摘要
针对隧道工作面稳定性和破坏模式问题,从保守角度将其假定为沿隧道纵向中线剖开的二维平面应变模型,采用刚体平动运动单元上限有限元法(UBFEM-RTME)开展分析研究,绘制了土体自重作用下地层临界失稳状态对应的隧道工作面稳定系数Ncr图表和有效间断线网(近似滑移线网)破坏模式,探讨了埋深比H/D、内摩擦角φ和剪胀角ψ等参数影响规律,给出了Ncr与H/D和φ影响因素的拟合公式,进一步揭示了有效间断线数目及位置分布等网格参数对计算精度的影响程度。研究表明UBFEM-RTME数值计算配合网格更新策略并保证合理充足的网格密度,能提高Ncr上限解精度并捕获高密度有效间断线网破坏模式,其分析结果可用于评价隧道工作面稳定性、揭示极限失稳破坏形态的主要特征,为地层预加固方案制定等工作提供一定理论支撑。
The stability and collapse mechanism of tunnel faces are simplified conservatively to two-dimensional plane strain models along the longitudinal middle line of tunnel. Using the upper bound finite element method with rigid translatory moving element (UBFEM-RTME), a series of stability factors NCT and collapse mechanisms displayed with active discontinuities are deduced. The influences of dimensionless buried depth ratio H/D, internal friction angle φ and dilatancy angle ψ on the variations of Ncr and mesh-like collapse mechanisms that are identical to the form of slip lines are discussed. A fitting formula of Mr for the influence factors H/D and φ is deduced, and the effects of numbers and locations of active discontinuities are also investigated. This study illustrates that the UBFEM-RTME with combination of mesh adaptive updating strategies and reasonable and sufficient mesh density can improve the accuracy of the obtained Ncr values and the refinement of mesh-like collapse mechanism. The results reveal the main characteristics of the ultimate collapse mechanisms of tunnel faces, and they can provide theoretical supports for the stability evaluations of tunnel faces and pre-reinfdrcement scheme of soil strata.
作者
孙雁军
阳军生
罗静静
郑响凑
杨峰
SUN Yan-jun;YANG Jun-sheng;LUO Jing-jing;ZHENG Xiang-cou;YANG Feng(School of Civil Engineering,Central South University,Changsha 410075,China;Hunan Expressway Construction and Development Co.,Ltd.,Changsha 410001,China;Key Laboratory of Engineering Structure of Heavy Railway,Ministry of Education,Changsha 410075,China;Faculty of Civil Engineering and Geosciences,Delft University ofTechnology,Delft,Netherlands)
出处
《岩土工程学报》
EI
CAS
CSCD
北大核心
2019年第7期1374-1380,共7页
Chinese Journal of Geotechnical Engineering
基金
国家自然科学基金项目(51878669)
关键词
工作面稳定性
上限有限元
剪胀效应
稳定系数
破坏模式
stability of tunnel face
upper bound finite element method
dilatancy effect
stability factor
collapse mechanism
