中文摘要：

介绍劣化损伤本构模型在FLAC^3D中的二次开发流程以及本构模型中软弱围岩力学参数的选取原则。然后利用FLAC^3D劣化损伤本构模型对高速铁路客运专线双线深埋隧道（Ⅳ、Ⅴ级别围岩）损伤破坏机理进行数值模拟研究，分析围岩应力场特征从而确定压力拱边界，在此基础上说明深埋隧道围岩受力分区特点；接着对埋深、侧压力系数、围岩级别对受力分区的影响进行数值模拟研究。研究结果表明：FLAC^3D劣化损伤模型可以描述深埋隧道开挖损伤区域的损伤程度，揭示深埋隧道破坏机理即深埋洞室围岩稳定性丧失的区域集中在沿最小主应力方向的“楔形”区内；深埋隧道开挖后受力分区：由隧道洞壁往外依次为劣化损伤严重区一压力拱拱体一原岩应力区；埋深、侧压力系数、围岩级别对隧道围岩受力分区范围有很大的影响。

英文摘要：

The user developed flow-chart of the degradation damage constitutive model in FLAC3D and the selection of mechanical parameters for soft-weak surrounding rock were introduced, and numerical simulations were studied for the damage and failure mechanism of a double-track high speed railway deep tunnel in rock of class IV and V according to the railway tunnel code of China. The stress in rock mass was analyzed so as to define the pressure arch boundary, and the influences on the stress distribution zone by factors like tunnel depth, the lateral pressure coefficient, the level of the surrounding rock, etc. , were studied through numerical simulations. The results indicate：（ 1 ）The FLAC^3D degradation damage constitutive model can be used to describe the extent and depth of the excavation damage zone, which reveals that the unstable region of the surrounding rocks is situated at the shearing wedge along the minimum principal stress; （2） After excavating a deep tunnel, excavation damage zone, pressure arch, and original stress zone exist in sequence outside the tunnel wall. （3） Tunnel depth, the lateral pressure coefficient and the class of the surrounding rock greatly influence the scope of the stress distributions.