| To quickly assess the level of the dam damage after strong earthquake,launch the emergency plan,organize emergency rescue and disaster relief,can greatly reduce risk of the secondary disasters of dam,are necessary means to protect thesafety of the dam and the downstream towns.The main content is how to build dam strong earthquake monitoring and early warning decision support system,based on dam safety monitoring stations’ strong motion records,which integrated technologies including of data acquisition and processing,structure state identification and simulation analysis,seismic hazard investigation assessment,network,GIS,database management,data mining,etc.In the paper,the application status and development trend of earthquake early warning technology and dam strong earthquake monitoring technology were summed up,and the reservoir dam’s strong earthquake safety and emergency support technology related theories and technologies,and theirs engineering application were carried out study.Many theories and technologies were researched which include strong earthquake safety monitoring,data processing,structure modal identification,artificial earthquake wave generation,dam damage investigation and evaluation,etc.These methods and theories had been developed into application software systems Using C++Builder language.Some systems had been successfully applied on dam.The main research contents are as follows:1.Dam strong vibration monitoring and early warning technology were constructed.The main points of strong earthquake data trigger,data acquisition,data analysis,and data management were analyzed.The earthquake trigger algorithm and trigger collection flow were designed.Rapid evaluation software module of strong motion was developed.Information database was planed.Strong motion records data analysis software and the earthquake monitoring and early warning system were developed.According to thedemand of remote management,the network communication protocols of remote management were designed,remote monitoring and management system was developed.The strong earthquake monitoring and early warning system had been put into practical application.A series of functions,relate to database management,strong motion data fast analysis,dam seismic damage coefficient analysis and judgment and remote management system,were achieved.2.Methods to analyze fundamental frequency characteristics and non-stationary response regulars of the dam were proposed.On the basis of analysis some adverse effects such as spectral leakage and barrier effect in Discrete Fourier Transform(DFT)and their causes,a method combined with the average periodogram and ChirpZ transform is proposed,this method can be applied to fundamental frequency characteristic analysis by using pulsation response data.Through the examples showed,it can effectively reduce barrier effect,improve the accuracy of frequency spectrum analysis.Theoretical derivation to modal confusion issues in HHT analysis was done,and the impact of noise on the instantaneous frequency analysis was studied.The improved method of HHT transform based on adaptive band filter was put forward.Numerical examples show that,the method can suppress the mode confusion phenomenon,improve the solution precision of instantaneous frequency.3.ITD and ERA methods were improved.The formula of the normalized modal factors calculation method in ITD method was derived.The modal tracing diagram drawing was realized,which can effectively eliminate the noise and improve the precision of the structure modal identification.A simulation example shows the effectiveness and feasibility of NExT method.The effects of different signal to noise ratio,the effects of different reference channel,and the effects of different window functions,in the NExT method,were analyzed.A method to filter noise modal using noise weight setting,was put forward in the study of ERA method.The effectiveness of the proposed method was verified too.In addition,an artificial seismic wave generation software was developed,which realized artificial seismic wave’s reaction spectrum fitting precision control,and which could generate three directions seismic waves at the same time,and which could analyze the velocity response and displacement response and other functions.On the base of summaring the characteristics and methods of water engineering structure’s earthquake damage survey,dam earthquake damage grade division indexes were proposed,and seismic damage assessment database software was developed.Finally,after Integrating above results,the dam strong earthquake and emergency support system research and design was conducted. |
