ISSN 1000-3665 CN 11-2202/P

    逆断层错动下基岩上覆土-隧道多尺度响应特征

    Multi-scale response characteristics of overlying soil-tunnel system under reverse fault dislocation

    • 摘要: 基岩断层错动在上覆土层中的传播破裂过程受多种因素控制,上覆土跨断层隧道结构在断层错动下的响应机制尚不清晰。为解决这一问题,建立了基岩断层上覆土与隧道结构的三维离散-连续耦合模型,采用离散元模拟上覆土层细观颗粒特性与变形模式,采用有限差分法计算隧道结构宏观力学响应,并通过界面耦合实现宏-细观交互传递。基于该方法,分析了基岩断层错动在上覆土层中的破裂传播过程,上覆土中隧道结构的变形受力响应,并探究了断层倾角与隧道埋深对隧道响应及失效模式的影响机制。结果表明:基岩断层错动在上覆土层中以剪切带的形式传播,隧道结构的存在将增大地层位错变形范围;隧道结构的受力变形模式为由隧道纵向受弯导致的受弯区上下盘衬砌应力反对称分布,隧道结构失效最先发生在上盘区段,体现出显著的上盘效应;在相同基岩错动量条件下,断层倾角越小,隧道结构受力越不利;隧道埋深越深,其周围土体变形范围越集中,隧道结构受力越不利。研究可为基岩断层错动作用下上覆土中隧道结构抗震设计提供科学依据。

       

      Abstract: The propagation and rupture process of bedrock fault dislocation in the overlying soil layer is controlled by many factors, which makes the response mechanism of the tunnel structure crossing the overlying soil under fault dislocation unclear. To solve this problem, a three-dimensional discrete-continuous coupling model is established, in which the discrete element is used to simulate the microscopic characteristics of the soil particles and deformation mode of the overburden layer, the finite difference method is used to calculate the macroscopic mechanical response of the tunnel structure, and the interface coupling is used to realize the interactive transfer between the above two methods. Based on the multi-scale model, the rupture propagation process of bedrock fault dislocation in the overlying soil layer, as well as the deformation response of the tunnel structure in the overlying soil are investigated. The effects of the fault dip and the depth of tunnel on the tunnel failure mode are also investigated. Results show that the bedrock fault dislocation propagates in the form of shear zone in the overburden, and the existence of tunnel structure will increase the deformation area of the soil. The deformation mode is the anti-symmetric distribution of lining stress in the upper and lower disks of the bending area caused by longitudinal bending of the tunnel, and the structural failure of the tunnel structure occurs firstly in the upper disk section, which shows the significant effect of the upper disk. Suffering the same bedrock dislocation, the tunnel structural is more likely to be damaged with a smaller fault dip. In addition, under a higher depth of tunnel, the deformation zone of the surrounding soil will be concentrated, resulting in the instability of the tunnel. The study can provide a scientific basis for the seismic design of tunnel structures in the overlying soil under the action of bedrock fault dislocation.

       

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