Analysis Of Seismic Performance And Influencing Factors Of Immersed Tunnel Based On Improved Generalized Reaction Displacement Method

As a kind of large-scale vehicle traffic crossing water field,immersed tunnel has been more and more built in cities around our country.Although the history of immersed tunnel is over a century,immersed tunnels' seismic resistance only has been studied for 3 decades.Due to the special property of underground structure,immersed tunnels are not easy to be destroyed by earthquake.But because of the unique function of immersed tunnel,once they collapse,the damage to human lives and the financial lost will be innumerable.Besides,most immersed tunnels in our country were built in prosperous cities along the coastline,located in a seismic belt and lying on soft soil,so doing the research of immersed tunnels' seismic resistance satisfies the requirements of development and has significant practical values.This article based on general response displacement method,analyses the seismic response of a real immersed tunnel and acquired the following achievements.(1)Considering the geometric size of tunnel and modeling the joint more precisely,improved the beam-springs model on generalized response displacement method.(2)Summarize the steps of generalized response displacement method and modeling ways on FEM analysis software,including the specific operation on key steps.(3)According to the analysis of a real immersed tunnel,the seismic responses of segments lying on hard soil are small and their joints' open widths show no relativeness to any force component.On the other hand,the seismic response rises dramatically on the segments through different soils and the open widths of joints lying on soft soil are highly positively relative to tension.(4)By controlling which motion inputted into the model,research in seismic vibration components ' influences on segment joint's open widths were done.Found that input vertical motion could raise the open width by about 5%.And the open width caused by dual horizon motion is 23% larger than by single longitudinal motion.(5)Comparing the multi-support excitation and the identical excitation's tunnel response,deduce that the multi-support excitation will cause greater damage to immersed tunnel.