深基坑双排桩支护结构开挖力学效应及稳定性影响因素研究

发布时间：2018-12-07 13:26

【摘要】：随各种大型综合交通枢纽的建设，应运而生了许多大型复杂深基坑，，双排桩支护结构因其施工方便、利于基坑土方开挖等诸多优点被越来越多的应用于深大基坑的支护，因此研究深基坑双排桩支护结构开挖力学效应、分析双排桩支护结构稳定性影响因素对于双排桩支护结构的优化设计及工程应用具有重要的意义。本文在总结国内外相关研究成果的基础上，以青岛市某综合交通枢纽深大基坑项目为工程背景，通过理论分析和数值模拟方法，对基坑开挖过程中的空间效应、双排桩支护结构的受力和变形特性、不同基坑开挖宽度、不同桩顶连接方式、不同桩顶连梁截面尺寸和不同布桩方式对双排桩支护结构变形和受力的影响进行了较为系统深入的研究。主要研究工作及研究成果如下： ①分析了现有关于双排桩支护结构的计算方法及各种计算方法的优缺点，重点阐述了数值分析方法的优越性。 ②采用数值分析方法，根据实际支护结构参数和基坑周边地质条件建立数值模型，依据施工方案模拟开挖过程，对比分析了大型基坑中不同位置处双排桩支护结构的变形和受力，给出了基坑坑角空间效应的影响范围及大型基坑中双排桩支护结构最不利分布区域。 ③在双排桩支护结构最不利分布区域中选取典型断面，对基坑开挖过程中双排桩支护结构的力学响应进行了研究，得出了基坑开挖过程中双排桩支护结构的变形和受力分布规律：靠近基坑坑底处的土方开挖对双排桩侧向变形影响较大，双排桩支护结构中前排桩分担的荷载要大于后排桩。 ④分别研究了基坑开挖宽度、桩顶连接方式、桩顶连梁截面尺寸和布桩方式对双排桩支护结构变形和受力的影响，研究结果表明：随着基坑开挖宽度的增大，双排桩支护结构受力和变形均增大；桩顶前后排连接时双排桩支护结构的支护效果与桩顶全连接基本相同；桩顶连梁截面尺寸为1d×0.5d（d为前后排桩桩径）时，双排桩支护结构整体受力最小且能有效控制变形；不同布桩方式对双排桩支护结构变形和受力的影响较大。
[Abstract]:With the construction of a variety of large integrated transportation hubs, many large and complex deep foundation pits have emerged. The double-row pile supporting structure is more and more applied to the deep and large foundation pit support because of its convenient construction and the advantages of the earth excavation of the foundation pit and so on. Therefore, it is of great significance to study the excavation mechanics effect of double-row pile supporting structure in deep foundation pit and analyze the factors affecting the stability of double-row pile supporting structure for the optimization design and engineering application of double-row pile support structure. On the basis of summarizing the related research results at home and abroad, taking the deep and large foundation pit project of a comprehensive transportation hub in Qingdao as the engineering background, through theoretical analysis and numerical simulation method, the spatial effect in the excavation process of foundation pit is studied. The stress and deformation characteristics of double-row pile supporting structure, different excavation width of foundation pit, different pile top connection mode, In this paper, the effects of different cross section sizes and different distribution modes of piles on deformation and force of double-row pile supporting structure are studied systematically and deeply. The main research work and research results are as follows: 1 the advantages and disadvantages of the existing calculation methods of double-row pile supporting structure and various calculation methods are analyzed, and the superiority of numerical analysis method is emphasized. (2) the numerical model is established according to the parameters of the actual supporting structure and the geological conditions around the foundation pit, and the excavation process is simulated according to the construction plan. The deformation and force of double-row pile supporting structure at different positions in large foundation pit are compared and analyzed. The influence range of the space effect of pit angle and the most unfavorable distribution area of double-row pile supporting structure in large foundation pit are given. In the most unfavorable distribution area of double-row pile supporting structure, the mechanical response of double-row pile supporting structure during excavation is studied. It is concluded that the deformation and stress distribution of double-row pile support structure during excavation: the lateral deformation of double-row pile is greatly affected by earthwork excavation near the bottom of foundation pit, and the load of front row pile is larger than that of rear row pile in double-row pile supporting structure. 4. The influence of excavation width, pile top connection mode, pile top connecting beam cross-section size and pile arrangement mode on deformation and force of double row pile supporting structure are studied respectively. The results show that: with the increase of excavation width of foundation pit, The stress and deformation of double-row pile supporting structure are increased; The supporting effect of the double row pile supporting structure is basically the same as that of the pile top full connection, when the section size of the pile top connecting beam is 1 d 脳 0.5 d (d is the front and rear row pile diameter), the overall force of the double row pile supporting structure is the least and the deformation can be effectively controlled. The influence of different pile arrangement on deformation and force of double row pile supporting structure is great.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU473.2

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