逆作法竖向围护结构变形分析

发布时间：2018-01-24 16:22

本文关键词： 逆作法深基坑数值模拟位移沉降　出处：《安徽建筑大学》2016年硕士论文　论文类型：学位论文

【摘要】：以合肥新交通大厦为背景,对深基坑逆作法施工的种类与特点、原理、施工的优缺点、国内外的发展情况、目前主要存在的问题、以及逆作法深基坑数值模拟的研究现状等问题进行总结;分析了深基坑在开挖过程中基坑竖向围护结构、基坑底部以及基坑四周地表的变形机理;探讨了土压力的种类和研究方法以及基坑支护结构的土压力分布规律和基坑支护机构的计算理论等,旨在为合肥新交通大厦逆作法基坑开挖提供一些理论和施工的指导。合肥新交通大厦位于合肥地铁一号线与二号线交汇处,而且合肥新交通大厦基坑紧挨合肥地铁一号线与二号线。此外,合肥新交通大厦不仅周围建筑物情况十分复杂,而且基坑面积大深度大,因此该基坑开挖难度大要求高。运用大型有限元分析软件MIDAS/GTS将大厦基坑开挖的全过程进行动态模拟,并将有限元软件模拟得出的数据与实测数据进行比较分析,主要有以下几点结论与见解:(1)逆作法大型深基坑的开挖过程中,基坑周围地表沉降表现出距离基坑边沿越远土体沉降量越小,距离基坑边沿越近土体沉降量大,也就是由近及远土体的沉降量由大到小。但并不是完全这样,基坑周围地表最大沉降处并不是发生在开挖基坑的边沿处,而是发生在距离基坑边沿有一段距离的地方。整个沉降曲线的大致形状与烟斗形状相似。(2)随着基坑开挖深度的不断增加,基坑底部土体发生了不同程度的回弹与隆起。基坑开挖深度越深,坑底的隆起与回弹越大。而且基坑底部土体隆起与回弹呈现出中间大两边小的情况。整个回弹与隆起的形状像一个略微突起的小山丘。(3)在基坑开挖的过程中,地下连续墙随着土体的不断卸载发生了一定程度的偏移变形和抬升。首先,地下连续墙发生了竖向抬升随着基坑开挖深度的加大抬升位移也加大。其次,基坑地下连续墙也发生了向基坑内部的水平位移,随着基坑深度不断增加,地下连续墙的水平位移也不断加大。基坑地下连续墙的最大位移处大约在基坑深度的中间位置。最后,大型逆作法深基坑的长边的水平位移变形比短边的水平位移变形要大。(4)在逆作法深基坑开挖过程中,整个地下连续墙不论是X方向还是Y方向的有效应力均随着基坑开挖深度的增加而增大。
[Abstract]:Taking Hefei New Traffic Building as the background, the types and characteristics, principles, advantages and disadvantages of construction, the development situation at home and abroad, and the main problems existing in the construction of deep foundation pit are discussed. And the current situation of numerical simulation of deep foundation pit is summarized. The vertical retaining structure of deep foundation pit, the deformation mechanism of the bottom of foundation pit and the surface around the foundation pit are analyzed. The types and research methods of earth pressure, the distribution law of earth pressure of foundation pit support structure and the calculation theory of foundation pit support mechanism are discussed. The purpose of this paper is to provide some theoretical and construction guidance for foundation pit excavation of Hefei New Traffic Building, which is located at the junction of Line 1 and Line 2 of Hefei Metro. Moreover, the foundation pit of Hefei New Traffic Building is close to Hefei Metro Line 1 and Line 2. In addition, Hefei New Traffic Building not only has very complex surrounding buildings, but also has a large depth of foundation pit area. Therefore, the excavation of the foundation pit is very difficult. The dynamic simulation of the whole excavation process of the building foundation pit is carried out by using the large-scale finite element analysis software MIDAS/GTS. The data obtained by the finite element software simulation is compared with the measured data. The main conclusions and opinions are as follows: 1) in the excavation process of large deep foundation pit. The surface settlement around the foundation pit shows that the farther away from the edge of the foundation pit, the smaller the amount of soil settlement, and the larger the amount of soil settlement near the edge of the foundation pit, that is, the settlement amount of soil from near to far is from large to small, but it is not completely so. The maximum settlement of the ground around the foundation pit does not occur at the edge of the excavation foundation pit. The shape of the settlement curve is similar to that of the pipe. (2) with the increasing of excavation depth, the settlement curve occurs at a distance from the edge of the foundation pit, and the shape of the whole settlement curve is similar to that of the pipe. The soil at the bottom of the foundation pit has been springback and uplifted to varying degrees. The deeper the excavation is, the deeper the foundation pit is. The bigger the heave and springback of the bottom of the pit, and the larger and smaller the middle side of the bottom of the foundation pit. The shape of the whole springback and uplift is like a small hill with a slight protruding. During excavation. Underground continuous wall with the continuous unloading of soil occurred a certain degree of offset deformation and uplift. First of all the underground continuous wall vertical uplift along with the increase of excavation depth uplift displacement also increased. Secondly. The underground continuous wall of foundation pit also has the horizontal displacement to the inside of the foundation pit, with the increasing of the depth of foundation pit. The horizontal displacement of underground diaphragm wall is also increasing. The maximum displacement of underground diaphragm wall is about in the middle of the depth of foundation pit. Finally. The horizontal displacement deformation of the long side of the large inverse deep foundation pit is larger than that of the short side.) during the excavation of the deep foundation pit with the inverse method, the horizontal displacement deformation of the long side is larger than that of the short side. The effective stress of the whole diaphragm wall increases with the increase of excavation depth, either in X direction or Y direction.
【学位授予单位】：安徽建筑大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TU753

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