浅埋圆形隧道开挖面稳定的可靠度分析

摘要

开挖面支护压力是影响隧道开挖面稳定的重要施工因素,也是进行隧道开挖稳定性可靠度分析的关键.采用FLAC3D软件计算开挖面的最小极限支护压力,结合响应面法计算浅埋圆形隧道开挖面稳定的可靠度指标β,将土体粘聚力和内摩擦角作为随机变量,考虑土体粘聚力和内摩擦角之间的相关性.分析结果表明,不考虑参数相关性计算得到的可靠性指标偏于保守.通过计算验算点处的极限支护压力与原支护压力比较,证明响应面法在结合FLAC3D计算开挖面稳定的可靠度方面是足够准确的.%Support pressure is a significant factor which influences on stability of excavation face in a shallow circular tunnel driven by a pressurized shield, which is also a key point in reliability analysis. FLAC3D simulation and response surface methodology is utilized for the reliability index β for ultimate state Both soil shear strength parameters are considered as random variables as the ultimate state studying and also taking into account the statistical correlation between cohesion and internal friction angle Finally, the assumption of uncorrelated variables was found conservative in comparison to the assumption of negatively correlated variables.