中文摘要：

基于修正芬纳公式建立了围岩稳定性评判新方法，该方法基于轴对称模型建立径向位移解析表达式。轴对称的基本假定就是圆形洞室，静水压力和均匀初始应力场，各向同性和均匀围岩条件。通过系统分析轴对称假定条件的偏差范围对围岩稳定性判断方法的适用范围进行研究。基于经典的遵循莫尔一库仑屈服准则理想线弹埋性围岩中的洞室开挖问题，分析了各项异性和非均匀性的初始应力场及城门洞型洞室对洞壁变形的影响。研究结果对围岩稳定性评判方法的合理使用范围、精度与轴对称围岩条件提出了量化评价范围。

英文摘要：

The stability criterion for tunnels is established based on modified Fenner formula. This criterion expresses the relationship between the support pressure of a tunnel and the radial displacement of its boundary using a rotationally symmetric model. The assumptions underlying rotational symmetry are a circular tunnel, a hydrostatic and uniform initial stress field, an isotropic and homogeneous ground and uniformly distributed support pressure. The applicability limits of the stability criterion for tunnels are sounded out by systematically investigating the effect of deviations from some of the important assumptions. The classical problem of tunnel excavation in a linearly elastic, perfectly plastic ground obeying the Mohr-Coulomb yield criterion is studied, and the effects of anisotropy and non-uniformity of the initial stress field and a non-circular tunnel geometry are analyzed. The results show that the stability criterion provides a reasonably accurate approximation of allowable convergence for different ground conditions that violate the rotational symmetry.