摘要
盾构施工下穿既有运营隧道,易导致既有线路变形过大,给地铁列车运营安全带来安全隐患。考虑盾构机与土体相互作用、衬砌‑注浆层‑土体相互作用,以及同步注浆硬化过程和压力消散等关键因素,发展了盾构施工全过程数值模拟方法。结合实际工程建立盾构下穿既有隧道三维有限元数值模型,获得了盾构下穿过程中既有隧道结构变形、内力响应、围岩压力,及其周围地层应力的发展变化规律,揭示了既有隧道的变形机理。结果表明:既有隧道在纵向上发生挠曲和扭转变形,挠曲变形呈现为中部沉降两端隆起的“V”形变形,断面扭转变形呈中间大两端小的分布形式,且随盾构掘进先逆时针扭转后顺时针扭转;对于隧道横断面,在x=-0.8D~0.8D隧道断面呈现侧向压扁、竖向伸长的变形模式,在x=±0.8D之外隧道断面呈现侧向伸长、竖向压扁的变形模式,x=-0.8D~0.8D隧道断面变形由盾构开挖引起的土体卸载引起,x=±0.8D之外的隧道断面变形由中间区域隧道断面扭转和沉降变形的传递导致。
Shield tunneling under-crossing existing operational tunnels can easily cause excessive deformation of existing lines,posing safety risks to subway train operations.By considering the key factors such as shield-soil interaction,lining-grouting layer-soil interaction,as well as synchronous grout hardening process and pressure dissipation,we developed a numerical simulation method for the entire shield construction process.Based on an actual project,a 3D finite element numerical model of shield tunneling underneath existing tunnels was established.The evolutionary patterns of structural deformation,internal force response,surrounding rock pressure and adjacent stratum stresses during shield undercrossing were obtained,revealing the deformation mechanism of existing tunnels.The results showed that the existing tunnel underwent both flexural and torsional deformations longitudinally.The flexural deformation exhibited a V-shaped pattern with middle-section settlement and end-section uplift.Sectional torsional deformation showed greater magnitude in the middle sections than at the ends,initially twisting counterclockwise then clockwise during shield advancement.For tunnel cross-sections,within the range of x=−0.8D to 0.8D,sections demonstrated lateral flattening and vertical elongation deformation patterns.Beyond x=±0.8D,sections exhibited lateral elongation and vertical flattening deformation patterns.Deformations within the range of x=−0.8D to 0.8D resulted from soil unloading induced by shield excavation.Deformations beyond x=±0.8D were caused by transmission of torsional and settlement deformations from central sections.
作者
路德春
宋涛
林庆涛
孟旭
杜修力
LU Dechun;SONG Tao;LIN Qingtao;MENG Xu;DU Xiuli(Institute of Geotechnical and Underground Engineering,Beijing University of Technology,Beijing 100124,China;Key Laboratory of Urban Security and Disaster Engineering of Ministry of Education,Beijing University of Technology,Beijing 100124,China)
出处
《防灾减灾工程学报》
北大核心
2025年第3期485-500,共16页
Journal of Disaster Prevention and Mitigation Engineering
基金
国家重点研发计划课题(2022YFC3800901)
国家自然科学基金项目(52025084,52208396)资助。
关键词
盾构
下穿施工
既有隧道
变形机理
数值模拟
shield
under-crossing construction
existing tunnels
deformation mechanism
numerical simulation
