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从识别结果看,在地震对应的上游 568m ,下游 378 m 水位情况下,溪洛渡拱坝的基频为 1.19
               Hz,对应的一阶振型为反对称振型,二阶频率 1.50 Hz,对应二阶振型为正对称振型; 第三阶频率
               1.67 Hz,对应振型为反对称振型,更高阶的 2.33 Hz 和 2.60 Hz 模态对应的高阶振型有明显拐点变
               化。所识别的五个模态的阻尼比为 2.6~5.4%。
                   总体上,本次强震记录的坝体地震响应较小,最大峰值加速度 8.62 gal,获得有效记录的测点并
               不完整。因此,对大坝模态参数的识别结果的精准度尚需坝体响应强度更高的记录分析成果的进一
               步对比验证,特别是模态参数中的阻尼比,对数值计算的影响十分显著,而测量结果中其对坝体的
               响应强度亦十分敏感。本次地震过程坝体材料处于线弹性范围。


               参   考   文   献:



                [ 1 ] 日 本 大 坝 协 会 . Static and Dynamic Behavior of Kurobe Dam-Record of Measurements and Observations on a
                       High Arch dam(1960-2007)[M]. 2011
                [ 2 ] 日 本 大 坝 协 会 . Report of JCOLD committee on Acceleration Records on Dams and Foundations[J]. Journal of
                       JCOLD,No.231,2015 .
                [ 3 ] PROULX J,DARBRE G R,KAMILERIS N. Analytical and experimental investigation of damping in arch dams
                       based on recorded earthquakes[C]/Proceedings of the 13th WCEE . Canada,2004 .
                                                /
                [ 4 ] 寇 立 夯 ,金 峰 ,杨 剑 ,等 . 基 于 强 震 记 录 的 二 滩 拱 坝 模 态 参 数 识 别[J]. 水 力 发 电 学 报 ,2009,28(5):
                       51-56 .
                [ 5 ]   郭明珠,杨毕康,邢国良,等 . 二滩拱坝强震台阵记录的四川普格加速度记录[J]. 地震工程与工程振动,
                       2002,22(6):12-17 .
                [ 6 ] 熊 堃 ,何 蕴 龙 ,肖 伟 ,等 . 基 于 强 震 监 测 记 录 的 冶 勒 大 坝 动 力 反 应 特 性 初 步 分 析[J]. 地 震 工 程 学 报 ,
                       2017,39(3):434-442 .
                [ 7 ] IBRAHIM S R,MIKULCIK E G . A method for the direct identification of vibration parameters from the free re⁃
                       sponses[J]. Shock and Vibration Bulletin,1977,47(4):183-198 .
                [ 8 ] IBRAHIM S R . Random Decrement Technique for Modal Identification of Structures[J]. Journal of Spacecraft
                       and Rockets,1977,14(11):696 .

                                 Modal identification of an arch dam with seismic records



                                                             1
                                                                            2
                                               1
                                   WANG Haibo ,XU Lianghua ,LIAO JianXin ,LI Deyu     1
                               (1. China Institute of Water Resource and Hydropower Research,Beijing  100048,China;
                                  2. China Three Gorges Projects Development Co.,Ltd.,Chengdu  610000, China)
                                        nd
                   Abstract:Xiluodu is the 2  largest hydropower station of China,its arch dam is equipped with 27 strong
                   seismometers for seismic monitoring. Several felt earthquakes happened near the dam site region since the
                   monitoring system was put into operation in 2016. The largest acceleration recorded on the dam top was
                   8.62gal due to the earthquake dated May 8, 2018 with a Richter magnitude of M3.8. Modal identification
                   of the dam was carried out with the acceleration recorders on the dam of the earthquake based time do⁃
                   main modal identification technique. The results indicate that the first vibration mode is anti-symmetric in
                   arch direction with a characteristic frequency of 1.19Hz, the second one is symmetric at 1.50Hz, and the
                   third one is again anti-symmetric at 1.67Hz. In the higher modes of 2.33Hz and 2.60Hz, the turning
                   points are obvious.
                   Keywords:Xiluodu arch dam; modal parameters; system identification; strong seismic records

                                                                                   (责任编辑:王学凤)




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