Analysis Of Mainshock-Aftershock Resistance And Vulnerability Of Subway Tunnel

With the promotion of the 13th five year plan,the construction of urban subway in China has entered a new journey.As a kind of permanent building,the requirement of seismic performance of subway tunnel has become a hot topic.In recent years,the discussion of the main aftershocks has become the focus of the industry experts and scholars.At present,the code for seismic design of buildings published by the state has few provisions on the main and aftershocks,so the research on the main and aftershocks of subway tunnels has become the requirement of the times.Based on a shield tunnel section of Shenyang Metro Line 10 as the engineering background,this paper uses ABAQUS finite element simulation software to analyze the main and aftershock response of metro shield tunnel:(1)Through the elastic-plastic time history analysis and pushover analysis,the synthetic principal and residual seismic waves are applied to the model respectively to verify the applicability and efficiency of pushover analysis.(2)The main and aftershock responses of subway shield tunnel under different conditions are analyzed by changing the relevant parameters of working conditions.(3)The results of time history analysis are used to draw the vulnerability curve to study the exceeding probability of subway tunnel under the action of main and aftershocks.The main conclusions are as follows:(1)The applicability of Pushover Method is proved by comparing the stress response obtained by Pushover Method and elastic-plastic time history analysis.(2)Through pushover analysis,it can be seen that the earliest position to enter the plastic stage and failure stage always appears on the 45 degree and 215 degree segments.(3)With the increase of buried depth,the seismic wave intensity of metro shield tunnel will increase.(4)The bias of subway shield will make the soil on the bias side squeeze the subway shield tunnel obviously,that is,the normal action of the soil will be strengthened,and the shear action will be weakened,which will make the opposite side of the subway shield tunnel produce the opposite effect,and reduce its ability to resist the main and aftershocks.(5)For the same target displacement,the better the stiffness of the soil,the smaller the stress response of the subway shield tunnel,that is,the smaller the disturbance of the surrounding soil to the subway shield tunnel,the better the anti main and aftershock effect of the tunnel.(6)For the concrete grade,it needs to be combined with the specific situation analysis.With the improvement of the compressive strength of concrete,the seismic effect is improved,but the corresponding concrete strain is reduced.(7)The comparison of vulnerability curves shows that the exceeding probability of aftershocks in four Limit States increases by 11.82%,19.4%,20.48% and 39.6% respectively.