【作者】 李俊；

【导师】 杨仲轩； 王金昌； 徐铨彪；

【作者基本信息】 浙江大学 ， 工程硕士（专业学位）， 2021， 硕士

【摘要】 城市轨道交通运营期间,近接工程数量与日俱增,使得邻近地铁车站与区间隧道结构均出现不同程度的附加内力与附加位移。尤其软土地区的隧道结构,随着服役年限的增长,出现渗漏水、衬砌裂缝等衬砌结构病害。因此完整的近接施工影响分析应包括对施工前隧道结构服役现状的确定以及在此基础上展开的施工影响分析。本文基于两阶段法的思想,将地层结构法分别与状态空间法和结构非线性分析相结合,提出新的旁侧基坑开挖影响分析方法,给运营期隧道结构的健康安全管理提供重要的指导意义。基于地层结构法建立的大尺寸模型能有效地考虑岩土工程环境的复杂性。尤其对于形状不规则基坑,三维有限元模拟过程可以较好地考虑到基坑开挖过程中的时空效应,但对结构物的考虑较为简单,隧道常被等效为刚度折减的均质圆环。隧道的荷载结构法考虑到管片接头,结构上进一步精细化,但模型中线弹性地基弹簧未能全面考虑到周边环境的变化。因此本文提出两阶段分析方法,首先确定典型区间隧道的结构服役现状,继而通过地层结构法得到侧方基坑施工作用下车站变形以及隧道结构的变形及内力响应,在此基础上考虑到管片接头以及结构非线性,将位移与内力作为结构外荷载叠加到基床模型进行第二阶段计算。本文研究内容主要如下:(1)针对基坑开挖影响区内的区间隧道进行衬砌病害检测,统计单环衬砌的最大收敛量以及病害类型及其分布,得到了衬砌病害在环向与纵向上的分布规律,并对区间隧道的服役现状进行评价,得到隧道结构的安全控制指标。(2)基于地层结构法建立车站-隧道-基坑的三维数值模型,考虑了土与结构的相互作用以及基坑开挖的时空效应,结合隧道结构安全控制指标分析旁侧基坑开挖对邻近车站与区间隧道的变形影响,得到的隧道位移及内力响应结果作为后续第二阶段分析的外荷载。(3)针对旁侧基坑开挖对邻近车站与隧道结构的影响进行多参数分析,讨论了坑隧距的变化对车站变形和浅埋隧道与深埋隧道的纵向变形影响,分析不同坑隧距与基坑开挖深度下,基坑围护结构角点对隧道纵向位移的约束效果。(4)基于开挖前隧道的最大收敛量和地层结构法得到的隧道位移与周围土压力计算结果,提出在单环衬砌基床模型上进行应力叠加和位移叠加。通过两阶段计算分析获得隧道结构的横向变形、内力响应与结构损伤响应,结果证明该方法既能兼顾复杂岩土工程环境下大尺寸建模,并满足了衬砌结构精细化分析的需要。更多还原

【Abstract】 During the operation of urban rail transit,the number of adjacent projects has been increasing day by day,which caused different degrees of additional internal force and displacement in the adjacent metro structure.Especially for the tunnel structure in soft soil area,with the increase of service life,lining structure diseases such as water leakage and lining cracks have emerged.Therefore,the complete near construction impact analysis should include the determination of the service status of tunnel structure before construction and the construction impact analysis on this basis.Based on the idea of two-stage method,this paper combines stratum structure method with state space method and structural nonlinear analysis respectively.Two new influence analysis methods of side excavation were proposed,which could provide important guidance for the health and safety management of tunnel structure during operation.The large-scale model based on the stratum structure method could effectively consider the complexity of geotechnical engineering environment.Especially for the irregular shape foundation pit,the spatial and temporal effects of foundation pit excavation were well considered.However,the consideration of the structure was relatively simple,and the tunnel was often equivalent to a homogeneous ring with reduced stiffness.The load structure analysis of the tunnel took into account the segment joint,and the structure was further refined.However,the linear elastic foundation spring of the model failed to fully consider the change of the surrounding environment.Therefore,the two-stage analysis methods were proposed in this paper.Firstly,the structure service status of typical interval tunnels was determined,and the deformation and internal force response of the adjacent metro structure under side excavation construction were obtained by stratum structure method.On this basis,considering the segment joint and structural nonlinearity,the displacement and internal force were superimposed as the external load of the structure to the foundation bed model for the second stage calculation.The research contents and conclusions of this paper are as follows :(1)According to the tunnel lining disease detection in the influence area of foundation pit excavation,the maximum convergence and structural diseases of single ring tunnel was counted.What’s more,the circumferential and longitudinal distribution of tunnel structure disease were obtained.Lastly the service status of the interval tunnel was evaluated to obtain the safety control index of the tunnel structure.(2)The three-dimensional numerical model of station-tunnel-foundation pit was established based on the stratum structure method,which considered the interaction between soil and structure and the space-time effect of foundation pit excavation.Combined with the safety control index of tunnel structure,the influence of excavation of adjacent foundation pits on the deformation of the metro structure was analyzed.The obtained tunnel displacement and internal force response results were used as the external loads for the subsequent second stage analysis.(3)Multi-parameter analysis was carried out for the influence of the excavation of the lateral foundation pit on the metro structure.The results show that the change of the distance between the pit and tunnel influences the station deformation and the longitudinal deformation of shallow and deep tunnels.What’s more,analyzed the restraint effect of the corners of the foundation pit retaining structure on the longitudinal displacement of the tunnel under different pit-tunnel distances and foundation pit excavation depths.(4)Based on the maximum convergence amount of tunnel and the tunnel displacement and the surrounding earth pressure calculation results by the stratum structure method,it was proposed to carry out stress superposition or displacement superposition on the single-ring lining bed model.The lateral deformation,internal force response and structural damage response of the tunnel structure were obtained through two-stage calculation and analysis.The results proved that the methods could not only take into account the large-scale modeling in the complex geotechnical environment,but also meet the needs of fine analysis of the lining structure.更多还原