泥沙研究

基于2008—2023年实测资料分析了向家坝水电站下游河道的冲淤演变规律,采用数值模拟计算了大流量条件下近坝河段的极限冲刷情况。天然情况下,向家坝水电站下游河道河床相对稳定,冲淤基本平衡;施工截流期,坝下游4.0 km范围内的河段冲刷明显,深泓线平均下切5.0 m左右,而距坝超过4.0 km的河段整体变化较小;水库运用后,坝下游32.0 km的河段深泓平均下切0.33 m,其中距坝13.0～16.0 km的河段整体下切5.0 m左右,主要与采砂有关;整体来看,2012—2023年下游河道累积冲刷1 103万m³,其中人工采砂917万m³,河道水流冲刷仅186万m³;在20 000 m³/s大流量条件下,下游距坝2.1 km的断面刷深3.63 m,距坝6.0 km的断面冲刷2.21 m,大流量条件下向家坝下游河床仍有可能发生较大冲刷。

Based on observed data from 2008 to 2023, the channel evolution of erosion and deposition downstream of the Xiangjiaba Hydropower Station was systematically analyzed, and the estimate extreme scour depth near the dam during high flow events was simulated. The results show that the downstream channel remains relatively stable with erosion and deposition in general balance under natural conditions. However, the significant scouring has been observed within 4. 0 km downstream of the dam during the construction period,where the deep thalweg line undercut by an average of approximately 5. 0 m, while changes beyond 4. 0 km are minor. Since the operation of the hydropower station, an average thalweg undercut of 0. 33 m has occurred in the entire study area of 32. 0 km in length, the undercut in the reach 13. 0 to 16. 0 km downstream of the dam is about 5. 0 m, which is mainly caused by the sand mining. Between 2012 and 2023, totaled cumulative erosion is 11. 03 million m³, of which 9. 17 million m³ resulted from artificial sand mining and only 1. 86million m³ from natural erosion. Numerical simulations show that under a high flow discharge of 20 000 m³/s,the extreme scour depths can reach to 3. 63 m at 2. 1 km and 2. 21 m at 6. 0 km downstream of the dam,suggesting that significant scouring may still occur when the strong flood occurs.