Seismic Response Of Metro Tunnels By Viscous-spring Artificial Boundaries

Subway is an effective way to ease the pressure of urban traffic, in recent yearsthere have been expanding subway construction in our country. The Great HanshinEarthquake makes people understand of the seismic safety of underground structures.So the subway underground Seismic Research has great significance.Using the finite element method, this paper studied the layered space base pairsalong the subway tunnel surface ground motion response. First applying viscoelasticartificial boundary on the interception soil medium boundary and derived by applyingthe artificial boundaries of ground motion excitation equivalent nodal force formula.The linear analysis of the layered sheet free field response has been got, and thengiving a linear containing double tunnel layered site seismic response of the groundsurface. This paper writes the equivalent linear method iteration procedure, and thengives nonlinear layered double tunnel with free venues and sites on the surface layerof ground motion response.The results show that because of the presence of the tunnel structure, surfaceresponse is completely different from free-field response. In linear analysis, includingtunnel construction site in the plane perpendicular to the incident under the action of Swaves, surface amplitude of the response was significantly greater than the free-fieldresponse,In the nonlinear analysis, by comparing the results with the linear responsefound in surface decreases predominant period side of the phenomenon.