【作者】 卜建清；

【导师】 孙宁；

【作者基本信息】 中国铁道科学研究院 ， 桥梁与隧道工程， 2011， 博士

【摘要】 随着城市升级改造和城市化建设的推进,基础设施建设不断完善,新修建的地下结构穿越既有结构基础所在空间的情况越来越多,鉴于地下结构物本身的重要性和既有结构使用功能的不可改变性,托换就成了最好的选择方案。在诸多托换工程中,复杂地质和动荷载条件下的托换工程难度最大,风险也最大。天津津滨轻轨桥梁墩柱托换工程是典型的动荷载托换,桥梁下部墩柱托换施工及基坑开挖与地道箱体施工对轻轨桥梁和线路以及列车运营具有一定的影响,同时上部运营轻轨列车的振动对托换施工也有影响,而且两方面的影响是耦合在一起的,故在施工过程中需要兼顾轻轨桥梁与运营安全和托换工程施工质量及安全两个方面。论文以该托换工程为研究对象,在结构时变理论的指导下,对风险分析与预防措施、结构设计、施工工艺、建模计算、试验研究、监测与控制、托换完成之后轻轨桥梁评估等环节的关键问题进行了比较系统的分析。首先,在全面分析托换工程设计与施工潜在风险点的基础上,制定了涉及各个参建单位的风险控制措施,设计了托换施工的风险事故应急体系和施工应急预案,为托换工程安全顺利的实施提供指导。然后,介绍了津滨轻轨桥梁墩柱托换工程的方案选择、设计思路以及托换结构设计成果,详细地阐释了从托换桩钻孔施工、托换大梁施工、千斤顶加载预顶升、墩柱切割与荷载转换、基坑开挖与地道箱体施工、托换桩与托换大梁固结施工等主动托换施工工艺、需要关注的关键问题及施工质量保证措施。其次,结合托换施工过程分析了托换结构的“时变”过程与特征,详细地说明了各种“时变”因素的分析方法,并用Ansys和Midas Civil软件建立模型模拟分析了托换节点的受力状态和各施工阶段托换结构的应力与变形,提出了为保证工程质量和轻轨运营安全应对托换结构“时变性”应该采取的“主动”措施。再次,给出了与津滨轻轨桥梁墩柱托换工程设计和施工密切相关的试验内容和结果,详细地设计了贯穿施工全过程、涵盖全方位的监测方案,包括监测指标、测点布设、监测频率、仪器设备、控制标准等内容,建立了以无线数据传输技术为基础的实时监测系统,将监测结果与数值模拟结果相结合实现施工控制,做到了真正意义上的信息化施工,重点讨论分析了监测与施工控制的实施过程和监测结果。最后,从静力学性能、动力学性能、使用性能等几个方面对托换施工之后的轻轨桥梁进行了较为全面的评估。不仅为轻轨桥梁的运营管理者进行维护管理提供了一个较为明确的依据,而且也进一步完善了托换理论。评估结果表明,桥梁墩柱托换不影响轻轨桥梁的正常使用,静态承载能力略有降低,而动力性能有所增强,托换对周围景观的不良影响可以通过绿化进行弱化。天津津滨轻轨桥梁墩柱托换工程的成功实施,对采用复杂结构实现车辆动荷载下桥梁结构基础托换的理论研究和实践应用具有一定的推动作用。更多还原

【Abstract】 Along with the urbanization and urban upgrading, the infrastructure constructions have been continuously improving. More and more new-constructed projects have to pass through the space where the basis of the original structure exists. The foundation underpinning is the best choice because of the importance of the underground structures and the function immutable nature of the existing structure. The underpinning projects have the most difficult and the greatest risk for the complex geological and dynamic load conditions.The project of the bridge pier underpinning for Jin-bin mass transit is a typical example of dynamic load underpinning. The bridge pier underpinning and the tunnel construction have a certain influence on the upper bridges, rail lines and train operations, at the same time, the vibration of the operating rains also have an impact on the underpinning construction, and the two aspects are coupled together. And therefore the operation safety and the construction quality need to be taken into account in the construction. The relatively systematic researches are made on this underpinning project in this thesis, based on the theories for time-varying structures, from several ways, such as the risk identification and preventive measures, structural system design, construction techniques, modeling calculations, experimental research, monitoring, and assessment on the bridge after the construction, etc.First of all, after analyzing the potential risks of the project implementation comprehensively, the risks control measures are proposed for all participations, and the emergency contingency plans are designed to care for the risk that may be occur in the construction. The above all will lead to the implementation of the project safely. Then, the scheme selection, the design ideas and the designed results are introduced for the underpinning project, respectively. The quality assurance measures are interpreted in detail for every construction steps, such as drilling holes of the new piles, constructing the lattice beams, hosting jack loading, cutting the replaced piers and load conversion, excavating pit, constructing tunnel, and mixing the piles and lattice beams, etc.Based on the analysis of the time-varying process and features for the underpinning architecture, a detailed description is made on how to consider the effects from the various time-varying factors. The Ansys and the Midas Civil software are employed to simulate the stress state of the underpinning-node and the mechanical behavior of the underpinning architecture in the construction. The active measures are proposed to ensure the construction quality and the safety of mass transit operations.The pilot programs and results closely related to the project are given. The monitoring plan, which is throughout the construction process and covers the full range, are designed in detail, including monitoring indicators, layout of the measuring points, monitoring frequency, equipment, control standards, etc. A real-time monitoring system is established by using of the wireless data transmission technology, and the monitoring results are combined with the numerical simulations to realize information construction. The monitoring implementation and of results are focused on.Finally, a comprehensive assessment of the bridge after the construction is made, from the static mechanical properties, dynamic behavior and the using performance. This not only gives the bridge manager a specific judgment for the maintenance and management, but also makes an improvement in the foundation underpinning theory. The assessment shows that the bridge pier underpinning does not affect the normal operation of mass transit. The static bearing capacity of the bridge decreased slightly, while the dynamic performance was enhanced, and the adverse impact on the surrounding landscape can be weakened by greening.The successful implementation of the project plays a catalytic role to the theories and practices of the active-underpinning for bridge foundation by complex structure under the moving vehicles.更多还原