The Effect of the Shape of Bridge Pier at Scour Using Software SSIIM

Studies on hydraulic structures, especially around bridge piers, show that one of the main causes of bridge destruction is local turbulence. In order to have an economical and reliable design, the maximum scouring depth around the foundations must be achieved. Estimation of the maximum scour depth is necessary in order to determine the required depth for the bridge piers, because otherwise it may lead to the destruction of the bridge. In this research, SSIIM software has been used, which considers flow and sediment equations in three dimensions. In this software, the flow field is obtained from the Navier-Stokes equations and the εK-turbulence model, and then, using the non-permanent solution of the sediment field and the continuity equation, the floor level changes around the bridge pier are calculated. The results of this study show that the numerical model used, which is one of the three-dimensional models available to engineers, predicts acceptable values ​​in flow simulation, calculation of free surface and calculation of bed topographic changes in the river. In some places the speed calculation error increases, but the model is able to model the distribution of velocity and rotational currents well. From the presented models, it was proved that under the same conditions, the scour around the square and cylindrical base is more than the rectangular base.