隧道开挖过程中掌子面空间变形特征试验模拟与分析  

Test simulation and analysis of excavation face spatial deformation characteristicsduring tunnel construction

作　　者：李清川 路兆武 LI Qingchuan;LU Zhaowu(Ji’nan Jinke Junyao Real Estate Development Co.,Ltd,Ji’nan,Shandong 250100,China;Ji’nan Xindu Real Estate Co.,Ltd.,Ji’nan,Shandong 250100,China)

机构地区：[1]济南金科骏耀房地产开发有限公司,济南250100 [2]济南鑫都置业有限公司,济南250100

出　　处：《地质装备》2023年第4期32-39,共8页Equipment for Geotechnical Engineering

摘　　要：隧道施工过程中的监控测量是指导施工顺序、确保施工安全的重要手段。目前,隧道施工现场多采用以拱顶沉降和水平收敛为主的二维监测指标,难以获取开挖掘进过程中掌子面核心土的动态变形量。为了探究隧道施工过程中开挖面的空间变形特征,以两水隧道为试验原型,基于相似准则,开展了大比尺地质力学模型试验,获取了掌子面及前方围岩位移和应力随施工进程的变化规律,建立了掌子面与围岩变形释放率预测模型。结果表明,采用50 mm进尺的全断面法开挖,拱顶沉降变形和应力释放量均大于拱腰处径向变形,但最终都收敛,由FLAC 3D数值模拟对比分析,验证了全断面开挖在千枚岩地质环境中的可行性;掌子面变形释放率拐点先于同一断面围岩径向变形且发生在开挖到目标断面之前,应将掌子面变形作为隧道施工的关键监测指标,综合考虑掌子面随开挖时空变化的变形特征。试验真实呈现出了施工过程中隧道变形特征,揭示了掌子面及其前方围岩随开挖进尺的变形机制,试验结论对支护手段和支护时机选择提供了科学参考。Monitoring and measurement during tunnel construction is an important means to guide the construction sequence and ensure construction safety.At present,two-dimensional monitoring indicators mainly focused on arch settlement and horizontal convergence are commonly used in tunnel construction sites,making it difficult to obtain the dynamic deformation of the core soil of the tunnel face during excavation.In order to explore the spatial deformation characteristics of excavation face during tunnel construction,a large-scale geo-mechanical model experiment was conducted using the Liangshui tunnel as the experimental prototype based on similarity criteria,the variation patterns of displacement and stress of the tunnel face and surrounding rock ahead with the construction process was obtained,and a prediction model for the deformation release rate of the excavation face and surrounding rock was established.The results show that the settlement deformation and stress release of the arch crown are greater than the radial deformation of the arch waist when the full-face method of 50 mm footage is used in excavation,but they converge at last.The comparative analysis of FLAC 3D numerical simulation verifies the feasibility of full-face excavation in the geological environment of Phyllite;The inflection point of the deformation release rate at tunnel face is prior to the radial deformation of the surrounding rock in the same section and occurs before excavation to the target section.Therefore,the deformation of tunnel face should be considered as a key monitoring indicator for tunnel construction,taking into account the deformation characteristics of tunnel face as it changes with excavation time and space.The experiment truly presented the tunnel deformation characteristics during construction process,revealing the deformation mechanism of tunnel face and surrounding rock ahead as the excavation progresses.The experimental conclusions provide a scientific reference for the selection of support measures and supporting time.

关 键 词：地质力学模型试验 隧道工程 掌子面 变形释放率 

分 类 号：TU43[建筑科学—岩土工程]