Study On Seismic Response Characteristics And Shock Absorption Measures Of Tunnels Crossing Karst Area

This paper takes the Wufengshan tunnel in Enshi City of Hubei Province as the engineering background,and based on the ANSYS finite element principle,the dynamic response laws of caverns with different diameters and locations under the earthquake are studied by means of numerical simulation.Based on the seismic damage analysis of the tunnel in the karst area,the advantage of the shock absorber-flexible joint is integrated,and a flexible shock-absorbing structure combining the shock-absorbing layer and the flexible joint is proposed.The flexible shock-absorbing structure is also discussed for the tunnel lining.Damping effect,and optimize its parameters,and finally get the best ratio of flexible shock absorber structure.The main research work is as follows:1.Several key issues,such as the application of viscoelastic artificial boundary,seismic wave selection,time-frequency analysis of seismic wave,and filter processing,were discussed,which ensured the rationality of seismic wave input in numerical simulation.2.The input of seismic waves is implemented by applying equivalent node loads on the artificial boundary of viscoelasticity,and the rationality of the input of seismic waves is verified to ensure the accuracy of numerical simulation.3.A three-dimensional numerical model of the karst section of the Wufengshan tunnel was established,and the acceleration,displacement,stress,internal forces,etc.of the tunnel lining under different cavities under different cavities were studied.Based on this,the karst tunnel was obtained.The dynamic response of the structure.4.Based on the earthquake damage of the tunnel structure in the karst area,a flexible shock absorption measure combining the shock absorber layer-flexible joint is proposed,and the shock absorption effect of the flexible shock absorber structure is discussed.The parameters of the flexible structure(damping layer thickness and joint elastic modulus)were optimized respectively,and the influence of different parameter changes on its damping effect was discussed.