Study On Dynamic Characteristics And Damage Identification Of High RCC Dam Of Discharge Excitation

In recent years,with the rapid development of roller compacted dam technology,a batch of high RCC dam of 100 meters has appeared in China.However,due to the characteristics of RCC dam construction,many weak stratification structures will be formed on the dam body.Therefore,it is important to study the dynamic response and damage identification of RCC dam under discharge excitation.In this paper,the high roller compacted concrete dam about that the law of structure induced vibration in multi damage condition or layered structure model simulation or filtering noise reduction and modal identification of measured response signal or dam damage identification method is studied by means of numerical model simulation,physical model test and theoretical method improvement.This article main research content is:1)By means of numerical simulation,two kinds of damage were simulated by means of reduced elastic modulus,contact element and so on.The formula of pulsating pressure load for pulsating power spectral density inversion is deduced.The measured main power frequency spectrum is 0.322 Hz and the main frequency is 0.313 Hz.Thickness,layer number and other parameters,and found that 10% reduction in elastic modulus,thickness 1m,layer number 8,the dynamic displacement of the dam is the largest root mean square.At last,four kinds of damage models are established.It is found that the law of the arch crown and crest of different damage models is the same as that of the non-damage model,and the two kinds of damage will affect each other and increase the displacement response.2)The hydroelastic model is an effective method to study the dynamic characteristics of dams.This paper summarizes the characteristics of six laminated layers and puts forward three simulation methods based on the rubber bonding mechanism.The results show that the three-phase mode has a phase change of 6.073 Hz,the fundamental frequency of 6.078 Hz is lower than that of the non-destructive specimen,6.473 Hz,but the mode factor increases.And finally,a hydroelastic physical model with stratified structure was established according to the simulation method.3)In this paper,based on the shortcomings of the previous methods of filtering noise reduction,a combined filter denoising method based on CEEMD and wavelet packet threshold is proposed.The signal-to-noise ratio SNR13.006,The correlation coefficient of 0.9747,the best noise reduction.(ERA/DC)is introduced into the mode identification of the discharge structure.The numerical verification of the cantilever beam shows that the recognition error is less than 2%.The combined method of noise reduction and modal identification is applied to the measured signal of Jinping arch dam,and good results are obtained.At the same time,the fundamental frequency and the time-domain recognition result of the wet-dry mode are consistent.4)The rolling layer is the thin and soft link of the RCC dam.In this paper,a variety of dynamic fingerprint technology for dam layer and crack damage identification.Based on the Bayesian fusion theory and the identification of dynamic strain response by numerical simulation,five or more fingerprints are needed to make the correct judgment result of the measuring points 3 and 4 over 90%,while the identification of fracture damage is achieved by four fingerprints And at the same time,the probability of identification of 11 measuring points which is prone to misjudgment is reduced to below 12.1%,which increases the accuracy of recognition.