Numerical Analysis Technology Of Seismic Response Of Rock Mass Tunnel Concrete Structure And Its Seismic Response Law

In order to alleviate a series of social problems brought about by urbanization and modernization,the development and utilization of underground space has become a new idea when it comes to the problem of building a construction.With the promotion of a series of major development strategies like "12th Five-Year Plan",the construction of China’s underground structure shows a steady growth trend.At the same time,the results of seismic research on underground structures in recent years show that even underground structures that are surrounded by rock and soil may also suffer serious seismic damage.Therefore,the seismic study of underground structure is important and necessary,and the seismic response of related underground structure under the action of earthquake is also an important research topic.In order to analyze the influence of different seismic conditions on the seismic response of underground structures and summarize the seismic response law of underground structures,this paper adopts the time-range analysis method and reaction displacement method stipulated in the Seismic Design Standard of Underground Structures for the concrete structure,and relies on ABAQUS finite element software to form a set of numerical analysis and modeling techniques for seismic response analysis of underground structures,including the establishment of three-dimensional consistent viscosity elastic boundary,the use of odb file method balanced the ground stress,reasonable input of seismic waves,material parameters,according to certain principles of grid size,etc.Through numerical simulation methods,considering the seismic wave incident direction,site conditions,seismic intensity,tunnel depth,tunnel location and other factors on the seismic response law of underground structure.The following conclusions are drawn:(1)Among the three directions along the horizontal,vertical and vertical direction of the tunnel,model shows the most obvious seismic response when the seismic wave shots in the vertical direction of the tunnel.With the maximum main pull stress as the indicator,the seismic response of the structure can reach 3.65 times the corresponding value in other directions when the seismic wave is incident in the vertical direction of the tunnel.(2)The middle section of the tunnel model is basically consistent with the seismic response law of the mouth section of the tunnel model,when the stress response is the indicator,the seismic response of the middle section of the tunnel is larger,and when the displacement response is the indicator,the seismic response of the tunnel port is greater.The maximum main stress difference of each observation point is 7.1193 Mpa,and the maximum displacement difference is 44 mm.(3)The seismic response of the structure is related to the site conditions,when other conditions are the same,the structure will produce a more obvious seismic response under the condition of the lower perimeter rock grade.Taking this model as an example,the maximum main pull stress extreme value of the structure under the strong weathered granite site is 3.36 times that of the peat site.(4)To study the influence of buried depth on structural seismic response,it is necessary to consider the location of the distance structure of the source,and as far as the analysis results of this paper are concerned,the seismic response of deep buried tunnels is greater.Buried depth increased by 30 m,the maximum main pull stress of the structure increased by1.3446 Mpa,and the displacement value of the tunnel base plate increased by 34 mm.(5)The seismic response of the structure increases with the increase of seismic intensity,which is mainly reflected in the stress and acceleration in the earthquake response.Taking this model as an example,the maximum main pull stress value and acceleration maximum value under the extremely rare seismic conditions are about 5 times the corresponding value under the multi-event seismic conditions at the observation point where the seismic response changes the most under different intensity conditions.(6)Reaction displacement method I is suitable for application to the two-dimensional lateral seismic response analysis of underground structure,the main factors affecting its calculation accuracy are ground-based spring spacing,ground-based spring stiffness determination method,inertial force application method,etc.