二向不等围压条件下考虑软化及剪胀的圆形隧洞弹塑性解

 基于弹塑性软化模型和非关联流动法则，考虑侧压力系数、极轴夹角和不同工况主应力对应关系，同时结合屈服后岩体的软化和剪胀特性，推导出圆形隧洞在二向不等压受力条件下洞周围岩的弹塑性应力、位移和塑性半径的解析解。实例分析表明，侧压力系数和主应力对应关系决定洞周塑性区的分布形状。剪胀对洞周位移的影响远大于对塑性半径的影响；剪胀程度的变化对洞周变形的影响随着围岩软化性质的增强而增大。在以洞周变形为控制的工程项目中，围岩软化和剪胀特性的影响不能忽视。

ANALYTICAL SOLUTIONS OF CIRCULAR TUNNEL UNDER TWO-DIMENSION UNEQUAL PRESSURE CONSIDERING DILATANCY AND SOFTENING

Base on the elastoplastic softening model and non-associated flow rule，the lateral pressure coefficient，the included angle with the polar axis and principal stress corresponding relations under different engineering conditions are considered. Combine with the strain softening and dilatancy characteristic of rock after it comes into the yield stage，the analytical solutions of elastoplastic stress，displacement and plastic radius of the circular tunnel are deduced. The result of computation example shows that the lateral pressure coefficient and principal stress corresponding relations decide the distributing shape of plastic zone nearby the tunnel. Dilatancy has a much more important influence on the rock displacement nearby the tunnel than on the plastic radius. The influence of dilatancy extent to the deformation nearby the tunnel becomes larger when the strain softening characteristic of surrounding rock increases. In the project which is controlled by the displacement nearby the tunnel，the influence of strain softening and dilatancy can not be ignored.