洞庭湖大桥锚碇基坑降水研究

发布时间：2018-10-12 11:07

【摘要】：伴随着高层建筑的建立和地下空间的应用深基坑工程应运而生,深基坑工程施工过程中往往会存在地下水,而地下水的存在对深基坑的安全将会产生严重的影响,因此在基坑开挖之前需采取合理的降水方法。本文以洞庭湖大桥锚碇基坑为例,采用室内变水头试验测定基坑土层的渗透系数,利用理论分析方法介绍了基坑的常用降水方法以及本工程所采用的基坑降水方案,并利用Midas GTS有限元软件分别模拟基坑降水开挖和不降水开挖两个施工过程,分析比较两种情况下不对称葫芦形地连墙支护体系的受力和变形特点,并在前两个锚碇基坑模型的基础上改变地连墙墙体厚度建立三维模型,研究不同厚度的墙体其自身受力和变形的特点。本文的主要工作:(1)查阅有关文献和资料,阐述了基坑降水方法的研究现状、地下连续墙的研究现状。(2)运用室内变水头试验测定锚碇基坑土层的渗透系数,本文分别测定了不同孔隙比和含水率条件下的土层渗透系数,并分析总结二者如何影响土层渗透系数。(3)介绍了常用的基坑降水方法以及本工程所采用的降水方法。(4)结合工程实际情况利用Midas GTS有限元软件对锚碇基坑分别建立考虑降水和不考虑降水两种情况下的三维基坑模型,模拟基坑每一步开挖过程,得出基坑降水对地连墙围护体系受力和变形的影响;并在此基础上模拟了地连墙墙体厚度不同时其受力和变形特点,增加墙体厚度在一定范围内可以阻止墙体发生变形。
[Abstract]:With the establishment of high-rise buildings and the application of underground space, groundwater often exists in the construction of deep foundation pit, and the existence of groundwater will have a serious impact on the safety of deep foundation pit. Therefore, reasonable dewatering method should be adopted before excavation of foundation pit. Taking the Anchorage foundation pit of Dongting Lake Bridge as an example, the permeability coefficient of soil layer of foundation pit is measured by indoor water head test, and the common dewatering method of foundation pit and the dewatering scheme of foundation pit adopted in this project are introduced by theoretical analysis method. Midas GTS finite element software is used to simulate the construction process of foundation pit dewatering excavation and non-dewatering excavation respectively, and the stress and deformation characteristics of asymmetric hyacinth earth connecting wall supporting system are analyzed and compared in the two cases. On the basis of the foundation pit model of the first two anchorages, a three-dimensional model is established by changing the thickness of the wall with different thickness, and the characteristics of its own force and deformation are studied. The main work of this paper is as follows: (1) referring to relevant documents and materials, the present research situation of foundation pit dewatering method and underground diaphragm wall are expounded. (2) the permeability coefficient of the soil layer of Anchorage foundation pit is measured by indoor water head change test. In this paper, the permeability coefficient of soil layer under different void ratio and water content is measured respectively. And how to influence the soil permeability coefficient is analyzed and summarized. (3) the commonly used foundation pit dewatering method and the dewatering method adopted in this project are introduced. (4) combined with the actual situation of the project, the Midas GTS finite element software is used to establish the Anchorage foundation pit separately. The three-dimensional foundation pit model considering precipitation and not considering precipitation, By simulating the excavation process of each step of foundation pit, the influence of foundation pit dewatering on the stress and deformation of the retaining system is obtained, and on this basis, the characteristics of force and deformation of the wall with different thickness are simulated. The wall deformation can be prevented by increasing the wall thickness within a certain range.
【学位授予单位】：长沙理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U445.553

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