北京地铁8号线永定门外站深基坑水下开挖变形特性研究

发布时间：2018-11-19 12:15

【摘要】：随着城市化的发展,地下工程特别是深基坑工程在城市中的应用日益增多。为了解决遇到的新问题,越来越多的工法相继出现,基坑工程的发展远远超越了其理论发展的程度。这些新颖的工法是否合理,如何在实践应用中保持基坑的安全和变形的合理控制与经济性之间的平衡,有必要进行深入的研究。本文在前人对深基坑工程的研究的基础上,分析了基坑开挖过程中的变形机理,总结了基坑变形的自然因素、设计因素和施工因素。论文以北京地铁8号线三期永定门外站深基坑工程为项目依托,通过分析该工程的地表沉降、地连墙水平位移和内支撑轴力等现场监测数据,得出地连墙+内支撑结构支护下的深基坑变形规律。研究了该工程中基坑变形的时空效应,分析了不同工况下基坑变形的特点。结合本工程的特殊性,本文分析了基坑水下开挖和水下封底、坑内水的抽排和回灌等多种新型工况下基坑的变形特性,得出了基坑水下开挖的变形规律。利用Midas/GTS有限元数值模拟软件对实际工程进行了建模和分析,并将模拟结果与现场监测数据进行对比,验证了数值模拟的准确性并且更加直观的分析了该基坑的变形规律,通过数值模拟验证了分仓墙对基坑变形显著的约束作用。在验证数值模拟准确的基础上,利用数值模拟的手段,采用单变量分析法,对影响该基坑变形的各种因素进行分析,研究了地连墙厚度、地连墙嵌固深度、分仓墙布置形式对支护结构变形的影响,并且为地连墙设计提出优化建议;基于变形监测对基坑内土体m值进行反分析,对设计参数提出优化建议。
[Abstract]:With the development of urbanization, underground engineering, especially deep foundation pit engineering, is increasingly used in cities. In order to solve the new problems, more and more engineering methods have appeared one after another, and the development of foundation pit engineering has far exceeded its theoretical development. Whether these novel methods are reasonable or not and how to keep the balance between the safety and deformation of foundation pit and the economy of foundation pit in practice, it is necessary to carry on the thorough research. On the basis of previous researches on deep foundation pit engineering, this paper analyzes the deformation mechanism of foundation pit excavation, and summarizes the natural factors, design factors and construction factors of foundation pit deformation. Based on the deep foundation pit project of Yongdingmen Station in the third phase of Beijing Metro Line 8, the paper analyzes the site monitoring data such as ground subsidence, horizontal displacement of ground connection wall and internal support axial force. The deformation law of deep foundation pit is obtained under the support of ground-connected wall. The space-time effect of foundation pit deformation in this project is studied, and the characteristics of foundation pit deformation under different working conditions are analyzed. Combined with the particularity of this project, this paper analyzes the deformation characteristics of foundation pit under various new conditions, such as underwater excavation and bottom sealing, pumping and recharging of water in the pit, and obtains the deformation law of underwater excavation of foundation pit. Midas/GTS finite element numerical simulation software is used to model and analyze the actual engineering, and the simulation results are compared with the field monitoring data. The accuracy of the numerical simulation is verified and the deformation law of the foundation pit is analyzed more intuitively. Numerical simulation is used to verify the significant restraint effect of the partition wall on foundation pit deformation. On the basis of verifying the accuracy of numerical simulation, using the method of numerical simulation and single variable analysis, various factors affecting the deformation of the foundation pit are analyzed, and the thickness of the ground connecting wall and the depth of the embedded wall are studied. The influence of the wall layout on the deformation of the supporting structure and the optimization suggestions for the design of the ground connecting wall are put forward. Based on deformation monitoring, the m value of soil in foundation pit is back analyzed, and some suggestions for optimization of design parameters are put forward.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U231.3;TU473.2

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