Study On Seismic Response Of Subway Tunnel Under Loess Site Condition

In recent years,the construction of subway projects in loess region of central and western China is increasing year by year.Because the loess has the particularity of columnar joint,weak consolidation and seismic subsidence,it increases the seismic disaster of subway underground structure in loess area.Therefore,it is necessary to study the seismic response law of subway tunnel in loess region,which has very important academic significance and engineering application value.In this paper,the dynamic contact friction test of loess--subway tunnel is carried out to systematically study the change rule of the contact friction coefficient between loess and structure,so as to provide a basis for the parameter selection of the dynamic interaction seismic response analysis model of subway tunnel in loess region.Dynamic analysis based on track-train system,train load time history curve of nonlinear finite element analysis software ABAQUS is adopted to establish the metro tunnel structure under the action of earthquake and train load coupling seismic response analysis model,studies the different types of ground motion and working condition of the soil cover thickness and the buried depth of different structure seismic response of the subway tunnel structure under the law.The main research contents and results are as follows:(1)design of loess-metro tunnel dynamic contact friction characteristic test,respectively in different method to stress,the vertical acceleration,moisture content and depth of different tectonic conditions to carry out the indoor experiment study,all the factors of soil-structure the influence law of friction coefficient,optimize the loess ground and the subway tunnel dynamic interaction model of contact friction parameter accessor methods.(2)will be infinitely long beam above the rail system is simplified to a spring,based on Hertz contact theory,the dynamics equation in the process of interaction between wheel and rail and the subway in xian and orbital parameters of train track-train system dynamic analysis,get the train load time history curve,establish loess field under the condition of the subway tunnel under earthquake and train load coupling numerical analysis model of subway tunnel seismic response analysis for loess area to provide a scientific method.(3)based on the established numerical model,different types of ground motion is studied,the structure of the different soil cover thickness and buried depth of the subway tunnel structure under the condition of seismic response characteristics,the earthquake and train load coupling subway tunnel structure under the action of peak acceleration and the maximum horizontal displacement and vertical displacement of the largest seismic response,such as law,points out the subway tunnel structure under earthquake load coupling and train the seismic weak parts,for the loess area,the subway underground structure seismic design and aseismic theory research to provide the reference.