Analysis of the Influence of Seismic SV Wave Incident Angle on the Dynamic Response of Inland River Immersed Tunnel Structure
In order to deeply understand the seismic effect of inland river immersed tunnels,the dynamic response of immersed tunnels under oblique incidence of SV waves is studied.Based on the time-domain finite element method and viscous-elastic artificial boundary,the ground motion input is transformed into the equivalent node load to realize the oblique incidence of seismic SV waves.The accuracy of the method is verified by a numerical example.A 2D finite element model of immersed tunnel is established by the Honggu immersed tunnel project in Nanchang to study the impacts of different incident angles of SV wave on the dynamic response of immersed tunnels.The results indicate that the seismic response at the top of immersed tunnels is greater than that at the bottom under the effect of SV wave.The deformation of the middle partition wall is larger than that of the side wall.The riverbed surface will pro-duce settlement deformation;The oblique incidence makes the symmetrical immersed structure produce asymmetric internal forces.With the increase of incident angle of SV wave,both the vertical seismic effect of immersed tunnel and the settlement deformation of riverbed surface increases significantly,while the horizontal seismic effect de-creases.The one of SV wave incident angle changes on the horizontal seismic effect is relatively more limit than the vertical one;The weak position of immersed tunnels mainly occurs at the corners and the junction of the intermedi-ate partition with floor and roof.The seismic design should focus on the structural bearing capacity of these parts as well as the influence of oblique incidence.
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