A New Artificial Seismic Wave Synthesis Method Based On Continuous Wavelet Analysis

In this paper,one-dimensional continuous wavelet transform is used for a large number of natural ground motion signals,and the continuous 1-D wavelet transform(CWT)diagram is analyzed to explore the time-frequency characteristics of seismic waves in different field grounds.Through the analysis and statistics of a large amount of data,the variation law of the different frequency components of the natural wave in the time domain and the evolution of the scale at different times are summarized.On this basis,the relationship between the shear wave velocity and various features is mapped.By comparing existing artifi cial seismic wave synthesis methods,and based on the obtained features,combined with the inverse transformation of one-dimensional continuous wavelet transform,a new artificial seismic wave synthesis method is proposed.Artificial waves designed to be s ynthesized can be more closely fitted.Site soil conditions and actual ground motion characteristics.First of all,we analyze the synthetic methods of the existing artificial seismic waves and analyze the limitations of the traditional methods.It is proposed that the synthesis method based on one-dimensional continuous wavelet transform and inverse transform can overcome the original limitations to a certain extent,which makes artificially synthesized seismic waves closer to natural waves.Then,the principle of one-dimensional continuous wavelet transform and inverse transform is given,and the advantages and necessity of analyzing natural seismic waves using one-dimensional continuous wavelet transform are given.The feasibility of feature synthesis artificial wave based on CWT diagram is analyzed.Then,the CWT maps of different natural seismic waves are calculated and statistically obtained,and the effective starting position and peak position of the scale data at different times are determined.As for the extraction of the above curves,the upper and lower bounds of the curve distribution under the respective site types are retained.Then by statistically analyzing the waveform data of soil types at different sites,we can obtain the evolution rule of the mid-scale of the CWT map of seismic waves at different times under different site conditions,and extract the peak curve.Subsequently,by analyzing the effective duration of different scales,the law of the duration and attenuation of different frequency components in different seismic waves over time is obtained.The characteristics of the CWT maps of the four types of sites can be obtained through statistical means.Then the above features are numerically fitted according to actual needs.Based on this,the relationship between the shear wave velocity and various types of features is preliminarily established.Using the obtained feature information,the wavelet inverse transform can be used to obtain an artificial seismic wave based on the CWT map.Finally,the rationality of the artificial wave synthesised by the new method is determined by solving the power spectrum of the new artificial wave,comparing the artificial and natural waves of the old method with the target power spectrum.At the same ti me,one-dimensional continuous wavelet analysis was performed on these three types of seismic waves to extract features of the related CWT maps.Comparing the corresponding characteristics of the newly synthesized artificial wave with the natural wave of the same kind and the artificial wave of the old method,the fitting degree of the artificial ground motion signal of the artificial wave with the new method and the artificial wave of the old method in the time and frequency directions is determined.The new synthesis method is based on waveform data obtained from two aspects of the time domain and frequency domain.The existing artificial seismic wave synthesis methods are well fitted to the natural wave's non-stationary time domain characteristics and simple frequency domain.Characteristics,but the modulation in the frequency domain is generally uniform and does not fit well with the non-stationary nature of the natural frequency domain.The method proposed in this paper,taking into account the frequency characteristics,carefully considers the time-varying characteristics of different frequency components of the natural wave.The results show that this method can better match the characteristics of natural seismic waves.At the same time,by using certain mathematical means,various types of features are mapped from the four categories of site classification to the specific site soil shear beam,so that a certain degree of detailed fitting of site soil and other conditions can be provided,and a kind of Artificial wave synthesis method that can better match natural ground motion and actual site conditions.