长春地铁二号线西客站竖井深基坑开挖的变形监测及数值模拟

发布时间：2018-06-07 00:09

本文选题：深基坑 + 数值模拟　；参考：《吉林大学》2017年硕士论文

【摘要】：随着经济的发展,人口密度的增长,城市交通建设对于一个城市的意义至关重要。地下空间开始受到人们的关注,而地下工程的一种——地铁,作为大运量城市交通,对城市发展和交通规划有着化腐朽为神奇的能力。地铁涉及到的深基坑工程建设规模的扩大及开挖深度的增加均为岩土工程领域带来了许多理论及技术上的疑难问题。常用的指导深基坑开挖施工的方法有有限元数值模拟方法和现场施工监测方法。有限元方法可以预先对基坑开挖的工序进行演练,判断基坑的设计和施工工法是否安全可靠。但有限元方法受限于本构关系的选取、网格划分质量、边界条件的设定等问题,往往与工程实际情况有着不可忽视的差异,而现场施工监测则是从基坑支护结构的内力变形、基坑周围土体的位移等方方面面监控着整个基坑,从而避免基坑发生重大事故,同时测得的数据又可以和数值模拟对比分析来验证数值模拟方法的可靠性,反馈施工。本文以长春市地铁二号线西客站竖井深基坑工程为工程背景。在深基坑理论的基础上,结合工程实际,通过有限元模拟法和现场实际监测法来研究竖井深基坑开挖引起的周围土体变形规律,主要工作如下:(1)通过查阅文献,总结归纳基坑变形规律和变形机理;(2)介绍基坑监测的内容,阐述实际监测方案的制定方法,对实测数据进行统计分析,总结出基坑开挖变形的一些规律:长宽比较大的基坑开挖有着较明显的空间效应。位于基坑长边中点处的地表沉降最大,而基坑端部或基坑阴角附近的点,受到其空间效应的影响,会抑制其邻近区域的应力和变形的发展。基坑边缘致基坑外围方向上的地表沉降,先增大后减小。在开挖初期,各处的地表沉降速率较小;随着开挖越来越深,周边各点的地表沉降速率开始加大,总的沉降量也显著增加;当开挖到坑底后,周边各点的沉降速率开始减缓,但仍有增加,沉降总量逐渐趋于稳定;(3)通过有限元模拟基坑开挖过程,用实测数据进行比对,验证数值模拟的可靠性并分别建了4个挖深不同的基坑模型,进而分析基坑开挖变形与其开挖深度的关系。
[Abstract]:With the development of economy and the increase of population density, urban traffic construction is very important for a city. People began to pay attention to underground space, and underground engineering, a kind of subway, as a large volume of urban traffic, has the ability to degenerate into magic for urban development and traffic planning. The enlargement of the construction scale and excavation depth of the deep foundation pit involved in the subway have brought a lot of theoretical and technical problems to the geotechnical engineering field. The commonly used methods to guide the excavation of deep foundation pit are finite element numerical simulation method and site construction monitoring method. The finite element method can drill the excavation procedure in advance and judge whether the design and construction method of foundation pit is safe and reliable. However, the finite element method is limited by the selection of constitutive relation, the quality of mesh division, the setting of boundary conditions, and so on, which is often different from the actual engineering situation, and the field construction monitoring is based on the deformation of the internal force of the supporting structure of foundation pit. The displacement of soil around the foundation pit monitors the whole foundation pit so as to avoid serious accidents in the foundation pit. Meanwhile the measured data can be compared with the numerical simulation to verify the reliability of the numerical simulation method and feedback construction. This paper takes the deep foundation pit project of west passenger station of Changchun Metro Line 2 as the engineering background. On the basis of deep foundation pit theory, combined with engineering practice, the deformation law of surrounding soil caused by deep pit excavation is studied by finite element simulation method and field actual monitoring method. The main work is as follows: 1) by consulting literature, Summing up and summing up the deformation law and deformation mechanism of foundation pit, introducing the content of foundation pit monitoring, expounding the method of drawing up the actual monitoring scheme, and carrying on the statistical analysis to the measured data. Some rules of foundation pit excavation deformation are summarized: the excavation with large length and width has obvious spatial effect. The ground subsidence is the largest at the midpoint of the long side of the foundation pit, while the point near the end of the foundation pit or the corner of the pit is affected by its spatial effect, which will restrain the development of the stress and deformation in the adjacent area. The surface settlement on the periphery of foundation pit increases first and then decreases. At the beginning of excavation, the rate of ground subsidence is small; as the excavation gets deeper and deeper, the rate of surface settlement of the surrounding points increases and the total settlement increases significantly. When the excavation reaches the bottom of the pit, the settlement rate of the surrounding points begins to slow down. However, there is still an increase in the total settlement, and the total settlement tends to stabilize gradually.) by simulating the excavation process of foundation pit by finite element method and comparing with the measured data, the reliability of the numerical simulation is verified and four excavation models with different depth are built respectively. Furthermore, the relationship between excavation deformation and excavation depth is analyzed.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U231.3

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