强震作用下洞口软硬岩层接触带隧道震害机理研究

强震作用下洞口软硬岩层接触带隧道极易发生严重破坏，揭示该部位隧道的震害机理并构建高效的抗减震措施是隧道安全运营的重要保障。由于软硬岩层动力特性差异较大，地震作用下软岩-硬岩界面非连续变形行为显著，软硬复合岩体-衬砌动力相互作用极为复杂，导致软硬岩层接触带隧道的震害机理尚不清晰。本项目拟开展软硬岩石的动态压缩及软岩-硬岩界面的循环剪切试验，研究岩石的动力特性及循环剪切过程中界面的磨损演化机理，建立软岩-硬岩界面的动态本构模型；开展软硬岩层接触带场地地震响应的数值仿真技术研究，开发软岩-硬岩界面动力特性的数值模拟程序，提出考虑界面与行波效应的非一致地震动输入方法；结合依托工程，开展多台联动振动台试验与数值仿真，探究地形、地质及地震动条件对隧道响应的影响规律，揭示软硬岩层接触带隧道不同震害形式的力学机理，评价隧道抗震与减震措施的适应性，为强震区隧道洞口的抗震设计提供理论指导与技术支撑。

Seismic damages to tunnels are likely to occur at the contact zone of soft and hard rock layers, and effective countermeasures are essential to ensure the safety of tunnels in near-fault regions. For the mechanical properties of soft and hard rocks differ sharply, the discontinuous deformation behavior of the interface between soft rock and hard rock is remarkable. The dynamic interaction between surrounding rock and tunnel is extremely complex. As a result, the damage mechanism of tunnels at this position is still unclear and a better understanding about the damage process is needed. In view of this problem, first, dynamic compression tests on intact rocks and cyclic shear tests on the soft rock - hard rock interface will be conducted, and the dynamic properties of intact rocks and cyclic shear behaviors of the rock interface will be investigated. Based on the test results, a dynamic constitutive model of the rock interface will be established. Second, the numerical simulation technique for the site seismic response at the contact region will be studied. A numerical simulation program for the dynamic characteristics of the soft rock - hard rock interface will be established. Considering the impact of rock interfaces and the travelling wave effect, an input method of spatial non-uniform ground motions will be proposed. Based on a typical tunnel, several shaking table tests and a series of numerical calculations will be conducted to study the influences of the topography, geology and ground motions on the seismic response of the tunnel. The mechanism of seismic damages to tunnels at the contact zone of soft - hard rock layers will be revealed. At last, the applicability of common strengthening and isolation measures will be evaluated, and the reasonable countermeasures will be presented to relieve the seismic damages to tunnels. This study can provide both the scientific basis and technical support for the seismic design of tunnels in near-fault regions.