基于原型观测的水电站厂房结构振动分析

由于规范中用以计算动位移的动荷载与实际情况有一定出入，为了找出最主要的垂向动荷载，并提出计算厂房结构垂向动位移的方法，根据原型观测资料结合信号分析技术分析了水电站正常运行时尾水脉动、水轮机顶盖压力脉动、项盖垂向振动、推力轴承垂向振动、下机架基础垂向振动和机墩顶部垂向振动之间的位移与频率关系，并详细阐述了水电站厂房结构内的动荷载情况，指出各种动荷载可能产生的作用及影响，对某些荷载的量级做了初步估算，进而找出最主要的垂向动荷载——轴向水推力的脉动．结果表明，顶盖压力脉动与尾水脉动是轴向水推力脉动的主要原因，规范规定的垂向动荷载偏大．最后，基于实测资料对厂房结构进行三维有FIt元反馈分析，提出了一种计算厂房结构垂向动位移的方法。

Structural Vibration of Hydropower House Based on Prototype Observation

To find out the major vertical load and a new method to calculate vertical dynamic displacement,according to observed data of prototype and by means of signal analysis, the relations of displacement and frequency between a series of fluctuations and vibrations during normal operation of hydroelectric station are analyzed, including tail fluctuation, turbine cover's pressure fluctuation, cover's vertical vibration, thrust bearing's vertical vibration, foundation's vertical vibration of lower bearing bracket, as well as pedestal top's vertical vibration. Meanwhile, distribution of various dynamic loads of hydropower plant's structure is presented, and its effects are analyzed. The magnitudes of some loads are estimated. It is concluded that the major vertical load is fluctuating pressure of axial hydraulic thrust, which is mainly induced by cover's pressure fluctuation and tail fluctuation;normalized vertical dynamic load in code is a little bigger than the practical load. Based on measured data, feedback analysis of 3D FEM is used to analyze powerhouse's structure. Furthermore, a new method to calculate vertical dynamic displacement is presented.