基坑降水对周边环境影响的研究

发布时间：2018-06-18 23:14

本文选题：基坑降水 + Midas　；参考：《吉林建筑大学》2017年硕士论文

【摘要】：基坑降水确保基坑工程安全的同时势必会对坑外土体沉降、临近建筑物等周边环境产生影响,且降水引起渗流场的改变与周围应力场相互作用,增加了对影响结果准确预测的难度。本文依托北京某地铁车站基坑工程降水开挖实例为背景,借助Midas GTS有限元软件采用渗流分析及渗流-应力耦合分析,研究了基坑降水对周边环境的影响,成果如下:详细论述了国内外基坑降水对坑外土体沉降、临近建筑物等周边环境影响的理论研究现状。总结分析了地下水渗流对基坑工程的危害,概括了基坑降水的类型及适用条件,理论分析了基坑降水对周边环境影响的作用机理,给出了适用的降水导致地面沉降的计算方法。阐述了Midas GTS有限元软件运用在基坑工程中涉及的渗流分析及渗流-应力耦合分析基本原理,软件中材料本构模型及针对类似工程的建模分析方法。对照分析实际监测的结果及不同工况数值模拟结果,研究分析表明:在以坑外土体累积沉降为研究对象时,按照实例建模的工况三拟合效果最好,降水引起的坑外土体沉降值约占总沉降值的35%,开挖引起的沉降值约占65%。随着与基坑边缘水平距离的增加,累积沉降值呈现先增大后减小的趋势,此工程中最大值出现在约基坑开挖深度1.16倍处,对有降水的基坑工程分析时必须考虑降水的影响。以基坑坑底隆起为研究对象,坑底起初为弹性隆起,随降水开挖深度增加变为塑性隆起。以临近建筑物桩基变形及内力为研究对象,桩基沉降量随与基坑的距离增大而减小,形成差异沉降,引起建筑物倾斜。以地连墙水平位移及钢支撑内力变化为研究对象,随着降水开挖深度增大,地连墙整体变形特点为两端变形小,中间变形大的特点;钢支撑轴力最大值与围护结构水平位移量最大值出现位置相近,轴力变化与围护结构变形相符。
[Abstract]:While dewatering of foundation pit ensures the safety of foundation pit engineering, it will affect the settlement of soil outside the pit and the surrounding environment such as adjacent buildings, and the change of seepage field caused by precipitation will interact with the surrounding stress field. It increases the difficulty of accurate prediction of the influence results. Based on an example of dewatering excavation in a subway station in Beijing, the influence of foundation pit dewatering on surrounding environment is studied by means of seepage analysis and seepage stress coupling analysis using Midas GTS finite element software. The results are as follows: the present situation of theoretical research on the influence of foundation pit dewatering on the settlement of soil outside the pit and the surrounding environment such as adjacent buildings is discussed in detail. This paper summarizes and analyzes the harm of groundwater seepage to foundation pit engineering, summarizes the types and applicable conditions of foundation pit dewatering, theoretically analyzes the action mechanism of foundation pit dewatering on surrounding environment, and gives a suitable calculation method of ground subsidence caused by dewatering. The basic principles of seepage analysis and seepage stress coupling analysis in foundation pit engineering by Midas GTS finite element software are described. The material constitutive model in the software and the modeling and analysis method for similar engineering are described. Compared with the actual monitoring results and the numerical simulation results of different working conditions, the research and analysis show that when the cumulative settlement of soil outside the pit is taken as the research object, the three fitting results of the case modeling are the best. The settlement value of soil outside the pit caused by precipitation accounts for about 35% of the total settlement value, and the settlement value caused by excavation accounts for about 65% of the total settlement value. With the increase of horizontal distance from the edge of foundation pit, the cumulative settlement value increases first and then decreases. The maximum value of this project appears at about 1.16 times of excavation depth, and the influence of dewatering must be considered in the analysis of foundation pit engineering with dewatering. The bottom uplift of foundation pit is regarded as the object of study. The bottom of the pit is elastic uplift at first and becomes plastic uplift with the increase of the depth of dewatering excavation. Taking the deformation and internal force of the adjacent building as the research object, the settlement of the pile foundation decreases with the increase of the distance between the pile foundation and the foundation pit, resulting in differential settlement, which causes the building to tilt. Taking the horizontal displacement and the internal force of steel braces as the research object, with the increase of the depth of the dewatering excavation, the integral deformation of the ground connecting wall is characterized by small deformation at both ends and large deformation in the middle. The maximum axial force of steel bracing is similar to the maximum horizontal displacement of the enclosure structure, and the variation of axial force is consistent with the deformation of the enclosure structure.
【学位授予单位】：吉林建筑大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU753.66

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