【作者】 王芳；

【导师】 贺少辉； 刘军；

【作者基本信息】 北京交通大学 ， 地下工程， 2013， 博士

【摘要】 北京地铁14号线将台站在大直径盾构隧道先行贯通的基础上,采用PBA法扩挖形成车站主体结构,这种工法可以有效地解决盾构区间施工与车站施工的矛盾,提高车站站位选择的灵活性。这是一种新型工法,无工程先例可以借鉴。本文对其施工风险、风险控制技术、结构受力转换规律、以及施工过程对环境的影响等方面进行了深入的研究。(1)从工程经济、技术等方面对扩挖车站施工方案进行比选,并结合数值方法得出最佳方案。在此基础上,对PBA法扩挖大直径盾构隧道修建地铁车站的过程进行风险源辨识,提出相应的风险控制技术措施。(2)由于扩挖车站主体结构大部分处于盾构施工扰动区,为合理地对扩挖过程进行施工力学分析,对盾构隧道施工过程地表沉降监测数据进行了地层力学参数反分析,得出现场地层力学参数,结果表明参数符合工程实际,这对后续扩挖施工过程的研究具有理论和实践的双重作用。(3)采用三维非连续接触模型精确地模拟扩挖施工过程,对车站主体结构的风险源,即四类关键节点——管片接头、K管片分块连接、纵梁与管片连接处、初支及钢支撑与管片连接处进行了受力分析。结果表明,扩挖过程中地层荷载和结构受力通过连接节点传递,结构基本处于稳定状态。在明确结构关键节点受力和变形、关键工序受力转换规律和对结构整体影响的基础上,从工程技术方面对扩挖施工过程进行风险控制,这些技术措施将可保证车站施工过程的安全与稳定。(4)详细研究了车站主体结构扩挖施工对邻近地下管线的影响规律,提出了相应的技术控制措施。选取车站上方具有代表性的管线,以施工监控标准为依据,运用数值模拟方法,分析管线的沉降、侧移、变形和应力。监测数据显示,管线上方地表沉降均小于沉降绝对变化量和倾斜控制标准。数值模拟结果显示,管线刚度大,对开挖过程产生的地层变形有抵抗作用,施工过程出现管-土分离现象；管节间差异沉降和接头转角,以及计算最大拉、压应力均小于控制标准。(5)对扩挖施工引起地表沉降进行了深入分析,提出了风险应对措施。以施工过程监测数据为前提,结合北京地铁车站地表沉降控制基准值和现有北京市PBA法地铁车站地表沉降统计数据,并参考数值模拟结果,提出了合理的地表沉降控制标准,并按照三级控制的管理方法,分级分步进行地表沉降控制,研究已应用于指导工程施工方案的编制。更多还原

【Abstract】 The Jiangtai Station of Beijing Metro Line14is constructed by a large diameter shield machine, then the tunnel is enlarged by using Pile-Beam-Arch method (PBA method) to form main structure of the station. The method can effectively solve the contradictory between the interval shield tunnel construction and metro station construction. This is a new method and there is not similar engineer to be referred, therefore, it is necessary to do further research on construction risk, risk control technology, transformation of structure stress, influence on environment in the construction process, and so on.(1) The enlarging construction schemes are compared and selected in the aspect of engineering economy and technology, and the numerical simulation method is used to select the optimal scheme. On the basis, the risk sources are identified and risk control technology measures are put forward in the process of enlarging large diameter shield to build metro station by PBA method.(2) Due to the main structural body of enlarging station locates in the shield construction disturbance region, in order to analyze reasonably construction mechanics in the enlarging process, the strata mechanical parameters are anti-analyzed and obtained according to the monitoring data of ground surface settlement caused by shield construction. The result shows the parameter accords the actual engineering and the conclusion has theoretical and practical significance for subsequent enlarging construction process.(3) The three-dimensional discontinuous contact model is used to precisely simulate the enlarging construction process and study the risk sources of the main structure of station——the force of the four kinds key joints including segment joints, connection between locks of Key segments, connection between longitudinal beams and segments, connection between primary linings or steel support and segments. The result shows, stratum load and structural force are transferred by connecting joints and the structure is almost steady.On the basis of ascertaining the force and deformation of structural key joints, the force transformation rules in the critical construction steps and the influence on the whole structure, the risks are controlled in the aspect of engineering technology and the technology measures ensure the station structure safety and stability in the enlarging construction process.(4) The influence of enlarging construction to the adjacent underground pipelines is studied in detail. The corresponding technology control measures are put forward. The representative pipelines above the station are selected, and based on the construction monitoring data, the numerical simulation method is used to analysis the settlement, lateral displacement, deformation and stress of pipelines, the influence on adjacent pipelines is detailed in the construction process of station. The monitoring data shows, the ground surface settlement above the pipelines is less than the control standard of absolute settlement change value and tilt value. The numerical simulation result shows, the stiffness of pipeline is large and the pipelines can resist the stratum deformation in the excavation process. The separation phenomenon between pipeline and soil appears. The differential settlement and joint angle of pipeline nodes are less than control standard, and calculation values of maximum tensile and compressive stress are also.(5) The rule of ground surface settlement by the enlarging construction is analyzed deeply, and risk countermeasures are put forward. In the premise of the monitoring data of shield construction process, the reasonable ground settlement control standard is put forward combining with the ground surface settlement control reference value of Beijing metro station and the statistic data of existing metro station constructed by PBA method statistics data in Beijing, and referencing the result of numerical simulation. In accordance with the three class control management methods, the ground surface settlement is controlled step by step. The result has been used to guide compilling the engineering construction scheme.更多还原