富水地层隧道初期支护可靠度研究

Research on Reliability of Tunnel Primary Support in Water-Rich Stratum

以富水地层条件下的康家楼隧道1号斜井为依托,采用荷载结构模型进行数值模拟,确定初期支护最不利位置。以初期支护主要影响因素水压、初支厚度为随机变量,拟合确定支护安全性极限方程,使用基于最优化原理的蒙特卡罗法对最不利位置可靠度进行试算。研究表明支护轴力、弯矩随水压是线性变化的,与初支厚度是非线性关系;墙脚的安全度是最低的,拱顶、边墙次之,且它们的可靠度指标均小于规范要求,因此二衬应尽量早上,以防引起塌方;最危险点在墙脚,因此必须加强设计参数来减少墙脚失效概率。

By relying on the No.1 inclined shaft tunnel of Kangjialou Tunnel under the conditions of water-rich strata,a load-structure model for numerical simulation is used to determine the most unfavo rable positions of primary support.With the main factors of primary support which contain water pressure and the thickness of primary support as the random variable,they are fitted to determine the limit equation of supporting security and the reliability of the most unfavorable positions are calculated by Monte-Carlo method based on the principle of optimality.Studies show that support axial force and bending moment are linear with pressure and are non-linear with the thickness of primary support.Foot of a wall of security is the lowest,followed by vault and wall,whose reliability index is less than specifications,so that secondary lining should be built as soon as possible to prevent landslides;because the foot of a wall is the most dangerous,it must strengthen design parameters to reduce its probability of failure.