西藏纳金电站游荡型河床泥沙病害研究

拉萨河纳金电站具有宽约２ｋｍ的游荡型河床，因库区泥沙淤积严重，电站发电、水库防洪安全日益受到威胁。通过流场分析及模型试验研究，优选出冲沙闸设置的最佳方案，冲水效果十分明显。将经过整治后的流场与过去的流场进行比较，发现过去造成泥沙淤积的大回流得以消除，从而取得稳定河势和冲淤平衡进而提高库区的防洪能力，为电站长期安全可靠运行提供保障。

Study on Sediment Deposition in Wandering Riverbed of Diversion Reach of Najin Hydroelectric Power Station in Tibet

There exists about 2 km wide, wandering riverbed in the diversion reach of Najin hydroelectric power station on Lasha river. Because of severe sediment accumulation in the reservior of the station, the electric power generation and the safety of flood control were in threaten. In order to mitigate the sediment deposition, measures must be taken. In the present paper, a silt releasing sluice is considered. By means of velocity field analysis and model test, an optimal scheme for the setting of silt-releasing sluice is determined. As a result, the sluice is very effective. Compared with the original flow field, the circumfluence that caused most of sediment deposition in the reservoir is eliminated in the regularized flow field. Then, the river regime becomes stable and the equilibrium between deposition and scouring is obtained. Consequently, the flood control capacity of the reservoir is enhanced and the plant can be safety in the long term operation.