Research On Feature Information Extraction And Condition Monitoring Of Flow-Induced Vibration On Arch Dam Structure

The operating environment of the arch dam structure is complex and easily affected by external factors.Various damages may occur under the excitation of current load during long-term use,which will bury hidden dangers for the later safe operation.In severe cases,it may cause structural damage and unforeseen serious consequences.Therefore,ensuring the safe and stable operation of the arch dam structure is the primary task of monitoring its operation status,and secondly,it can also improve the economic benefits of the arch dam structure.In recent years,in order to improve the safety of the structure and the economic benefits of water conservancy projects,the use of dynamic test signals to monitor the operation status of hydraulic structures has been widely used in order to discover the safety problems of the discharge structure in advance and improve the safety level.Monitor and analyze the vibration signal of the discharge structure,comprehensively research and judge,and grasp the operating status of the structure in real time.This paper takes the hydroelastic model of Laxiwa Arch Dam as the research object,and monitors the operation state of the arch dam’s discharge structure based on the measured vibration data.Select the appropriate analysis length of the flow-induced vibration information and extract its operating characteristic signals,construct a damage diagnosis model to monitor and analyze the operating state of the arch dam structure.(1)Selection of data analysis length.Vibration signal data is the key to calculating structural vibration characteristic information,and it is related to the validity of structure monitoring results.This paper proposes a method for determining the optimal analysis length of vibration measurement data based on improved multi-scale permutation entropy.This method is used to reduce the error that may be caused by manual selection of data length.This method is applied to the selection of the optimal data length of vibration signals in simulation experiments and engineering examples.The results show that this method can effectively select a reasonable data analysis length and avoid the loss of characteristic signals caused by artificial selection.(2)Extraction of flow-induced vibration information of arch dam structure.The measured vibration signal of the arch dam structure contains a lot of interference signals such as low-frequency flow noise and high-frequency random white noise.In order to reduce the influence of noise on the vibration signal,a new type of arch dam discharge structure vibration signal noise reduction based on EWT-SVD is proposed.By filtering and reducing the noise of the noisy vibration signal,the signal data reflecting the real vibration characteristics of the structure can be obtained.The calculation results show that the EWT-SVD joint noise reduction method can effectively filter out noise signals,make the structure’s vibration characteristic information more prominent,reflect the true vibration state of the discharge structure,and provide a basis for online monitoring and safe operation of the discharge structure.(3)Evaluation of the risk status of the arch dam structure.The variance contribution rate method is used to dynamically fuse the measured data from multiple measurement points of the hydroelastic model structure of the Laxiwa Arch Dam in order to reflect the overall operating status of the arch dam’s discharge structure.According to the monitoring data of the arch dam structure under different operating conditions,a PE-HMM damage diagnosis model is established.Input the different types of vibration signals of the arch dam discharge structure to obtain dynamic decision results at different times,which can effectively extract the operating vibration characteristic information of the arch dam.Accurately reflect the working status of the arch dam structure,evaluate the current state of the arch dam project,and analyze the gradual change of the arch dam damage trend.It can provide a reference basis for damage diagnosis decision-making and engineering maintenance for large arch dam projects to ensure its safe and stable operation.