Research On Adaptive Baseline Correction Method For Horizontal To Strong-motion Recording

Strong-motion records have gone through nearly a century of development from analog recording to digital recording.Strong-motion recording data processing is one of the most important steps to remove accurate errors from recording to obtain accurate motion information.Baseline correction is a key part of strong-motion data processing.The baseline correction method has a huge impact on obtaining permanent displacement from strong-motion records.The existing methods have developed some self-adapted methods from the earliest subjective experience methods,but there are still some uncertainties in the acquisition of permanent displacement,and the calculation efficiency needs to be further improved.Based on the large number of near-field strong-motion data obtained from the three typical large earthquake events of the Chi-chi earthquake,Wenchuan earthquake and Nepal earthquake,combined with the existing research results,the influence of parameter selection on the results in the baseline correction method is given in three typical earthquakes.The horizontal displacement of the near field station is permanently displaced.The main work of this paper is as follows:In this study,the existing methods are summarized and compared.The existing research on the cause of the existing baseline offset can not produce exact results.The processing criteria of the existing methods are summarized.It also discusses the shortcomings of the existing methods.The existing baseline offset processing methods can be divided into three methods: filtering method,baseline simulation method and experimental method.Among these three methods,the baseline simulation method is the most widely used,and the data processing effect is the best.The baseline simulation method is divided into single-parameter method,two-parameter method and multi-parameter method.Each of the three methods has advantages,and the single-parameter and two-parameter methods are the most widely used.The single-parameter method has high processing efficiency and simple use,and the two-parameter method has good processing effect and is convenient for automatic processing.Based on the existing methods,this paper focuses on the basic physical properties of horizontal permanent displacement,and proposes a processing method based on multiple corrections of angle change.The MATLAB program is used to divide the records to be corrected into multiple different correction intervals.Sub-correction and probabilistic analysis of the results.A relatively determined horizontal permanent displacement is obtained and a final corrected strong vibration acceleration record is obtained based on the permanent displacement.The influence of interval division and fitting on the results in the method is analyzed,and the selection of the parameters of the final correlation method is determined.According to the analysis of the processing of two typical stations TCU079 and 051 WCW,the optimal number of segmentation of the single parameter fitting segment is 17 in this study,and the boundary effect of the first and last tails should be considered in the calculation to remove the two minimum segments.The probability distribution fitting method can effectively obtain the permanent displacement value of a certain angle.A sinusoidal fit to the permanent displacement values for all angles effectively removes errors in permanent displacement values at a single angle.Finally,the application of a large number of typical near-field strong-motion records acquired in several earthquakes such as Chi-Chi earthquake,Wenchuan earthquake and Nepal earthquake shows that this method can effectively obtain effective baseline correction for strong-motion records.Accurate permanent displacement.The calibration results of eight near-field stations in the Chi-Chi earthquake show that the method has great advantages in the application of horizontal to permanent displacement.The results of the correction of 37 stations in the Wenchuan earthquake are not all consistent with the existing research.The reason is that the application of this method has more stringent application assumptions,and in a few cases,the strong-motion record obtained by the near-field stations cannot satisfy the application hypothesis of the method.The application of the earthquake in Nepal shows that the method needs to take into account the nonlinear effects induced by the site when using the soft soil site,although the sinusoidal fitting method can obtain the horizontal displacement of the near-field station with reference value.The correction method for nonlinear baseline offset remains to be further studied.Based on the application analysis of the above three typical earthquakes,this method has a good application prospect in the study of the near-field Horizontal strong motion to permanent displacement,but in some special cases,the correction method still has some limitations,in the fitting correction method.There is still room for improvement.