城市暗挖隧道穿越既有桥梁的安全控制

发布时间：2018-02-28 06:57

本文关键词： 地层变形既有桥梁遮拦效应破坏模式桩基可靠度桥梁控制标准动态控制体系主动顶升遗传算法反分析预测　出处：《北京交通大学》2015年硕士论文　论文类型：学位论文

【摘要】：随着城市现代化进程的不断发展,新建隧道穿越既有桥梁的情形越来越不可避免,而由于隧道开挖产生的地层变形和应力释放必然会对既有桥梁产生扰动,从而威胁桥梁的使用和安全,因此,探究城市暗挖隧道穿越既有桥梁的安全控制理论和方法具有重要的现实意义。本论文在对国内外相关文献资料进行广泛调研的基础上,以北京地铁7号线工程为背景,采用理论分析、数值模拟以及现场实测相结合的方法,对城市暗挖隧道穿越既有桥梁的安全控制方法进行了深入系统的研究,得到了如下结论： (1)在分析地层变形与既有单桩相互作用关系的基础上,对隧道开挖条件下既有群桩的变形特性进行了详细的阐述,并采用数值模拟重点分析了群桩的遮拦效应,认为群桩的变形模式和受力特性明显区别于单桩,而呈现出其独有的特点。 (2)从承台的作用和土拱效应两方面论述了被动群桩受力和变形特性的特殊性。即在隧道开挖条件下,一方面承台对各个桩基的荷载进行了均衡化的再分配,另一方面对低位承台而言,承台还会改变桩基的荷载传递路径；而土拱效应则会促使桩间土体发生应力迁移,从而在局部造成桩基的应力集中,最终导致桩基受力和变形特性的改变。 (3)在考虑隧道开挖对既有桩基承载力影响的基础上,建立了桩基承载力的可靠度功能函数,并采用matlab编写的响应面计算程序对隧道开挖条件下桩基承载力的失效概率进行了计算。 (4)在对差异沉降下不同形式桥梁进行受力和变形特性研究的基础上,提出了基于损伤评估的既有桥梁控制标准的确定方法。 (5)从传统防护和主动防护两方面对隧道穿越既有桥梁施工的安全性控制原理进行了阐述。建立了新型的隧道、土体、桩基、上部结构四者之间的相互作用关系,并提出了基于主动顶升的新型的桥梁主动防护方法。 (6)建立了完整的隧道邻近既有桥梁施工的动态控制体系,并形成了该系统的技术流程。其核心在于桥梁风险状态的判定及其应对控制措施的选择。通过该控制体系可以提前对桥梁的穿越风险进行判定,并及时采取应对措施,从而达到保证被穿越桥梁安全的目的。 (7)针对常规加固措施只能被动应对、无法主动补偿桩基沉降的现状,研发了隧道穿越既有桥梁的主动顶升成套技术。该技术主要分为顶升方案设计、顶升系统布置、顶升监测系统、顶升施工、清场恢复五个步骤。 (8)在隧道穿越既有桥梁施工过程中,针对暗挖法隧道施工的具体特点,提出了基于反分析预测的动态预测控制方法。该方法是将变位分配和反分析预测结合在一起的一种动态控制方法,能够实现穿越施工过程中的科学预警、分级控制和主动应对,从而最大限度的避免了风险累计,防止危险发生。
[Abstract]:With the continuous development of urban modernization, it is more and more inevitable that new tunnels pass through existing bridges. However, the formation deformation and stress release caused by tunnel excavation will inevitably disturb the existing bridges. Therefore, it is of great practical significance to explore the theory and method of safety control for urban tunneling through existing bridges. In this paper, based on the extensive investigation of domestic and foreign literature, taking the Beijing Metro Line 7 project as the background, the method of combining theoretical analysis, numerical simulation and field measurement is adopted. In this paper, the safety control methods of urban tunnels crossing existing bridges are studied in depth and systematically, and the following conclusions are obtained:. 1) on the basis of analyzing the interaction between stratum deformation and existing single pile, the deformation characteristics of existing pile group under the condition of tunnel excavation are expounded in detail, and the blocking effect of group pile is analyzed by numerical simulation. It is considered that the deformation mode and mechanical characteristics of pile group are obviously different from that of single pile, but show their unique characteristics. (2) the particularity of the force and deformation characteristics of the passive pile group is discussed from the two aspects of the action of the cap and the soil arch effect, that is, under the condition of tunnel excavation, on the one hand, the load of each pile foundation is redistributed by equalization of the pile cap. On the other hand, for the low pile cap, the pile cap will change the load transfer path of the pile foundation, and the soil arch effect will promote the stress transfer between the piles, thus causing the stress concentration of the pile foundation locally. Finally, it leads to the change of load and deformation characteristics of pile foundation. On the basis of considering the influence of tunnel excavation on the bearing capacity of existing pile foundation, the reliability function function of pile foundation bearing capacity is established. The failure probability of pile foundation bearing capacity under the condition of tunnel excavation is calculated by using the response surface calculation program written by matlab. 4) based on the study of the stress and deformation characteristics of different types of bridges under differential settlement, a method for determining the control standards of existing bridges based on damage assessment is proposed. The paper expounds the safety control principle of tunnel crossing existing bridge construction from two aspects of traditional protection and active protection. A new type of interaction relationship among tunnel, soil, pile foundation and superstructure is established, and a new active protection method based on active lifting is proposed. A complete dynamic control system for the construction of existing bridges adjacent to the tunnel is established. The core of the system is the determination of bridge risk state and the choice of control measures. Through the control system, the bridge crossing risk can be judged in advance, and the corresponding measures can be taken in time. In order to ensure the safety of bridge crossing. In view of the fact that conventional reinforcement measures can only deal with the settlement of pile foundation passively and can not compensate the settlement of pile foundation actively, a complete set of active lifting technology for tunnel crossing existing bridges is developed. The technology is mainly divided into the design of jacking scheme and the arrangement of lifting system. Top-up monitoring system, jacking construction, field recovery five steps. In the construction process of tunnel crossing existing bridges, aiming at the concrete characteristics of tunneling construction, This paper presents a dynamic predictive control method based on back-analysis and prediction. The method is a dynamic control method which combines displacement assignment with back-analysis prediction. It can realize scientific early warning, hierarchical control and active response in the process of traversing construction. Thus to avoid risk accumulation to the maximum extent, prevent the occurrence of risk.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U456.3;U447

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