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Field Vibration Tests and Proposition of Safety Measures for Dynamic Instabillity of Folsom-Dam Tainter-Gate

Folsom-Dam Tainter-Gate 动态失稳现场振动试验及安全措施建议

基本信息

批准号：
15360127
负责人：
ISHII Noriaki
金额：
$ 8万
依托单位：
Osaka Electro-Communication University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2004
项目状态：
已结题

项目摘要

Tainter gates (radial gates) are frequently used as a crest gate of dam for a flood release. A huge Tainter gate installed on Folsom dam in California, induced vibrations and failed, early in the morning of July 17,1995. A possibility that vibration participated in its failure was pointed out from just after the accident, and some failure analysis studies have been performed by applicants.In this study, verification studies of theoretical analyses developed for a possible coupled-mode flow-induced vibration of Tainter gates were made by conducting vibration tests for 45-ton Tainter gate and 3-D 1-13-sclaed model gate. In addition, failure analyses of Folsom dam Tainter gate were made and suggestions for dynamic stability were presented. Research results are summarized as follows :1.Field vibration tests of Folsom-dam Tainter-gate which was being planned to conduct at the beginning of this research project was not able to be conducted because of severe cautions to terrorism in USA. In t … More his study, thereupon, field vibration tests were conducted for a 45-ton full-scale gate under practical uses in Japan, to determine its in-air and in-water natural vibration characteristics, where steel bar breaking tests were first adopted to excite the huge gate to vibrate. Detailed measurements of responding vibration acceleration were made to identify the frequencies and modes of natural vibrations. In in-water vibration tests, hydrodynamic pressure also was measures, where a small pressure hole was made directly through the skinplate. The measured data were incorporated into the theoretical analyses to calculate the in-water vibration frequency and the dynamic instability curve. As a result, the theoretical analyses were well verified for its validity.2.Three-dimensional 1/13-scaled model of Folsom dam Tainter-gate was made, where the vibration modes and its in-water vibration frequencies were carefully designed to be exactly same as those of failed Folsom Tainter-gate. The 3-D model gate was installed in a large flume of water circulation type. As a result, the 3-D model gate definitely re-realized the same type of violent coupled-mode self-excited vibration that must have caused the Folsom gate failure. The theoretical analyses were well verified for its validity by the 3-D model gate tests also.3.Folsom gate Failure was made by applying the developed theoretical analyses, where the dynamic instability of the Tainter-gate is theoretically examined and the major characteristics of this instability were presented, and an FEM analysis of the structure was incorporated to reveals that the small vibration amplitude of at most 11.9mm at the spanwise center and bottom end of the skinplate induced the excessive hydrodynamic pressure load of about 1.6 times the static load, thus causing incipient failure of 4 bolts connecting a diagonal member to the main struts. Less

弧形闸门是大坝泄洪时常用的一种闸门。1995年7月17日清晨，安装在加州福尔松大坝上的一个巨大的泰恩特闸门因振动而失效。从事故发生后不久就指出了振动参与其失效的可能性，申请人进行了一些失效分析研究。在本研究中，通过对45 t Tainter闸门和3-D 1-13-scaled模型闸门进行振动试验，对Tainter闸门可能的耦合模态流激振动的理论分析进行了验证研究。此外，还对福尔松坝弧形闸门进行了破坏分析，并提出了动稳定性建议。主要研究成果如下：1.由于美国对恐怖主义的严重警告，本研究项目开始时计划进行的Folsom-dam Tainter-gate现场振动测试未能进行。在t ...更多信息为此，在日本对一座实际使用的45 t足尺闸门进行了现场振动试验，确定了其在空中和水中的自振特性，首次采用断筋试验激发巨型闸门振动。通过对响应振动加速度的详细测量，识别了结构的固有振动频率和振型。在水中振动试验中，还测量了动水压力，其中直接通过蒙皮制造一个小压力孔。将实测数据与理论分析相结合，计算了该结构在水中的振动频率和动力失稳曲线。2.建立了福尔松大坝尾门的1/13缩尺三维模型，设计了与失效福尔松尾门完全相同的振型和自振频率。三维模型闸门安装在大型水循环水槽中。因此，三维模型闸门肯定重新实现了相同类型的强烈耦合模式自激振动，必须导致福尔松闸门故障。理论分析的有效性也通过三维模型闸门试验得到了很好的验证。3.应用所开发的理论分析进行了Folsom闸门失效分析，从理论上研究了Tainter-gate的动力不稳定性，并给出了这种不稳定性的主要特征。结果表明，在蒙皮板的展向中心和底端处的最大振幅为11.9mm，流体动压载荷约为静载荷的1.6倍，从而导致将对角构件连接到主支柱的4个螺栓的初期失效。少