页岩等具有层状构造的沉积岩在我国寒区铁路工程中广泛分布。此类岩体不仅力学性质具有显著的各向异性特征，寒区特殊的赋存环境亦导致其在长期冻融作用下损伤劣化严重。在此类岩体中开挖隧道极易引起围岩的非对称破坏，给川藏铁路等寒区工程建设带来极大挑战。本项目拟制备不同冻融劣化程度的页岩试样，开展室内常规加载和卸荷力学试验，研究页岩的应力路径响应及冻融劣化程度对页岩各向异性力学特征的影响。采用电镜扫描和声发射等手段，结合数字图像及矩张量方法研究冻融劣化后各向异性页岩的卸荷损伤机理。基于对冻融劣化页岩各向异性力学性质及损伤机理的深入剖析，采用细观力学均匀化方法，推导冻融各向异性页岩损伤演化方程，在不可逆热力学框架下建立考虑冻融损伤作用的岩体各向异性力学模型。研究成果可为川藏铁路为代表的寒区各向异性岩质隧道精细设计、安全施工及可靠运维提供技术支持。

Sedimentary rocks with layered structure such as shale are widely distributed in the railway engineering in cold regions of China. This type of rock mass not only has significant anisotropy in mechanical properties, but the special occurrence environment in cold regions also leads to serious damage and deterioration under long-term freeze-thaw action. Excavation of tunnels in this type of rock mass can easily cause asymmetrical destruction of surrounding rocks, which poses great challenges to the construction of Sichuan-Tibet Railway and other cold region projects. This project intends to prepare shale specimens with different degrees of damage and deterioration, carry out conventional loading and unloading mechanical tests to study the influence of stress path response and freeze-thaw deterioration on the anisotropic mechanical characteristics of shale. Scanning electron microscope, acoustic emission and other methods, combined with digital images and moment tensor methods, are used to study the unloading damage mechanism of anisotropic shale after freeze-thaw degradation. Based on the in-depth analysis of the mechanical properties and damage mechanism of the freeze-thaw degradation anisotropic shale, the micromechanical homogenization method is used to establish an anisotropic mechanical model of rock mass considering the role of freeze-thaw damage under the irreversible thermodynamics framework. The research results can provide technical support for the precise design, safe construction and reliable operation and maintenance of anisotropic rock tunnels in the cold region represented by the Sichuan-Tibet railway.