Vertical 2-D Numerical Simulation On Sand Pit Evolution

The research on evolution process of sand pit is very important for evaluating the impact ofsand excavation and sand excavation planning.In this paper, solving free surface withσcoordinate transformations and surface functionmethod, discretizing the governing equations with DFM and staged transformation based onstagger grid system, proposing a method for the adjustment of riverbed height when it collapsed,the author established a new vertical 2-D mathematical model of flows and suspended sedimenttransport. The hydrodynamic part of the model was tested by simulating the motion of microwave and comparing the simulated results with theoretical values；the author used the sedimentmodel to simulate the experiment of riverbed armoring by clear water and calibrated thesediment model by comparing the simulated results with the experimental data. The results ofmodel verification show that the vertical 2-D mathematical model of flow and suspendedsediment transport built in this paper can simulate the evolution progress of sand pit fairly good.Then the author studied the evolution process of the riverbed without sand pit with thecalibrated model, and analyzed the impact of sediment diffusion coefficient and import sedimentto the evolution process of the riverbed. On the base of above analysis and by choosing differentparameters,the author simulated the evolution process of sand pit at silting and scoured reachesrespectively. The results show that sand excavation in a scoured river is more harmful.