关键词: 山岭隧道, 振动台模型试验, 仰坡坡度, 动力响应

Abstract: The tests arrangements are systematically introduced firstly, including test facilities, similar ratios, modelling materials, model cases and so on. Then, the test results including accelerations of surrounding rock and tunnel structure, laws of strains and deformations of structures, failure features of upward slope. The analysis results show that: an amplified effect of acceleration and displacements of tunnel structures exist at the area which is of some distance from the entrance of the tunnel. There is not much differences in the law of the amplification effect for different gradients of upward slope. The amplification effect decreases as the gradient of upward slope increases. The analysis of the strain show that the tunnel structure is mainly subjected to transverse stress. A cycling load of tension and pressure acts on the cross-section of the tunnel which result in additional seismic bending moment on arch waist and arch feet, which could be seen as weak parts in seismic design of lining structure. The mechanical characteristics of lining has no relation with the gradient of upward slope. The additional moment is proportional to soil thickness and the inertia force of lining. As the gradient of upward slope increases, the soil-structure interaction effect is gradually weakened; and the failure modes of the slope are different, which include local slope collapse, large slump at the top of the lining, highstand sliding. Both of them are all the surface failure. But the tunnel openings are usually partially or completely buried, which severely affect the normal use of tunnel. Tests results provide references for seismic design of tunnel portal section in mountain tunnels.

Key words: mountain tunnel, shaking table test, gradient of upward slope, dynamic response