【作者】 王海涛；

【导师】 戚蓝；

【作者基本信息】 天津大学 ， 水工结构工程， 2008， 硕士

【摘要】 随着城市建设的发展,高层建筑和大量的地下工程不断涌现,伴随而来的是大量的深基坑施工工程问题。并且基坑规模和深度都在不断增加,更是给工程设计人员带来了前所未有的挑战。天津地处于软土地区,地层软弱,地下含水丰富,本身地质条件就十分复杂。进行大型深基坑的施工难度和风险极大,同时又面临周围建筑物林立,地下管网密布,靠近道路施工等众多不利条件。因此必须在施工中保证围护结构安全,避免发生工程事故。对于深基坑工程而言,研究其开挖过程中的土体移动和支护体系的安全稳定是保证基坑工程安全的重要条件。本文以天津市南开区某大型深基坑工程为背景进行了相关的分析和研究;在总结以往基坑工程研究成果的基础上,对施工监测数据进行了整理分析,得出了相关结论。结合工程实际和利于有限元分析的角度,利用有限元软件ANSYS对该深基坑工程的双层环梁支护体系进行了三维非线性有限元分析,分析时把土体、围护桩和内环梁支撑体系看作一个整体,同时考虑围护结构和土体的相互作用,分析了在不同工况条件下基坑支撑体系的应力变化情况。通过与现场实测数据的对比表明,双层内环梁支护体系对于该基坑工程是适合的、安全的,这种支护形式适合在本地区的大型深基坑工程中应用。最后,本文依据灰色理论编制相关的程序,提出了基坑变形预测的方法;该方法也可以进行支护体系内力预测,取得了良好效果。通过上述研究,本文提出一种施工监测、有限元分析、不断预测的一种思想,使三者有机的结合起来,为实际工程提供理论依据和指导,有助于提高深基坑的设计水平和结构安全;并为类似的工程提供和积累宝贵经验。更多还原

【Abstract】 With the development of urban construction, more and more high-rise buildings and underground engineering spring up continuously, producing many problems in deep foundation pit construction. The increase of scale and depth of foundation pit brings unprecedented challenges to designers.Tianjin is located in soft soil area, and its geological conditions are quite complicated due to the weak formation and rich groundwater. The difficulty and risk of deep foundation pit construction is great, with some unfavorable conditions such as too many surrounding buildings, densely covered underground pipeline networks, short distance of roads, and so on. In order to prevent accidents, safety of the enclosure structures must be guaranteed in construction. In order to ensure the safety of deep foundation pit, researches should be done on the soil movements in excavation and the safety and stability of support system. In the paper, analysis and researches were done on a deep foundation pit in Nankai region, Tianjin Province. Based on the summary of previous researches, the arrangement and analysis on the inspection data in construction was done, and then some conclusions were achieved. Combined with engineering practice and finite element analysis, 3-d nonlinear finite element analysis was done on the double-layer ring beams of the foundation pit, using ANSYS. In the analysis, the soil, retaining pile and inside ring beam support system were regarded as a whole, with consideration of the interactions between support system and soil, the stress variation under different conditions was studied at the same time. The comparison between analysis results and field test data indicates that, it is safe to use the support system of double-layer inside ring beam in this project, which is suitable for other deep foundation pits in the region too. Then, according to the grey theory, program was established in the paper, and a method was proposed to predict the deformation and the internal force of the support system of the foundation pit.Based on the investigations above, the thought of combing with the construction monitoring, finite element analysis and continuously forecasting was proposed in the paper. The thought can provide theoretical basis and guidance for practical engineering, which is helpful to improve its design and safety, and it can also provide and accumulate valuable experiences for similar projects.更多还原