北京地铁工程施工对既有市政桥梁基础的影响及评估研究

发布时间：2018-05-13 07:03

本文选题：邻近度 + 地铁工程　；参考：《北京交通大学》2015年博士论文

【摘要】：北京市目前正处于地铁建设的高峰期,北京地铁2015年总里程将超过700公里。市区内密集的高层建筑、高架桥梁大多采用桩基础。地铁工程由于受线路走向、地下空间等限制,有时不可避免地要从这些桩基的下方、侧面甚至在桩位处通过。本文以北京地铁四号线为例,从邻近度的概念出发,研究了地铁区间、车站地下结构施工对土体扰动引起周围地层变形和位移的估计方法、地层变形引起临近地下结构周围土体与桥桩发生相互作用,引起桥桩的变形和位移;研究了地铁明挖基坑、暗挖或盾构隧道施工对邻近桥桩的影响、以及不同影响因素对临近桥桩的侧向变形和弯矩的变化规律。通过桥桩较大侧向变形和内力对上部桥梁结构的影响研究,提出的桥桩侧向变形和内力的评估指标,补充和完善了现有的临近地铁工程的桥梁评估体系。通过研究,得出以下主要结论:(1)地铁工程与桥基的邻近度判别提出了邻近度的概念,利用模糊综合评价的基本思想确定了位置、距离、埋深以及结构重要性作为研究地铁施工对邻近桥梁桩基的主要影响因素。提出了邻近分区分度准则,为研究地铁施工对邻近桥梁桩基的影响分析提出了分析判断评价标准。(2)地铁施工对邻近桥梁基础影响的现场试验研究以北京地铁盾构区间穿越邻近既有桥梁桩基工程为依托,进行了邻近桥桩及地表的沉降监测试验,提出了各监测对象的沉降控制指标,对桥梁墩柱的监测数据进行重点分析。建立了盾构穿越邻近桥桩的数值分析模型,并针对桩身沉降、桩体侧向位移和周边土体沉降三个指标,将数值计算结果与实际监测数据进行相互验证。(3)地铁明挖基坑施工对桥基影响的参数研究基于FLAC3D数值分析软件,充分考虑桩土相互作用、建立三维有限元模型,对明挖基坑施工对临近桥桩的影响进行了数值分析。主要分析了几何因素、边界因素、物理因素等的影响;其中,几何因素包括基坑开挖深度、基坑与桩净距、坑外受影响桩的桩长;边界因素包括桩顶作用力、桩顶约束条件;物理因素包括土层物理参数、土层与桩体接触参数等。(4)地铁暗挖施工和盾构施工对邻近桥桩影响的参数研究用FLAC3D数值分析软件对地铁暗挖和盾构施工对临近桥桩的影响进行了参数研究。分别考虑了几何因素包括隧道上部土厚度、隧道与桩净距、桩长;边界因素包括隧道开挖的应力释放率、桩顶力;物理因素包括土层物理参数、土层与桩体接触参数等因素对地铁隧道临近桥桩的影响进行了数值计算模拟。(5)地铁工程临近桥基施工对既有市政桥梁影响的评估分析结合前述研究成果,提出相对完善的地铁邻近桥桩施工安全评估的方法步骤,进而提出了邻近桥桩的沉降控制标准,并且结合北京地铁6号线下穿京广桥工程的实际监测结果,提出了现有邻近桥桩评估体系的不足和完善建议。
[Abstract]:Beijing is at the peak of subway construction, with a total mileage of more than 700 kilometers in 2015. In the dense high-rise buildings in the urban area, most of the viaducts use pile foundation. Due to the limitation of track direction, underground space and so on, subway engineering sometimes inevitably passes from the bottom and side of the pile foundation even at the pile position. In this paper, taking Beijing Metro Line 4 as an example, starting from the concept of proximity, the method of estimating the deformation and displacement of the surrounding strata caused by soil disturbance caused by underground structure construction of subway sections and stations is studied. The ground deformation causes the interaction between the soil around the adjacent underground structure and the bridge pile, which causes the deformation and displacement of the bridge pile, and studies the influence of underground excavation, underground excavation or shield tunnel construction on the adjacent bridge pile. And the variation law of lateral deformation and bending moment of adjacent bridge pile with different influencing factors. Through the research on the influence of large lateral deformation and internal force of bridge pile on the upper bridge structure, the evaluation index of lateral deformation and internal force of bridge pile is put forward, which complements and perfects the existing bridge evaluation system near subway engineering. In this paper, the following main conclusions are drawn: 1) the concept of proximity degree is put forward by judging the adjacent degree between subway engineering and bridge foundation, and the position and distance are determined by using the basic idea of fuzzy comprehensive evaluation. The buried depth and the importance of the structure are the main factors which affect the pile foundation of the adjacent bridge. The neighbor partition criterion is proposed. In order to study the influence of subway construction on the pile foundation of adjacent bridges, the paper puts forward the criterion of analyzing and judging the influence of subway construction on the foundation of adjacent bridges. The field test study on the influence of subway construction on the foundation of adjacent bridges is based on the pile foundation engineering of Beijing metro shield section passing through adjacent existing bridges. The settlement monitoring tests of adjacent bridge piles and ground surface are carried out, and the settlement control indexes of each monitoring object are put forward, and the monitoring data of bridge pier columns are analyzed emphatically. The numerical analysis model of shield passing through adjacent bridge pile is established, and the three indexes of pile settlement, pile lateral displacement and surrounding soil settlement are discussed. Based on the FLAC3D numerical analysis software, the three-dimensional finite element model is established by fully considering the pile-soil interaction. The influence of excavation construction on adjacent bridge piles is numerically analyzed. The influences of geometric factors, boundary factors, physical factors and so on are mainly analyzed. Among them, geometric factors include excavation depth, net distance between foundation pit and pile, length of pile affected by pile outside the pit, boundary factors including pile top force, pile top constraint condition, and so on. Physical factors include soil physical parameters, Parameter study on the influence of Underground excavation and Shield Construction on adjacent Bridge piles; the influence of underground excavation and shield construction on adjacent bridge piles is studied by FLAC3D numerical analysis software. The geometric factors include the thickness of the upper soil, the distance between the tunnel and the pile, the length of the pile, the boundary factors including the stress release rate of the tunnel excavation, the top force of the pile, the physical factors including the physical parameters of the soil layer, The influence of the contact parameters of soil layer and pile body on the pile of adjacent bridge in subway tunnel is simulated numerically. 5) the evaluation and analysis of the influence of the construction of adjacent bridge foundation of subway project on the existing municipal bridge are combined with the above research results. This paper puts forward a relatively perfect method and procedure for safety assessment of adjacent bridge piles in subway construction, and then puts forward the settlement control standard of adjacent bridge piles, and combines with the actual monitoring results of Beijing Guangqiao Project under Beijing Metro Line 6. The shortcomings of the existing evaluation system of adjacent bridge piles and the suggestions for its perfection are put forward.
【学位授予单位】：北京交通大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：U231.3;U443.1

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