为了解决隧道洞门结构紧贴路基桩时条带理论进行稳定性验算结果过于保守的问题，以某单线铁路隧道明洞门设计为例，利用ANSYS软件对该隧道明洞门在主动土压力作用下进行静力分析，提出了一种有别于条带理论的整体稳定性分析方法。主要研究内容和结论如下： 1）当洞门结构外有桩体对洞门变形进行约束时，传统的条带检算理论过于保守，将整个力系一并考虑进行整体稳定性分析，在满足相同安全系数的基础上，可以降低圬工和施工难度，提高设计的技术经济合理性； 2）当洞门结构紧贴路基桩，且桩洞净距小于3倍桩径时，桩对洞门稳定性的提高作用明显，当桩洞净距扩大时，稳定安全系数减小，当净距为3~4倍桩径时，安全系数不满足规范要求。

When the stability of an opencut tunnel portal close to the antislide piles of the subgrade is calculated based on the band theory, the calculation result is often too conservative. In the paper, static analysis is made on an opencut portal of a singletrack railway tunnel under active earth pressure by means of ANSYS program, and a new stability analysis method, which is different from the conventional band theory, is proposed. The main research contents and conclusions are as follows: 1) If, outside of the tunnel portal structure, there are piles which constrain the deformation of the tunnel portal, the result of the conventional band theory is too conservative; in such case, integral stability analysis can be made based on the whole force system, which may result in the reduction of the amount and construction difficulty of masonry works and the improvement of the economic rationality of the design, while the same safety coefficient is satisfied; 2) When the tunnel portal structure is close to the piles and the clear spacing between the piles and the tunnel portal is less than 3 times the pile diameter, the piles have obvious effect in improving the stability of the tunnel portal; as the clear spacing between the piles and the tunnel portal increases, the safety coefficient reduces; when the clear spacing between the piles and the tunnel portal is 3～4 times the pile diameter, the safety coefficient cannot meet the requirements of relevant codes.