Numerical Simulation For Spur Dike’s Water And Sediment Motion And Waterlogging Characteristics Under The Action Of Unsteady Flow

Spur dike is the most common building in mountain river channel’s regulation,due to the mountain river’s rapid flow and slope is steep, also the change of water levelis obvious, waterlogging phenomenon is serious, carry on sand movement simulationand waterlogging phenomenon in Spur dike under unsteady flow conditions forimproving the mountain river waterway project plan, design and management has themajor theoretical and practical value. This paper focuses on the two-dimensionalnumerical simulation method which under the unsteady flow and sediment movementand damaged on spur dike’s features, by comparing and analyzing simulation results,summed up the particular movement regulation of spur dike’s water and sedimentunder unsteady flow conditions and the actual contrast to the situation to ensure theeffective and rational scientific study of numerical simulation methods.This paper is based on the sediment transport mechanics, computational fluiddynamics and other disciplines theory, according to the characteristics of the damagedspur dike’s field trips and theoretical analysis, combined with the physical model testresults, with the using of water, sand simulation software functions MIKE21tosimulation of two-dimensional numerical simulations on spur dike’s hydrodynamic andmovable bed model under unsteady flow conditions to explore the flow structure ofspur dike, simulation method of sediment deposition under unsteady flow conditions,and obtained the following conclusions:1. Based on the finite volume method, Two-dimensional shallow water equationsand bed deformation equation model which divided it discretely by unstructuredtriangular mesh discrete units and it is reliable in calculating spur dike’s water andsediment movement under unsteady flow conditions, the study method can providesupport for corresponding physical model experiments and theoretical analysis.2. According to the test, compared with the traditional split calculation of MIKEsoftware, using SMS software can optimize the model grid, so that mesh’s qualitywould be better and model calculation would be more stable; And the simulationmethod which use in specific file as the interface to combine SMS software withMIKE software is feasible and effective, it would be better to simulate the terrain andcharacteristics of water flow and sediment motion of spur dike than the traditional MIKE method.3. Spur dike’s water movement under unsteady flow conditions has its speciallaws: the maximum current speed of whole flow field are mainly concentrated in thetop of the dam and downstream of the spur dike’s main areas; the flow rate in front ofdam increases from zero along the dam axis direction, it approximately lineardistribution at the range of the dam length; the current speed which near the flowdynamic axis of spur dike increase first and then decrease, the maximum appear in thedownstream of the spur dike; the recirculation zone’s generates position after the damcoincides with the maximum current speed which at the range of downstream of thespur dike.4. Because of the effect of unsteady flow, the downstream of flow field and waterlevel of spur dike presents a special relationship, the higher water level, the largerwater flow rate, and the flow rate of the recirculation zone is small but water levelrelatively low, the lowest point is in refluxing whirlpools.5. Unsteady stream erosion model of spur dike mainly include five characteristics:scour, siltation dunes, scour, dam body collapse and erosion after dam. Riverbeddeformation caused by the large peak flows are important causes of water damageoccurred on the spur dike.