摘要
针对超大断面扁平结构矿山法公路隧道洞口段偏压问题展开研究,利用数值仿真技术对所提出的反压回填加固方案进行分析,且在数值模型中考虑了双线隧道不同开挖顺序对偏压问题的影响。数值仿真结果表明:反压回填能够有效解决浅埋偏压隧道的拱顶塌落、不均匀沉降、水平变形大和不对称应力分布等问题,验证了反压回填方案的可行性。综合评价结果表明:反压回填后先开挖深埋侧隧道对围岩变形的影响更小。在此基础上,结合现场施工方案深入分析了超大断面扁平结构隧道的围岩应力分布特征,现场施工监测数据与数值模拟结果具有较高的匹配度,验证了数值模型的准确性,以及所提出优化施工方案的可行性。该研究结果可为超大断面扁平结构隧道洞口偏压段的设计和施工提供理论支撑和参考。
This paper examines the issue of asymmetrical pressure at the entrance of a super-large section flat structure mine tunnel.The study employs numerical simulations,utilizing the finite difference software FLAC3D,to analyze a proposed backfilling scheme.The simulations consider the impact of varying excavation sequences in double-line tunnels on the asymmetrical pressure problem.Consequently,numerical models were developed to examine four distinct excavation strategies:Unbackfilled with the left line excavated first,unbackfilled with the right line excavated first,backfilled with the left line excavated first,and backfilled with the right line excavated first.By analyzing the distribution of plastic zones,as well as the vertical and horizontal displacements of the tunnels under these varying excavation strategies,the feasibility of the backfilling approach was assessed and validated.The backfilling scheme effectively addresses the issue of uniform settlement of the surrounding rock under biased conditions,thereby mitigating the horizontal displacement of the tunnel vault and the horizontal convergence of the sidewall,ultimately enhancing the stability of the surrounding rock.The stress distribution within the tunnel’s surrounding rock follows the pattern of“arch foot>sidewall>arch floor>vault”with stress concentrations occurring at the arch foot and the vault being prone to tensile failure,which reflects the stress characteristics of the surrounding rock in super-large section flat structure tunnels.The implementation of a backfilling scheme mitigates issues related to loosening at the vault and asymmetrical stress distribution at the arch footings.Based on an analysis of surrounding rock deformation,the concept of secondary deformation is introduced,allowing for a comparative assessment of the secondary impacts of various excavation sequences on the tunnel.The findings indicate that,for the tunnels under study,the optimal excavation sequence postbackfilling is to first excavate the left line followed by the right line.Conversely,the optimal sequence prior to backfilling involves first excavating the right line and then the left line.The results of the final comprehensive evaluation indicate that initiating excavation on the deeply buried side of the tunnel post-backfilling significantly reduces the deformation of the surrounding rock.Based on numerical simulation outcomes,appropriate reinforcement measures are recommended for practical construction applications.Furthermore,an indepth analysis of the stress distribution characteristics of the surrounding rocks and supporting structures in super-large section flat structure tunnels is conducted in conjunction with the on-site construction plan.The monitoring data closely align with the numerical simulation results regarding the deformation observed around the periphery of the tunnel’s cross-section.This congruence confirms the accuracy of the numerical model developed in this study and underscores the viability of the proposed optimized construction scheme.The findings presented herein offer theoretical support and serve as a data reference for the design and construction of the entrance bias section in super-large section flat structure tunnels.
作者
孟陈祥
林厚权
李响
陈国政
刘建坤
MENG Chenxiang;LIN Houquan;LI Xiang;CHEN Guozheng;LIU Jiankun(Shanghai Tunnel Engineering Co.,Ltd.,Shanghai 200032,China;School of Civil Engineering,Sun Yat-Sen University,Zhuhai 519000,Guangdong,China)
出处
《黄金科学技术》
北大核心
2025年第1期159-172,共14页
Gold Science and Technology
基金
上海隧道工程有限公司专项研究科研项目“软弱地层超大断面扁平结构矿山法隧道施工关键技术研究”(编号:2022-sk-19)资助。
关键词
超大断面
扁平结构
双线隧道
洞口偏压
软弱围岩
数值模拟
super-large section
flat structure
double-line tunnel
entrance bias
weak surrounding rock
numerical simulation
