地裂缝是西安市主要的环境地质灾害，而西安地铁六条线路都垂直或倾斜地穿过地裂缝，因此地裂缝的存在给西安地铁的修建造成了很大的困难。 本文以西安地铁二号线南门至南稍门区间隧道作为研究背景，首先分析了不同衬砌结构条件下，地裂缝对地铁区间隧道围岩稳定性的影响。利用有限差分软件FLAC3D对穿越地裂缝处的区间隧道的开挖过程和支护过程进行了数值模拟。通过对比分析在毛硐状态下、施加初期支护后、施加二次衬砌后的地表沉降量、拱顶位移、围岩-支护系统的应力、隧道开挖后塑性区的分布情况，发现若不采取支护措施隧道很容易坍塌，采取初期支护后，隧道的地表沉降量和拱顶位移大大降低，但是此时的位移量均不在工程要求的范围内，只有在施加二次衬砌后才能满足工程上的需要，并且这种支护结构对隧道的稳定性最为有利。其次，运用FLAC3D软件模拟分析不同开挖方法对隧道稳定性的影响，本文主要研究了全断面开挖和台阶法开挖，分析了未采取支护、只采取初期支护、同时施加初期支护和二次衬砌条件下，两种施工方法开挖所造成的地表沉降、拱顶位移及隧道塑性区的分布。通过对比发现台阶法开挖无论从控制沉降上还是控制塑性区上都优于全断面开挖。 用本课题得出的结论指导施工，为西安地铁区间隧道穿越地裂缝施工提供了一定的参考价值和实用意义。

Ground fissure is main environment disaster in Xi’an city construction. All of the lines of the Xi'an metro pass across the ground fissure vertically or obliquely, therefore the ground fissure has caused many difficulties to the construction of the Xi'an metro. On the basis of the geological situation of the south gate to Nanshao gate tunnel of the Xi’an metro, this paper analyzed the influence of the ground fissure on the country rock stability of the metro tunnel in the term of different lining structures. The excavation and support process of the metro tunnel was simulated by the finite difference software-FLAC3D in this paper. After comparing the ground surface settlement, crown displacement, the change of the stress of the country rock-support system, and the distribution of the plastic zone in the term of unsupport, initial support, and secondary lining, it confirmed that the tunnel would slump in the term of unsupported, but if the initial support is applied to the tunnel, the settlement of the ground surface and the crown displacement would reduce largely. But the displacement doesn’t satisfy the requirement of the engineering. After the secondary lining beening applied to the tunnel, the displacement satisfies the requirement of the engineering and the support system is advantageous to the stability of tunnel. Next, it studied primarily the different excavation methods adopted by the tunnel in the area of ground fissure, and analyzed the influence on the stability of the metro tunnel by using the infinite difference software-FLAC3D. This paper researched the influence of the full face excavation method and bench excavation method. It analyzed the ground surface settlement, crown displacement, the change of the stress of the country rock-support system, and the distribution of the plastic zone in the term of unsupported, initial support, and secondary lining. By comparing and analyzing, it concluded that the bench excavation is better than full face excavation. The result from this subject can instruct construction, it supplies the reference value and pratical significance to the construction of the Xi’an metro.