Research On Ground Motion Synthesis Based On The Composite Source Model

In recent years,a number of 200-meter high arch dams have been built in southwest China,and this area is a typical strong earthquake area in China,so it is very important to ensure the seismic safety of high arch dams.However,due to the lack of seismic records near the dam site,the seismic input of engineering seismic analysis cannot be reasonably given.Therefore,seismic research based on fault information is an indispensable part for seismic safety evaluation of high arch dams.Based on the composite source model,this dissertation completes the time-history synthesis of the Jiuzhaigou ground motion in the horizontal direction.At the same time,it is compared with the measured data provided by The China Earthquake Networks Center to verify the feasibility and effectiveness of the composite source model.On this basis,this dissertation deeply studies the sensitivity of regional medium velocity model and the composite source model parameters to the synthesis of Jiuzhaigou ground motion to obtain the optimal parameters to simulate ground motion.The main research contents and results achieved are as follows: 1.The time history information of the horizontal acceleration of ground motion in Jiuzhaigou was collected and sorted out,and the original seismic wave data were filtered and baseline data were corrected through Seismo Signal seismic wave processing software to ensure the accuracy of the comparison data.2.The basic principle of the composite source model is introduced in detail: the layered soil structural model is used to convolve the composite source time function with the Green function calculated by the generalized reflection and transmission matrix method to obtain the ground motion of strong earthquakes.By using a composite source model to simulate the Jiuzhaigou ground motion,and comparing and analyzing the acceleration time-history curve and the Fourier amplitude spectrum fitting effect and overall error of the station,it is concluded that the overall acceleration peak synthesis is consistent with the actual situation,and the local deviation in conclusion.3.Starting from the sensitivity of the input parameters of the composite source model,based on the MATLAB program,the errors of a single station and an overall station under the conditions of different regional medium velocity models,different seismic moments and stress drops were obtained.The effects of these parameters on the seismic synthesis of jiuzhaigou were compared and analyzed.It is concluded that the appropriate parameter values will make the logarithm ratio of ground motion and measured data between-1?1.as a whole,the low-frequency band(less than 10Hz)between-0.7 ? 0.2,and the average horizontal error of 70% stations is less than 0.6.The simulation results get better.Finally,the optimal composite source model input parameters for jiuzhaigou ground motion synthesis are selected.