Study On Seismic Response Of Submarine Immersed Tunnel Based On Response Deformation Method

As a kind of advanced underwater traffic carrier,immersed tunnel is more and more used in cross-sea traffic engineering because of its advantages of less interference to navigation,flexible section size and so on.Immersed tunnel is built on the underwater soil layer.The waterproof performance is strict.And the immersed tunnel,as the underwater lifeline,will result in extremely serious consequences once the earthquake damage occurs.However,China is located between the two major seismic zones in the world,and the frequency of seismic activity is high.Because of its large intensity,shallow hypocenter and wide distribution,it is a country with severe earthquake damage.Therefore,it is of great scientific significance and practical value to study the seismic response of immersed tunnel.In this paper,a submersible immersed tunnel in China is taken as the engineering background.The seismic response of immersed tunnel is studied as follows:(1)The development history and seismic response research status of immersed tunnel at home and abroad are summarized and the characteristics and research methods of seismic response of underground structures are introduced in detail.The research methods of seismic response of immersed tunnel are summarized.(2)Based on the actual engineering survey and design data,a three-dimensional beam-spring finite element model of the whole longitudinal space is established based on a submersible tunnel project in China.A formula for calculating the longitudinal relative displacement(opening quantity)of pipe joints under seismic action is presented,based on the classical generalized response displacement method and the theory of non-reflective boundary.The three-dimensional finite element model of soil mass at engineering site is established by ANSYS/LS-DYNA software,and the displacement time history response of soil is obtained by free field analysis,and the displacement response of immersed tube tunnel under earthquake action is obtained by inputting displacement wave into beam-spring model.(3)By analyzing the seismic response results under different temperature conditions and different ground motion inputs at the same temperature condition,the dynamic response law of immersed tube tunnel under earthquake action is obtained.(4)By analyzing the seismic response results under different siltation conditions,the dynamic response of immersed tunnel under earthquake action is obtained,and the input direction of ground motion and the stiffness parameters of spring are adjusted.The sensitivity law of opening quantity to ground motion input and soil spring stiffness is obtained by adjusting the parameters,which provides a useful reference and opinion for seismic design of immersed tunnel structure.