Scour at bridge abutments is one of the most prevalent causes of bridge failure and result in disturbance in traffic and even loss of life. In order to control the bridge abutment scour, there are two countermeasures: first, mechanical stabilization by using protection units like riprap, gabions, cable tied blocks and etc., and the second is flow altering units like guide banks, dikes, spurs and so on. Recently use of geobags and geomats instead of traditional materials spread widely in controlling scour around hydraulic structures. Geobags are geotextile cloth bags filled with dredged materials, sand or concrete. Because of low cost, easy performance and availability, geobags and geomats are good supersedences for other countermeasures like riprap. This paper presents a Computational Fluid Dynamics (CFD) modeling of bridge abutment scour protection by using geomats. The model has been used to solve three dimensional, transient, Navier-Stokes equation. A nonlinear RNG turbulence model was used for modeling of the flow field near the abutment, where horseshoe vortices are formed and the turbulent flow is more dominant. The influence of geomats’ geometry in controlling vertical wall abutments scour has been studied. The results showed that, geomats may protect the abutment itself from scouring well, but the scour may shift to the downstream of the abutment.
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