Stability analysis of tunnel heading in clay with nonstationary random fields of undrained shear strength不排水抗剪强度非平稳随机场下的黏土隧道掘进稳定性分析
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Tanapalungkorn W, Yodsomjai W, Keawsawasvong S, Nguyen TS, Chim-Oye W, Likitlersuang S, 2024. Stability analysis of tunnel heading in clay with nonstationary random fields of undrained shear strength. Probabilistic Engineering Mechanics, 78: 103692.DOI: 10.1016/j.probengmech.2024.103692
黏土隧道掘进稳定性问题是岩土工程中的重大挑战。具体地，当考虑土壤空间变异性时，稳定性因子可能受地理随机场影响。本文研究了随机场对不排水黏土隧道掘进概率分析的影响。该研究假设，由于强度梯度因子，黏土不排水抗剪强度随深度线性增加。采用随机自适应有限元极限分析来计算隧道掘进的稳定系数。使用蒙特卡罗技术模拟不同垂直相关长度的非平稳随机场。稳定性分析考虑了几何参数 (即覆盖深度比) 和不排水抗剪强度参数 (即强度梯度、变异系数和垂直相关长度) 的非平稳随机场。随机自适应有限元极限分析下的隧道掌子面稳定性结果也可用来评估确定性安全指标实际变化下的设计失效概率。对于概率失效分析，由不同垂直相关长度引起的失效机制可能影响设计失效概率。在隧道掘进项目设计阶段，本研究结果可能会引起隧道工程从业者的极大兴趣。关键词: 随机场, 概率分析, 极限分析, 稳定性, 隧道The stability problem of a tunnel heading in clay remains a significant challenge in geotechnical engineering. Specifically, when considering the spatial variability of the soil, the stability factor may be influenced by geographically random fields. This study investigates the effect of random fields on a probabilistic analysis of a tunnel heading in undrained clay. The study assumes that the undrained shear strength of the clay increases linearly with depth due to a strength gradient factor. The random adaptive finite element limit analysis is employed to calculate the stability numbers for tunnel headings. Nonstationary random fields with varying vertical correlation lengths are simulated using Monte Carlo simulation technique. The stability analysis takes into account geometry parameters (i.e., cover depth ratio) and nonstationary random field of undrained shear strength parameters. (i.e., strength gradient, coefficient of variation, and vertical correlation length). The results of tunnel face stability using random adaptive finite element limit analysis have also been utilised to assess the probability of design failure over a practical range of deterministic factors of safety. In the context of probabilistic failure analysis, the failure mechanism resulting from varying vertical correlation lengths could influence the probability of design failure. The findings of this study can be of significant interest to tunnel engineering practitioners during the design phase of tunnel heading projects.Keywords: Random field; Probabilistic analysis; Limit analysis; Stability; Tunnelling.Fig. 1. Problem definition of heading tunnel
Fig. 2. A numerical model in OptumG2
图 3: 覆土深度比为 1 时掘进隧道的确定性分析Fig. 3. Deterministic analysis of heading tunnel for C/D = 1
图 4: 覆土深度比与强度梯度比均为 1 时的不排水抗剪强度分布与所提随机自适应有限元极限分析网格划分示例Fig. 4. An example of distribution of s_u and detailed mesh arrangement of proposed RAFELA for C/D = 1.0, ρH/μ_su0 = 1.0
图 5: 不同归一化垂直相关长度的不排水抗剪强度分布Fig. 5. Distribution of undrained shear strength with different normalised vertical correlation length (Θ_Y)
Fig. 6. Comparison the collapse and blowout tunnel with previous studies
图 7: 覆土深度比为 1 时稳定系数均值随垂直相关长度的变化Fig. 7. Variation of μN_ran with different Θ_Y for C/D = 1.0
图 8: 覆土深度比与强度梯度比均为 1 时垂直相关长度对失效概率的影响: (a) 不排水抗剪强度变异系数 25%; (b) 不排水抗剪强度变异系数 60%Fig. 8. Effect of Θ_Y on the probability of failure for C/D = 1.0, ρH/μ_su0 = 1.0: (a) COV_su = 25%; (b) COV_su = 60%
图 9: 覆土深度比与强度梯度比均为 1 且不排水抗剪强度变异系数 60% 时的概率密度函数与概率分布函数Fig. 9. PDF and CDF for C/D = 1.0, ρH/μ_su0 = 1.0 and COV_su = 60%
图 10: 覆土深度比与强度梯度比均为 1 时的剪切耗散分布Fig. 10. Distributions of shear dissipation for C/D = 1.0 and ρH/μ_su0 = 1.0
图 11: 归一化垂直相关长度为 1 时稳定系数均值随强度梯度比的变化Fig. 11. Variation of μN_ran with different ρH/μ_su0 for Θ_Y = 1.0
图 12: 归一化垂直相关长度为 1 时稳定系数均值随覆土深度比的变化Fig. 12. Variation of μN_ran with different C/D, and Θ_Y = 1.00
图 13: 覆土深度比与归一化垂直相关长度均为 1 时的失效概率影响: (a) 不排水抗剪强度变异系数 25%; (b) 不排水抗剪强度变异系数 60%Fig. 13. Effect of probability of failure for C/D = 1.0, Θ_Y = 1.00: (a) COV_su = 25%; (b) COV_su = 60%
作者信息 | Authors
Weeradetch Tanapalungkorn泰国朱拉隆功大学 (Chulalongkorn University) 工学院
泰国法政大学 (Thammasat University) 法政工学院
泰国法政大学 (Thammasat University) 法政工学院
泰国朱拉隆功大学 (Chulalongkorn University) 工学院
泰国法政大学 (Thammasat University) 法政工学院
Suched Likitlersuang, 通讯作者 (Corresp.)泰国朱拉隆功大学 (Chulalongkorn University) 工学院Email: fceslk@eng.chula.ac.th
律梦泽 M.Z. Lyu | 编辑 (Ed)
P.D. Spanos | 审校 (Rev)
陈建兵 J.B. Chen | 审校 (Rev)
彭勇波 Y.B. Peng | 审校 (Rev)
