复杂地质条件下隧道支护体时效可靠性分析

Analysis of aging reliability of tunnel support system under complicated geological condition

由于隧道围岩具有蠕变特性,导致隧道结构的可靠性与稳定性有着显著的时效特性.很多隧道塌方事故并不是在当前掌子面发生的,而是在隧道开挖支护完成一段时间后才发生,但目前对于此类事故的研究,即隧道围岩及支护结构的时效可靠性的研究很少.将支护体系的时效破坏概率定义为支护体的实际位移值超过极限位移的概率.根据相关规范以及法国学者Louis提出的最大容许位移约为埋深的1‰的理论,可以计算得到隧道断面上不同位置处不同方向的极限位移,即位移阀值.利用ABAQUS有限元软件对张石高速岳家沟隧道工程RK75+880断面进行建模分析,选择时效硬化蠕变本构模型,作出断面上各个观测点处的支护体位移时程曲线.确定各个观测点处的极限位移,进而计算各个观测点的时效破坏概率,分析隧道断面的时效可靠性与稳定性.

Due to the creep characteristics of a tunnel, the reliability and stability of the tunnel structure have significant aging characteristics. Many tunnel collapse accidents do not occur in the current face, but after the tunnel excavation support is completed for some time. However, there is little research on the aging reliability of tunnel surrounding rock and supporting structure, and the probability of aging failure of the support system is defined as the actual displacement value of the support body exceeding the limit displacement. According to the relevant norms and French scholar M. Louis, the maximum allowable displacement is about 1‰ of the buried depth, the limit displacement, ie, the displacement threshold, can be calculated in differeut directions at different positions on the tunnel section. Using ABAQUS finite element, the model is established on the RK75 ＋ 880 section of the Zhangji high-speed Yuejiagou tunnel project, and the aging creep creep constitutive model is selected to make the displacement curve of the support body at each observation point in the section to make clear the limit of each observation point, and then calculate the aging failure probability of each observation point, and analyze the aging reliability and stability of the tunnel section.