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Abstract The portal section of mountain tunnels was simplified into a slope with single free face based on the theory of elastic wave. The effect of wave reflection was considered to deduce the solution of free field ground motion on the axis of tunnel under incident SH wave. The 3D shell theory was employed to provide earthquake- induced strains. Shaking table tests were conducted for the portal section of tunnel to validate the theoretical solution. The dynamic response of lining was regarded as the superposition of the ones in cross section and in axial direction. The shearing deformation occurs in the cross section of tunnel under action of SH wave propagating parallel to the cross section. The arch spandrel and arch springing can be seen as the weak parts in seismic design of lining structure. As the distance to the tunnel portal increases，the deformation effect increases slightly. The shearing deformation occurs in longitudinal direction under the action of SH wave propagating parallel to the axial direction of tunnel. The deformation effect is gradually weakened. The dislocation occurs easily at the position of construction joint of tunnel portal due to longitudinal SH wave. Therefore the seismic design in longitudinal direction of tunnel is also worthy of consideration.
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Received: 03 December 2013
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2015, Vol. 34 
