > 400510 Structural engineering

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