Research On Attenuation Characteristics Of Peak Acceleration Of Vertical Ground Motion In Yunnan Region

Nearly ten years in this paper based on the seismic data collected in Yunnan region,selected 58 earthquakes that met the need of the study,a total of 752 data set of the three-component seismic records,mainly to the vertical ground motion of Yunnan study on discussion and analysis in different situations,study is given priority to with the peak acceleration of ground motion parameters of the following:(1)Firstly,an appropriate ground motion attenuation model is selected.Then,the parameters in the attenuation model are fitted by Levenberg-Marquardt optimization algorithm based on Yunnan seismic data,and the ground motion attenuation relations in vertical and horizontal soil layers and vertical and horizontal rock layers are obtained.Then the obtained attenuation relation and the original data points are used to draw a graph to check the correspondence between the attenuation relation and the scattered points.Finally,the results of attenuation relation are proved to be ideal by residual analysis.(2)By using the data of an earthquake that is not in the sample to test the applicability of the attenuation relation and drawing the comparison diagram,it is found that the attenuation curve has a high coincidence with the actual observation points.Therefore,this attenuation relation can be well applied to the prediction of ground motion in Yunnan region.Moreover,when the vertical and horizontal attenuation curves are compared,it is found that when the magnitude is larger,the vertical ground motion exceeds the horizontal ground motion near the epicenter area,and the vertical ground motion attenuates faster than the horizontal ground motion with the increase of the distance.Then the attenuation relation of this paper is compared with that of other scholars,and there is little difference on the whole,indicating good applicability.Through the above two tests,it is concluded that the attenuation relation in this paper has a good applicability in Yunnan,so it can be used to effectively and accurately predict the ground motion in Yunnan.(3)As for the influencing factors of peak acceleration ratio,this paper analyzed the fitting curve graph and numerical distribution from the three aspects of site,magnitude and distance respectively,and discussed the main reasons for the difference.By comparing with each other,it is pointed out that the current recommended value of0.65 is unreasonable to some extent,so it should be modified according to different situations.Finally,the recommended value of peak ratio in Yunnan region under different circumstances is given based on two different peak ratio attenuation models.(4)To understand the relationship between peak acceleration and earthquake damage,through the earthquake damage index and instrument intensity to Yunnan area of the earthquake risk analysis,pointed out the main earthquake damage and corresponding measures,can be in the future earthquake fortifications and rescue disaster relief plays a great role.