采用数值模拟方法,分析了不同隧道开挖工法对不同围岩级别二衬合理支护时机的影响。计算结果表明:开挖工法对二衬与掌子面间的允许间距影响比较显著,而对仰拱与掌子面间距的影响很小。随着开挖断面分部的增加,开挖对围岩的扰动减小,因而可以适当延缓构筑二衬。 The numerical simulation method is used to analyze the influence of different tunnel excavation methods on the timing of reasonable support of the second lining in different surrounding rock. The calculation results show that the excavation method has a significant effect on the allowable spacing between the second liner and the face, and has little effect on the distance between the back and the face. As the part of excavation section increases, the disturbance to the surrounding rock of excavation will be reduced, so construction of the second lining can be postponed properly.