为了解决隧道工程渗水问题，基于某隧道工程，采用MIDAS-GEN对其二次衬砌早期模筑混凝土进行非稳定温度应力场以及周围约束进行研究。研究结果表明: 约束可以改变隧道的早期拉应力场的分布,具有外围约束的隧道二次衬砌的拉应力为隧道厚度中间最大，无约束隧道的拉应力为外部最大,约束可以减小隧道外部区域的拉应力，使得远离约束区域的拉应力变大，而无约束隧道的拉应力分布与之相反。根据温度应力分布特点，建议在设计方面适当增大二次衬砌中间与外侧的配筋，在施工方面减小初期支护与二次砌衬之间约束等。

In order to solve the water leaking problem in tunnel, the unsteady thermal stress field simulation and effect of restraint conditions on early concrete of tunnel secondary lining are studied by software MIDASGEN. The study results show that: 1) The distribution of early thermal stress of the tunnel can be changed by restraint conditions. 2) The maximum tension stress filed locates in middle of tunnel secondary lining with outer restraint force; while the maximum tension stress filed locates out of tunnel secondary lining without restraint. 3) The tension stress of outer region of tunnel can be reduced by restraint; the tension stress of region away from restrained area largens; while the tension stress distribution of tunnel without restraint is opposite to that of tunnel with restraint. According to the characteristics of thermal stress distribution, the reinforcement in the middle and outer of secondary lining should be strengthened moderately in design procedure, and the restraint between primary support and secondary lining should be reduced to avoid cracks.