There are few researches on the dynamic variation of the stress in the rock mass surrounding the tunnel while excavation face advancing. Three general in-situ stress case is supposed. The FLAC3D numerical simulation software is utilized. The dynamic variation of the magnitude of surrounding rock stress while tunnel face advancing is detailed studied. Conclusions can be drawn as follows: the redistribution of the stress have some connection with the characteristic of the in-situ geostress, the rule of stress variation will be different in the different in-situ stress combination, the extension of the stress variation is equal to the diameter of the excavation almost. The extension is import to the temporary supporting and other measures selecting, the maximum in-situ stress parallel to the axis of the excavation is the most favorable to the stability of the excavation. The investigation can provide an effective way for the design of the support and the selection of the support design opportunity.%洞室围岩中主应力随掌子面推进过程动态发展变化的研究较为少见.假定了三种较为常见的初始应力场分布特征,利用FLAC3D数值模拟软件,研究分析了圆形洞室洞壁围岩应力随掌子面推进过程的变化特征.研究结果表明:围岩二次应力场中主应力变化发展规律与初始地应力场相关.不同组合下主应力表现不同变化特征.掌子面推进过程中主应力主要于一倍洞径范围内动态变化,这一范围亦为洞室临时支护及其他工程措施的关键部位.洞轴与最大初始主应力平行情况最有利于洞室稳定.研究结果可为地下工程支护设计及支护等措施施加时机选择提供一定的参考.
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