Abstract In this study, reliability and sensitivity analyses were employed to investigate the effects of a weak interlayer on tunnel face stability. Due to the irregular geology process and the movement of tunnelling machine, the situations of weak soils encountered during tunnel construction are complex and variable. To address this problem, this paper adopted reliability and sensitivity analysis to evaluate the face stability of a tunnel considering a weak soil layer. An active learning method which combines Kriging and Monte Carlo Simulation (AK-MCS) was used for the reliability analysis. Then, the importance of each stochastic soil property was estimated by coupling the surrogate model constructed in the AK-MCS with the global sensitivity analysis (GSA). Compared with traditional approaches, the employed technique (termed as AK-MCS-GSA) is able to provide a variety of interesting results (failure probability, model response statistics and sensitivity index) but with a greatly reduced computational time. The obtained results permitted to show that a weak soil layer over the tunnel cross-section can lead to a significant increase of failure probability. Additionally, the sensitivity indices in GSA revealed that the soil's frictional angle of the weak layer has the greatest influence on the face stability. Moreover, the impacts of varying the weak layer’s position and thickness are discussed. The critical position for the weak layer which leads to the biggest failure probability is remarked.

中文翻译：

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薄弱层对掌子面稳定性的影响——可靠性和敏感性分析

摘要 在本研究中，采用可靠性和敏感性分析来研究弱夹层对掌子面稳定性的影响。由于不规则的地质过程和掘进机的运动，隧道施工中遇到的弱土情况复杂多变。针对这一问题，本文采用可靠性和敏感性分析来评估考虑弱土层的隧道掌子面稳定性。结合克里金法和蒙特卡罗模拟（AK-MCS）的主动学习方法用于可靠性分析。然后，通过将 AK-MCS 中构建的替代模型与全局敏感性分析 (GSA) 耦合来估计每个随机土壤属性的重要性。与传统方法相比，所采用的技术（称为 AK-MCS-GSA）能够提供各种有趣的结果（故障概率、模型响应统计和灵敏度指数），但计算时间大大减少。所得结果表明，隧道横截面上的弱土层会导致失效概率显着增加。此外，GSA 中的敏感性指数表明，弱层土壤摩擦角对工作面稳定性的影响最大。此外，还讨论了改变弱层位置和厚度的影响。指出导致最大失效概率的薄弱层的关键位置。模型响应统计和灵敏度指数），但大大减少了计算时间。所得结果表明，隧道横截面上的弱土层会导致失效概率显着增加。此外，GSA 中的敏感性指数表明，弱层土壤摩擦角对工作面稳定性的影响最大。此外，还讨论了改变弱层位置和厚度的影响。指出导致最大失效概率的薄弱层的关键位置。模型响应统计和灵敏度指数），但大大减少了计算时间。所得结果表明，隧道横截面上的弱土层会导致失效概率显着增加。此外，GSA 中的敏感性指数表明，弱层土壤摩擦角对工作面稳定性的影响最大。此外，还讨论了改变弱层位置和厚度的影响。指出导致最大失效概率的薄弱层的关键位置。s 薄弱层摩擦角对工作面稳定性影响最大。此外，还讨论了改变弱层位置和厚度的影响。指出导致最大失效概率的薄弱层的关键位置。s 薄弱层摩擦角对工作面稳定性影响最大。此外，还讨论了改变弱层位置和厚度的影响。指出导致最大失效概率的薄弱层的关键位置。