| China is a major water conservancy country with a long history,and the number of water conservancy projects ranks first in the world.With the development of the discharge structure towards high head,large flow,and light weight,the problem of structural damage caused by the strong vibration of the discharge induced by the discharge has become increasingly prominent.Comprehensive control of the vibration hazards of the discharge structure and its safety evaluation are the key issues to ensure the safe operation of the discharge structure.Using the inverse analysis method,using the real dynamic response signals(such as displacement,acceleration response,etc.)of the finite measuring point of the discharge structure under the excitation of the discharge to solve the equivalent load acting on the discharge structure,and determine the overall dynamic response field of the discharge structure It is of great significance to improve the vibration safety control indicators of the discharge structure and provide guidance for the safe operation of the discharge structure.It is also the main content of this paper,which is specifically carried out from the following three aspects:(1)Research on the signal processing method of the vibration response of the discharge structure.Aiming at the characteristics of low signal-to-noise ratio,non-stationarity and randomness of the discharge vibration response signal,a combined CEEMDAN-wavelet threshold noise reduction method for the vibration response signal of the discharge structure is proposed.By constructing an improved wavelet threshold function,the shortcomings of traditional soft and hard threshold functions are overcome,and combined with CEEMDAN,the signal adaptive processing capability is improved to achieve effective noise filtering.Numerical simulation experiments show that the method in this paper has a good signal noise reduction ability,effectively filtering out high-frequency noise and low-frequency noise in the signal,and can be used for noise reduction processing of the vibration signal of the discharge structure.(2)Research on the time domain identification method of the vibration source load of the discharge structure.A mathematical model based on the Duhamel integral for the time domain identification of the vibration source load of the discharge structure is constructed,and Tikhonov’s pre-optimized LSQR algorithm is proposed to solve the ill-posed problem in the time domain identification and inversion of the vibration source load,so as to improve the time domain identification of the vibration source load.Stability and accuracy.Through the establishment of a cantilever beam numerical simulation model to analyze the recognition accuracy of this method under different noise levels,the results show that the method can more accurately identify a single harmonic load and a single random current load under the noise level of 1%and 5%.And multiple random loads lay the foundation for the time-domain vibration source identification of the discharge structure.(3)Carry out vibration source identification of Ertan prototype project.Firstly,the vibration response signal of Ertan arch dam prototype is de-noising by combining ceemdan wavelet threshold to filter the high-frequency noise and low-frequency noise in the vibration response signal of the measuring points.Secondly,based on the de-noising prototype vibration response signal,the time-domain identification method of the vibration source load of the discharge structure is used for inversion,and the results of different operation conditions are obtained The equivalent hydrodynamic load acting on the arch dam is input into the finite element model to obtain the time history of vibration response,and the accuracy of load identification is verified by comparing it with the measured value.Finally,the characteristics of hydrodynamic load are analyzed,and the vibration response law of the dam under the action of multiple vibration sources and single vibration source is studied,so as to provide reference for improving the vibration safety index of discharge structure Theoretical support. |
