土钉墙的变形对周边环境的影响

发布时间：2018-04-13 04:21

本文选题：土钉墙 + 周边环境　；参考：《昆明理工大学》2017年硕士论文

【摘要】：本文以昆明市盘兴博大基坑工程中的土钉墙支护剖面为研究对象,利用Midas/GTS有限元软件建立了土体、土钉墙支护结构和周边环境相互作用的三维有限元模型。在此基础上,分析了土钉的倾角、钉长、布置方式、密度和软土层在基坑中的位置对土钉墙的变形及周边环境的影响,最后研究了当坑底为软土时,增加土钉长度和不同预应力值下的预应力锚杆+土钉的改进支护方式对土钉墙的变形及周边环境的影响。主要工作和研究成果如下:(1)依据土钉墙工程实例利用Midas/GTS有限元软件建立模型,模拟土钉墙的施工过程得出模拟结果。通过模拟值与监测值对比验证模型的可靠性,同时对土钉墙及周边环境的变形结果进行分析。(2)土钉倾角在10°～30°区间内,倾角越小对变形控制越有利;在原支护结构的钉长上增加4m后,土钉的平均长度为基坑深度的1.15倍,达到了临界长度,如果再增加土钉的长度则土钉的内力几乎不发生变化,对控制变形的意义不大;在土钉总长度不变和土质较好的情况下,长短相间的布置方式对变形控制最有利,中部较长次之,造成变形最大的是上长下短的布置方式;在考虑变形控制要求和经济节约的前提下,土钉的间距在1.5m左右最优,当土钉的间距为0.5m时,出现了群钉效应,土钉密度过大也对变形控制非常不利。(3)厚度为2m的软土层在基坑中的位置越靠下时对变形控制越不利,其中软土的物理力学参数采用昆明地区典型的泥炭质土参数。当软土层位于基坑底部时,单纯靠增加土钉长度来控制土钉墙的变形效果没有采用预应力锚杆+土钉这种复合土钉墙的支护方式效果好。在一定预应力值区间内随着预应力的增加,对变形控制有积极的意义,当锚杆的预应力较大时,则加大锚杆作用范围之外土体变形,对变形控制不利。
[Abstract]:In this paper, the soil nailing wall supporting section in Panxing big foundation pit engineering of Kunming City is taken as the research object, and the three-dimensional finite element model of soil mass, soil nailing wall supporting structure and surrounding environment is established by using Midas/GTS finite element software.On this basis, the effects of inclination, nail length, layout, density and the position of soft soil in foundation pit on the deformation and surrounding environment of soil nailing wall are analyzed. Finally, when the bottom of the pit is soft soil,The influence of the improved support mode of prestressed anchor soil nailing on the deformation and surrounding environment of soil nailing wall with increasing the length of soil nailing and different prestress values.The main work and research results are as follows: 1) based on the example of soil nailing wall engineering, the model is established by using Midas/GTS finite element software, and the simulation results are obtained by simulating the construction process of soil nailing wall.The reliability of the model is verified by comparing the simulated value with the monitoring value. At the same time, the deformation results of soil nailing wall and surrounding environment are analyzed. 2) the inclination angle of soil nail is in the range of 10 掳~ 30 掳, the smaller the inclination angle is, the more favorable the deformation control is.The average length of soil nailing is 1.15 times of the depth of foundation pit, which reaches the critical length after increasing the nail length of the original support structure by 4 m. If the length of soil nailing is increased, the internal force of soil nailing will hardly change, which is of little significance for controlling deformation.Under the condition that the total length of soil nailing is constant and the soil quality is good, the arrangement with long and short phases is the most favorable to the deformation control, and the middle part is the second, and the biggest deformation is the arrangement of the upper length and the lower part.Considering the requirements of deformation control and economic saving, the spacing of soil nailing is about 1.5 m. When the spacing of soil nailing is 0.5 m, the group nail effect appears.The higher the density of soil nailing is, the more disadvantageous is the deformation control of soft soil layer with thickness of 2m in foundation pit. The physical and mechanical parameters of soft soil are based on the typical peat soil parameters in Kunming area.When the soft soil layer is located at the bottom of the foundation pit, the deformation effect of the soil nailing wall is controlled simply by increasing the length of the soil nailing. The supporting effect of the composite soil nailing wall is better than that of the prestressed anchor soil nailing.With the increase of prestress, it has a positive significance for deformation control. When the prestress of anchor rod is large, the deformation of soil outside the range of anchor action will be increased, which will be disadvantageous to deformation control.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU753

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