大跨度连拱隧道支护体系的现场监测及数值模拟

文章对某大跨度连拱隧道施工全过程进行现场监测,在监测结果的基础上,结合数值模拟进行分析与研究,得出大跨度连拱隧道在开挖过程中的力学特征.结果表明：（1）上台阶开挖对钢支撑受力的空间效应明显,是隧道支护监测的控制点；（2）钢支撑和二衬前期内力增加较快,随后逐渐趋于稳定,二衬内力大约1年内趋于稳定；（3）中墙侧衬砌最易受到临洞施工影响,衬砌受力也最复杂；（4）对大跨度连拱隧道进行数值模拟一定程度上能得到开挖过程中的力学特征,但是由于隧道跨度大,地质条件复杂,开挖步骤多,数值模拟结果与实际有较多不同.

In-situ Monitoring and Numerical Simulation on Supporting System of Large-span Tunnel with Multi-arch

In this paper, the construction of a large-span tunnel with multi-arch is monitored, on the basis of monitoring data, the mechanical characteristics during excavation process is concluded combined with numerical simulation analysis. Results show that： （1） The changes of steel support internal force caused by cavern upper bench excavation is maximum, the upper bench excavation influences steel support stress obviously which is the control point in tunnel support monitoring. （2） The internal force of steel support and secondary lining increases fast in earlier stage, then became stable in about a year. （3） the side-lining of the middle-wall is influenced by adjacent cavern construction easily, and the lining force is the most complicated. （4）The numerical simulation of the large-span tunnel with multi-arch can get mechanical features of excavation process in some degree, but there are many different between simulation and practice because of large span, complex geological conditions, excavation procedure, etc.