Analysis Of Ground Motion Characteristics Of Lower Hutt Basin 3D Complex Engineering Site In New Zealand

It is critical procedure to predict ground motions in large-scale complex engineering sites for determining the amplification effect of ground motion.The amplification of ground motions is of great significance to the seismic design of engineering.Limited by computing techniques and means,only 1D and 2D simplified numerical models are often established before to predict the amplification effect of ground motion in complex engineering sites.The predicted results are not enough to reflect the impact of complex sites on the surface seismic response reasonable.It is one of the key problems to improve the seismic fortification and design level to realize the reasonable prediction of the ground seismic characteristics of 3D large-scale complex sites.Based on "Tianhe-2" supercomputer and the Open MP parallel computing technology,the 3D site seismic response program independently developed by the single computer is successfully transplanted to the supercomputer,and is successfully realized the parallel computing function of all 24 processor cores on a node.The computing efficiency and scale of the original program are improved greatly.The improved program makes it applicable to analyze large-scale 3D complex site seismic response.The Lower Hutt basin in New Zealand including frequent seismic disasters and abundant seismic strong motion records is slected as the research object.Based on the geological exploration data provided by the New Zealand Institute of Geology and Nuclear Science(GNS),a 3D finite element model of the basin is established to predict various seismic responses of this basin.In accordance with the results,the basin effect,seismic response characteristics and surface amplification characteristics of the basin are discussed.The main work of this thesis is as follows:1.The application of existing parallel computing in complex engineering site analysis is summarized,and the research results of various basin surface wave effect,focusing effect and edge effect are summarized.2.Using the Open MP parallel computing technology,the existing serial program based on the 3D time-domain explicit algorithm and the transmission artificial boundary is rewritten to make it run successfully on the "tianhe-2" supercomputer.The parallel efficiency and rationality of the program are tested.3.The 3D finite element model of Lower Hutt basin in New Zealand is established to study the basic characteristics of Lower Hutt basin,mainly including the dispersion characteristics,the surface wave effect,focusing effect and edge effect of the basin.4.Based on the geological disaster information network of New Zealand,three actual seismic records of small,medium,large are selected to determine the earthquake input,and the surface seismic response of the observation station is predicted.The prediction results are compared with the actual observation records to study the prediction ability of the model established in this thesis.5.The surface response at the selected representative output points of the surface responses are predicted based on 3D and its corresponding 1D model.The difference of the transfer function and acceleration response spectrum between the 3D model and the traditional 1D model are discussed,so as to provide some suggestions and references for the seismic fortification of engineering structures.6.The main research contents and conclusions of this thesis are summarized,and the shortcomings of this thesis and the prospect of future research are put forwarded.