Research On Dynamic Response Of Subway Tunnel Lining Structure Under Explosive Loading

In recent years,the subway plays a strong role in transportation.Because of its safety in operation,more and more attention has been paid to it:Therefore,it is necessary to study the dynamic response law of the lining structure of the subway tunnel under the external explosive load and determine its damage degree.Based on the project of Xi'an Metro Line 6,this paper uses ANSYS/LS-DYNA finite element analysis software to establish the analysis model,carries out research and Analysis on the deformation of the supporting structure of the Metro tunnel,and studies the propagation law of stress wave under the near-surface explosion source.By comprehensive analysis of three factors,i.e.different ground side explosion angle,different buried depth of the metro tunnel and different explosive equivalent,the paper studies the external explosion load.The dynamic response law of tunnel lining structure is analyzed,and the damage law of tunnel lining structure is further analyzed.It has high technical,economic and social efficiency.The main conclusions are as follows:(1)Four groups of working conditions are established by studying the lateral blasting angles of near-surface explosion source,which are 0 Top Blasting and 15°?30°?45°respectively.The displacement,velocity and acceleration deformation of tunnel lining structure are studied.The results show that the deformation of tunnel lining structure is remarkable when the angle of side blasting is 150 and 30° and the dynamic response of tunnel lining structure is weak when the angle of side blasting is 45°.(2)When the lateral blasting angle is 15 degrees and the tunnel buried depth is 12 m,15 m and 18 m,the maximum radial displacement of 12 m and 18 m is 9.4 mm and 4.5 mm respectively,which decreases by 49%,and the maximum lateral displacement is 11 mm and 6.5 mm respectively,which weakens by 41%.The dynamic response of tunnel lining structure decreases with the increase of buried depth.Therefore,in the design of tunnel explosion protection,the lining can be reduced by increasing the buried depth of tunnel.Deformation degree of radial and transverse displacement of masonry structure.(3)When the explosive equivalent is 200 kg TNT,300 kg TNT,400 kg TNT and 500 kg TNT,the displacement,velocity and acceleration deformation law of tunnel lining structure are analyzed.It can be seen that the explosive equivalent is the most sensitive variable of explosive stress wave strength compared with the lateral explosion angle and burial depth.When the explosive equivalent is 300 kg TNT,400 kg TNT and 500 kg TNT,the deformation and vibration of tunnel lining structure occur,the equivalent is 3 kg TNT,400 kg TNT and 500 kg TNT.The maximum displacement and velocity of 00 kg TNT are 8 mm and 0.42 m/s,respectively.When the explosive equivalent is 200 kg TNT,the displacement and velocity decreases by 59%and 40%,respectively.No obvious deformation and vibration are observed in the lining structure.(4)In the damage analysis of lining structure,the damage degree of lining structure is analyzed by the principal strain time history curve of joints in special parts of lining structure and the pressure damage diagrams of 2000 and 4000 micros.The local stress state of lining structure is judged by the maximum principal strain time history curve.The results show that the lateral blasting angle will lead to the deviation of the damaged position of the lining structure;the damage effect of the tunnel depth on the lining structure is weakened significantly;the explosive equivalent changes the damage degree of the lining structure.