偏压浅埋连拱隧道施工过程的三维数值模拟

针对一座浅埋偏压条件下的双连拱隧道，分别按三导洞先墙后拱法和中导洞法对其施工过程进行了三维弹塑性有限元模拟分析。计算结果揭示了该条件下双连拱隧道衬砌结构的受力和变形以及围岩的塑性区分布都具有明显的非对称特性，衬砌内侧的拱部和内外侧仰拱承受了较大的拉应力而成为结构的薄弱环节，中隔墙因在不对称水平推力作用下发生偏转成为影响衬砌结构稳定的关键因素，并在此基础上对提高结构的稳定性提出了建议。

3D Numerical Simulation for Construction of Shallow Double Arched Tunnel under Bias Pressure

As a new structural style of road tunnel, a lot of double arched tunnels have been constructed currently. Owing to its sophisticated structure, large span and excavation method, some tunnels have cracks on its lining. For a shallow double arched tunnel under bias pressure, a 3D elastic-plastic finite element analysis was conducted to simulate the construction by mid heading method and triple heading method separately. Result indicates that the stress and deformation of tunnel lining and the plastic zone distribution of surrounding rock mass obviously are asymmetric. The inner side of arch and the invert of both sides are tunnel lining's weak spots for its excessive tension stress, and the interval wall is a critical factor for the stability of lining under unbalanced horizontal thrust. Some advices are presented on the basis of simulation for improving the stability of tunnel lining.