金沙江溪洛渡水电站大坝深孔过流振动测试分析

Vibration test and analysis of dam deep hole overcurrent at Xiluodu Hydropower Station on Jinsha River

为分析溪洛渡水电站大坝深孔过流引起的振动问题,本文采用中国水利水电科学研究院自主研发的振动测试系统,对右岸制冰楼与拌合楼、大坝廊道和深孔启闭机平台及水垫塘廊道等部位开展了现场测试分析,结果表明:(1)制冰楼、拌合楼等柔性结构,以横河向振动响应为主,其振幅不影响正常运行安全;(2)拱坝深孔过流时引起大坝527岸坡坝段廊道的振动响应较低,其频带较宽且卓越频率不显著;(3)启闭机平台的振动响应相对较大,其振动响应第1阶卓越频率为1.83 Hz;通过启闭机平台与水垫塘振动响应的传递函数分析可知,该频率为大坝第1阶自振频率;(4)水垫塘底板和二道坝等泄洪消能结构,以竖向振动响应为主;水垫塘振动响应频带较宽且主频不突出;首次发现了二道坝廊道的振动响应主频随时间变化并存在间歇性低频振动,建议开展溪洛渡二道坝结构间歇性低频振动长期安全监测分析,并加强其他高拱坝水垫塘与二道坝泄洪时的低频振动安全设计。

In order to analyze the vibration problem caused by deep hole overcurrent in the dam of Xiluo⁃du Hydropower Station,field test analysis has been carried out on the right bank ice making tower and mixing tower,dam gallery,deep hole hoist platform and cushion basin gallery by the use of the vibration test system independently developed by China Institute of Water Resources and Hydropower Research in the paper.The results indicate that:(1)For flexible structures such as ice-making buildings,mixing build⁃ings,etc.,the horizontal response comes into prominence,and its amplitude does not affect normal opera⁃tion safety of the structures;(2)When there is the deep hole overcurrent in the arch dam,the vibration response of the gallery on the 527 bank slope of the arch dam is lower,the frequency band is wider and the predominant frequency is not significant;(3)The vibration response of the gate hoist platform is rela⁃tively large,and the first order excellent frequency of the vibration response is 1.83Hz;the transfer func⁃tion analysis of the vibration response of the hoist platform and the cushion basin shows that this frequency is the first-order natural frequency of the dam;(4)For flood discharge and energy dissipation structures such as cushion basin floor and secondary dam,the vertical vibration response is dominant.The vibration response frequency band of the cushion basin is wide and the main frequency is not prominent.It is found for the first time that the main frequency of vibration response of the gallery of the second dam changes with time and there is intermittent low-frequency vibration.It is suggested to carry out long-term safety monitoring and analysis of intermittent low-frequency vibration of the structure of the second dam in Xiluo⁃du,and strengthen the safety design of low-frequency vibration during flood discharge of plunge pool and the second dam of other high arch dams.