基于HSS—M-C先隧后站管片拆除研究

Numerical simulation study on segment removal in tunnel-first and station-later construction based on HSS and Mohr-Coulomb models

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摘要基坑施工时应严格控制好基坑支护结构的变形,变形过大时会严重影响周边建构筑物的稳定与安全。在先隧后站的地铁基坑开挖中涉及盾构管片拆除工程,合理的拆除方法能够有效控制基坑变形,可确保周边重要建构筑物安全。现以昆明先隧后站地铁基坑为依托,采用PLAXIS 3D有限元软件建立三维数值模型,基于小应变硬化土(HSS)与莫尔-库仑(M-C)模型进行有限元数值模拟,并与实际监测值进行对比分析,得出以下结论:采用“吹砂注浆回填法”拆除管片能有效减小基坑围护结构、周边建构筑物及地面沉降变形;盾构隧道范围内,土方开挖及管片拆除是引起基坑围护结构及周边建筑物变形的主要影响因素;HSS模型模拟计算的变形结果与实际工程监测结果较吻合,M-C模型模拟计算结果与监测结果差值较大(甚至相反),故在复杂环境条件下,深基坑的变形分析中采用HSS模型进行分析实用性更好。 Strict deformation control of foundation pit enclosure structures is critical in complex surrounding environments,as excessive deformation seriously affects the stability and safety of adjacent buildings and infrastructure.For tunnel-first and station-later(TFSL)metro foundation pit excavations involving shield segment removal,rational removal methods can effectively reduce the deformation of the foundation pit and ensure the safety of surrounding important buildings.No prior studies have reported the application of the sand-blowing and grouting backfill method for segment removal in TFSL foundation pits.A three-dimensional numerical model for a TFSL foundation pit in Kunming was developed using PLAXIS 3D finite element software.The numerical simulation results based on the hardening soil with small strain stiffness(HSS)and Mohr-Coulomb(M-C)models were compared with the field monitoring data.Results indicate that the proposed method for segment removal substantially reduces deformation in the enclosure structures,surrounding buildings,and ground.The critical deformation stages of the enclosure structures and surrounding buildings occur during soil excavation and segment removal within the shield tunnel range.Deformation results simulated through the HSS model closely match the monitoring data,while those from the M-C model show notable deviations or even contradictory trends,demonstrating the superior practicality of the HSS model for deformation analysis in deep foundation pits under complex conditions.

作者阮永芬马举俊许强梁龙元杨醒宇张锦春郭宇航 RUAN Yongfen;MA Jujun;XU Qiang;LIANG Longyuan;YANG Xingyu;ZHANG Jinchun;GUO Yuhang(School of Construction Engineering,Yunnan Land and Resources Vocational College,Kunming 652501,Yunnan,China;Yunnan Lida Foundation Construction Engineering Co.,Ltd.,Dali 671000,Yunnan,China;Faculty of Civil Engineering and Mechanics,Kunming University of Science and Technology,Kunming 650500,Yunnan,China;China Railway Siyuan Group Southwest Survey and Design Co.,Ltd.,Kunming 650000,Yunnan,China;Kumming Architectural Design&Research Institute Co.,Ltd.,Kunming 650228,Yunnan,China;No.5 Engineering Co.,Ltd.,China Railway 20th Bureau Group,Kunming 650000,Yunnan,China)