Study On The Optimizing Regulation Of Sediment Reduction With Unconventional Flood In Jinping-?

Severe reservoir sediment deposition will affect its normal operation,to explore efficient dredging method is an important issue in reservoir sediment research in recent years.In view of the problem of sediment deposition in reservoirs,this paper used artificial regulation to flush sand,and designed an unconventional flood flushing method,which could save the amount of flushing water and could serve as a reference to achieve economic optimum.Taking Jinping-?Hydropower Station as an example,this paper systematically studied the law of the dredging effects of different types of unconventional floods through physical model experiment and numerical simulation,and the main contents and achievements are as follows:(1)A set of manually controlled unconventional flood-flushing simulation system was constructed,which could form asymmetrical serrated periodic waves.Simultaneous real-time measurement of water depth,velocity and sediment transport rate were made for unconventional flood-flushing,and laid the foundation for the experimental study of unconventional flood-runoff regulation.(2)Unconventional flood-runoff simulation tests were carried out and it was proved that average sediment transport rate in unconventional flood tests is greater than that in the constant flood-runoff tests.The results showed that for symmetrical unconventional floods,under the condition of equal average flow rate,the sediment transport capacity increased with the increase of flow amplitude.For asymmetric unconventional floods,under the same condition of regular flood,average flow and peak flow,the capacity of sediment transport increased with the decrease of the ratio of base flow duration to peak flow duration.The numerical simulation of unconventional flood-runoff tests by Flow-3D was carried out,which provided a theoretical basis for the later actual calculation of sediment transport by numerical model.(3)Based on Flow-3D,a three-dimensional numerical model of hydro-dynamic sediment in the 7km long river of Jinping-?reservoir area was established.The model was verified by using the measured data of the Jinping-?reservoirs.The results showed that the effect of small flow rate was small and the duration was too long in the process of sediment flushing,resulting in the waste of flushing water.It is necessary to change the inflow mode to make the flushing effect better.(4)By means of three-dimensional numerical method,a reasonable unconventional flood-flushing mode was designed and the unconventional flood was optimized for sediment transport in Jinping-?reservoir area.The effect of flow rate on sediment transport was studied,and the optimal flow rate was obtained.Under the condition that the flow of Jinping-?peak flow could be increased,the sediment-carrying effect increased obviously with the increase of flow rate.The peak flow increased from 5000m~3/s to 6500 m~3/s,and the total sediment transport increased from 301,600 m~3 formed by the actual scouring sediment experiment to 484,000 m~3.Under the condition of unchanged peak flow discharge,the sediment-carrying effect was also optimized through unconventional floods on a time scale.The optimal conditions for transporting sediment totaled 465,000 m~3.