摘要
目前对于浅埋大跨地铁隧道拱盖法导洞施工顺序优化的研究较少,因此以广州市轨道交通11号线华景路站—华师站区间大跨暗挖段拱盖法导洞施工为研究背景,采用三维有限差分数值方法模拟不同导洞施工顺序下的施工全过程,研究围岩和支护结构的力学特征变化规律,进而优化导洞施工顺序,并通过现场监测对数值模拟分析结果加以验证。结果表明:导洞施工顺序的不同主要影响围岩和支护结构的力学特征变化过程,中间导洞的开挖对于围岩最大主应力和支护结构内力影响显著;若采用先开挖拱顶部位导洞的施工方案则围岩中会出现拉应力,影响施工安全,并且支护结构内力也会较大;而采用先开挖拱脚部位导洞的施工方案则围岩更加稳定,支护结构更加安全;不同导洞施工顺序虽然导致施工过程中围岩位移变化产生差异,但对围岩最终变形的影响不显著;“先下后上,先边后中”的原则同样适用于拱盖法的导洞开挖,对于单跨无柱结构,非对称的单导洞开挖方案相较于对称的双导洞开挖方案能更好地控制围岩位移和应力以及减小支护结构内力。
At present,there are few studies on the optimization of the construction sequence of the shallow-buried large-span subway tunnel by arch cover method.Therefore,taking the construction of the large-span underground excavation section of Huajing Road Station-Huashi Station of Guangzhou Rail Transit Line 11 by arch cover method as an example,3D finite difference numerical method is used to simulate the whole construction process under different construction sequences of the pilot tunnel.The mechanical characteristics law of the surrounding rock and the supporting structure are studied to optimize the construction sequence of the pilot tunnel.The numerical simulation results are verified by field monitoring.The results show that the different construction sequence of the pilot tunnel mainly affects the mechanical characteristics of the surrounding rock and the supporting structure.The excavation of the middle pilot tunnel has a significant influence on the maximum principal stress of the surrounding rock and the internal force of the supporting structure;If the construction scheme of excavating the guide hole at the vault first is adopted,tensile stress will appear in the surrounding rock which affect the construction safety and the internal force of the supporting structure will be larger;That the construction scheme of excavating the guide hole at the arch foot firstly is more stable and the supporting structure is safer;Although different pilot tunnel construction sequences cause different displacement changes of surrounding rock,the influences on the final deformation of surrounding rock are not significant;The principle of 4first down and then up,first edge and then middle5 is also applicable to the excavation of the guide hole by arch cover method.Compared with the symmetrical double guide hole excavation scheme,the asymmetric single guide hole excavation scheme can better control the displacement and stress of the surrounding rock and reduce the internal force for the single-span column-free structure.
作者
高晓刚
尹学鑫
王忠钊
舒文韬
王鸿宇
Gao Xiaogang;Yin Xuexin;Wang Zhongzhao;Shu Wentao;Wang Hongyu(China Railway No.3 Engineering Group Guangdong Construction Engineering Co.,Ltd.,Guangzhou 510000,China;Key Laboratory of Transportation Tunnel Engineering,Ministry of Education,Southwest Jiaotong University,Chengdu 610000,China)
出处
《市政技术》
2023年第4期139-147,168,共10页
Journal of Municipal Technology
关键词
浅埋大跨地铁隧道
拱盖法
导洞施工
施工顺序优化
shallowly buried metro tunnel with large span
arch cover method
pilot tunnel construction
construction sequence
