中文摘要：

为探讨穿越软硬突变地层盾构隧道纵向地震响应特性，基于纵向等效刚度模型，开展几何相似比为1：40的振动台模型试验，研究软硬突变地层加速度以及隧道结构加速度、应变响应频谱特性，并采用数值模拟手段对试验结果进行验证。试验及计算结果显示：软硬突变地层及赋存其中的隧道结构加速度响应频谱曲线吻合较好，均表现出“双卓越频率”现象；输入地震频率接近坚硬地层主频时，软硬突变地层加速度放大倍率随埋深减小不再单调递增；软硬突变地层中结构应变显著增大，最大应变出现在地层软硬交界面软土一侧，隧道纵向应变增大区域分布于软硬地层交界面两侧2．5～3．5倍隧道直径范围内；应变响应从大到小依次为拱项、拱底、拱腰，地层突变处隧道断面顶底应变差以及两侧拱腰应变差较均匀地层显著增大，软硬突变地层不仅增大了隧道纵向内力，也改变了其纵向整体弯曲方向。研究结果将为进一步揭示盾构隧道纵向地震响应特性及盾构隧道纵向抗、减震设计提供有益参考。

英文摘要：

In order to investigate the seismic response of shield tunnels in the longitudinal direction cross the soft-hard stratum junction, a set of shaking table tests with geometric similarity ratio 1 ： 40 were carried out based on the equivalent longitudinal stiffness model. The spectrum of the acceleration response for both the strata and the tunnel structure were studied as well as that for the tunnel strain. The test results were compared with the numerically calculated ones. The results show that the spectrum properties of the acceleration response for the soft-hard junction stratum and the tunnel coincide with each other well, and both exhibit the double predominant frequency. As the depth of the soft-hard junction stratum decreases, the acceleration does not increase monotonically when the excitation earthquake frequency approaches the predominant frequency of hard stratum. The strain of the tunnel in the soft-hard junction stratum increases significantly and the maximum strain occurs on the soft side of this stratum. The enlarged longitudinal strain area of the tunnel distributes within the scope of 2.5 -3.5 times of the tunnel diameter on both sides of the strata interface. The strain of the tunnel in each cross section arranges in a descending order as crown arch, inverted arch and side-walls. The strain difference between the crown and inverted arch as well as between the side-walls increases obviously compared to that in the uniform stratum. The soft-hard stratum junction not only enlarges the longitudinal internal force of the tunnel but also alteres its longitudinal bending direction.