Seismic Response Of Underground Structure Under Non-uniform Seismic Excitation

With the increasing scale of domestic underground structures development and construction,the size of underground structures tends to be large and complicated.The size of the traditional underground structure is small,which is less affected by the site effect and the spatial effect of the ground motion,thus ignoring the influence of the spatial effect of the ground motion.However,due to its size,the large underground structures may be affected by the change of surrounding soil characteristics and the spatial effect of ground motion.Therefore,the seismic response law of long and large underground structures should be considered from the aspects of ground motion input and soil layering characteristics,especially for seismic response law of large underground structures and soil under complex site conditions and under non-uniform input is worthy of discussion and summary.In this paper,combined with the engineering background of a large-diameter shield tunnel,the large-scale tunnel is taken as the research object,and the multi-point non-uniform ground motion input is combined with the seismic response analysis of the large-scale underground structures.Considering the changes of soil characteristics,multi-point non-uniform input mode and ground motion input direction,the seismic response law of underground structures and soils under homogeneous and complex site conditions with multi-point non-uniform excitation is explored.The work carried out by the thesis and the innovative achievements obtained are:1.The research status of seismic response of underground structures under uniform excitation,multi-point spatial ground motion synthesis method and seismic response of underground structures under multi-point non-uniform excitation are summarized systematically.The key problems of seismic response research of underground structures are summarized.The key issues of seismic response research of underground structures are summarized.2.The basic parameters,models and methods of synthesizing multi-point spatial correlation ground motion are expounded.Based on the classical multi-point spatial ground motion synthesis method,the multi-point ground motion synthesis and batch processing program is compiled by Matlab platform,and multi-point ground motion is synthesized as input.3.The seismic response law of the double-layer homogeneous soil free field under the horizontal and vertical non-uniform excitation input is explored,and the seismic response of the soil under the four waves of uniform wave,traveling wave,coherent wave and coherent traveling wave is compared.4.The seismic response law of the two-layer homogeneous soil-tunnel system under the horizontal and vertical non-uniform excitation input is explored,and the influence of the tunnel on the soil response in the presence of the tunnel is compared with that of the free-field condition.The seismic response differences of tunnels under four waves are also compared.5.On the basis of the two-layer homogeneous soil-tunnel system,considering the change of soil characteristics along the input direction of the upper soil layer,the seismic response law of the complex layered soil-tunnel system under longitudinal nonuniform excitation is explored.The seismic response difference of soils with different characteristics under four longitudinal input are compared.The seismic response difference of tunnel indifferent soils under four longitudinal input are also compared.Finally,the research work in the paper is summarized,and the content and direction of the further research are discussed.