连拱隧道不同施工阶段结构体系可靠度计算

Study on system reliability of double span tunnel during different construction stages

针对连拱隧道的不同施工阶段,根据在围岩压力作用下隧道衬砌的内力分布情况,以串、并联体系为基础,确定了连拱隧道不同施工阶段的体系失效模式。充分考虑材料性能参数、几何尺寸、围岩弹性抗力系数及荷载等的随机性影响,采用蒙特卡罗-随机有限元法对隧道衬砌截面的可靠度进行了研究,进而采用区间估计的"宽界限法"对连拱隧道不同施工阶段结构体系的可靠度进行了计算。计算结果表明,连拱隧道施工阶段单洞完成后中墙部位的体系可靠指标最小,不能满足长期使用的承载能力要求,施工中应注意中墙的安全,并尽早形成对称连拱结构。

According to the inner forces distribution of double span tunnel under the surrounding rock loading action during different construction stages, the failure mode of the tunnel lining are made by a series- parallel connection system. Then, the Monte-Carlo random FEM is adopted to calculate the reliability of tunnel lining section, with full consideration of influence of the material characteristics, geometric dimensions, elastic resistance coefficient of surrounding rock, loading, etc.; and by using the breadth border method, a range estimation method, the system reliabilities of tunnel lining during different construction stages are studied. The system reliability index of a typical tunnel case is calculated in the end. The calculated results show that the system reliability index of middle wall is smallest after the single tunnel is excavated; and it can＇t be safe when be used in long-term. When the tunnel is in construction, the safety of middle wall must be pay attention; and the double arch should be built as soon as possible.