Analysis Of The Influence Of Circular Lining Tunnel On Dynamic Response Of Nearby Site Under Cylinder SH Wave

With the rapid development of urban transportation and the demand for designed buildings on the ground,the large-scale development of urban underground space has become an inevitable trend of urban construction.During the propagation of seismic waves,the existence of underground structures will affect the design ground motion near the surface,which will affect the seismic safety and durability on existing buildings near the surface of the Earth's surface.Therefore,a series of scattering problems caused by the propagation of elastic waves,especially the problem of dynamic response under local site conditions,which should become an important part of basic scientific research.However,most of the existing research results have focused on the dynamic response of the structure itself,and the influence of the structure on the surface ground motion,which is not well considered the influence of the underground structure on the dynamic response of the original site,especially the dynamic response of the underground soil.Therefore,the scattering problem of the elastic half space with a single circular lining tunnel and a double circular lining tunnel under the action of the cylindrical SH wave is studied.The change situation of dynamic response of the surrounding soil around the circular lining tunnel under different parameters along the depth is analyzed in detail.In this study,the current research status of the propagation characteristics and scattering problems of elastic waves in a semi space medium are described at the beginning,and the basic theory of elastic wave propagation in foundation and the methods to solve different problems are briefly introduced.Secondly,the scattering problem of cylindrical SH waves with a single circular lining tunnel and a double circular lining tunnel in the elastic half space is analyzed by using the wave function expansion method.The displacement analytical solution of elastic half space medium and lining medium with circular lining tunnel are obtained,and the correctness of the solution is verified.Through theoretical analysis and ABAQUS finite element analysis,the effects of the dynamic response of the site near the tunnel with circular lining are studied with parameters such as material properties,geometric dimensions and load characteristics,and the variation of the displacement amplitude of the soil around the circular lining tunnel along the depth is mainly analyzed with parameters such as the modulus ratio of the lining of the surroundingrock,the depth of the tunnel,the radius of the tunnel,the distance of the tunnel center and the incidence frequency.Finally,based on the analysis of numerical examples,some important conclusions about the dynamic response of the site near the tunnel in the elastic half space when the cylindrical SH wave propagates along the depth direction are obtained.(1)The displacement amplitude of the soil around the single circular lining tunnel decreases with the increase of the lining stiffness and the buried depth of the tunnel,and increases with the increase of the tunnel radius.(2)The displacement amplitude of the soil around the horizontal parallel double circular lining tunnel decreases with the increase of the lining stiffness and the buried depth of the tunnel,and increases the increase of with the center distance of the tunnel and the incident frequency.(3)The displacement amplitude of the soil around the vertical parallel double circular lining tunnel decreases with the increase of the lining stiffness,the tunnel depth and the center distance of the tunnel,and increases with the increase of the incident frequency.This not only provided new ideas for the study of the dynamic response of the site medium,but also expanded the scope of its theoretical research.It also provides important theoretical guiding significance for the evaluation of earthquake safety and durability of underground structures,such as tunnels and pipes below the surface,as well as the seismic fortification of the nearby construction projects.