丹江口大坝二期规模运用后坝下冲刷坑变化分析

Analysis on the Change of Scour Pit Under Danjiangkou Dam after the Second Phase of Large-scale Operation

2017年汉江发生秋汛,丹江口大坝开闸泄洪达33 d,对坝下冲刷坑影响较大的主要是深孔泄洪。深孔射流的水量、挑距和抛射高度受坝上水位所控制,坝上水位越高,深孔下泄流量越大,水舌抛射越高,射流挑距也越远,而射流入水的倾角却越小。丹江口大坝加高后,正常蓄水位由157 m提高至170 m,深孔泄流对坝下游冲刷距离及强度都较加高之前增强。本文主要依据丹江口水利枢纽坝区下游冲刷坑2017年地形及相关水文观测资料,对冲刷坑进行分析。结果表明,冲刷坑随着水力条件的改变而产生新的变化。

In 2017,the Hanjiang river experienced an autumn flood.The floodwater of the Danjiangkou Dam had been released for 33 days.The major impact on the scour pit under the dam is mainly deep outlet discharge.The water yield,trajectory Length and thrown height of the deep outlet jet are controlled by the water level above the dam.The higher the water level on the dam,the greater the discharge flow under the deep outlet.The higher the water jet is,the farther the jet flow will be,and the smaller the inclination of the jet flow will be.After the heightening of the Danjiangkou Dam,the normal pool level increased from 157 m to 170 m.The deep outlet discharge enhances the scouring distance and strength downstream the dam than before.This paper mainly analyzed the scour pits based on the 2017 topography and related hydrological observation data of the scour pits downstream the Dam of the Danjiangkou Hydro-Junction.The results show that the scour pits have new changes as the hydraulic conditions change.