“两墙合一”支护结构的变形及土压力研究

发布时间：2018-09-04 16:45

【摘要】：目前,在深基坑工程中常规的支护方法运用较多,由于不能被再次利用,浪费了许多建筑材料。“两墙合一”指地下连续墙既作为地下室外墙起到竖向承重作用,又作为挡土、防渗支护结构,它已经在实际中已经被广泛使用,但是它具有原来临时支护结构体系和作为永久结构的受力变形特性;土压力是作用在支护结构的主要荷载,对支护结构受力和变形的作用不言而喻。系统的研究“两墙合一”支护结构的变形和土压力对工程的设计和施工具有重要的指导意义。本文以昆明同德广场A7地块基坑工程为背景,利用有限元软件建立土、结构和周围环境共同作用的三维有限元模型,对该基坑施工过程进行了模拟分析,计算结果与实际监测数据基本一致,说明了该分析模型具有可靠性,并对数值模拟结果进行了详细的分析。主要的内容和结论有:(1)在前人研究的基础上,建立了位移-土压力计算公式,在非圆砾类较坚硬土时,计算的土压力与数值模拟结果比较接近,能为类似基坑设计时提供一定的参考价值。(2)连续墙侧移曲线由悬臂式向凸形转变,最大侧移值与对应工况开挖深度的比值在0.09%～0.32%之间,发生位置由墙顶移动到开挖面附近。随着基坑开挖,土压力的分布模式分为两种型态,分别是波状递增型态和斜阶梯伴有凹槽型态;土压力变化大致分为两部分,墙顶至三分之一墙高范围内土压力呈现增大的趋势,其余范围内土压力呈现减小的趋势;土压力与位移的关系可以归纳为双曲线关系、二次函数关系和斜直线关系(3)在上述工程实例基础上,分别分析了土体力学参数(粘聚力和内摩擦角)、地下连续墙厚度、悬臂开挖深度、支护结构插入比、邻近建筑物与基坑的距离、地面超载(超载大小、超载离基坑边的距离和超载长度)、邻近地下室(邻近地下室离地连墙的距离、邻近地下室的高度以及邻近地下室的宽度)影响因素对地下连续墙的变形和土压力的变化规律。
[Abstract]:At present, conventional support methods are widely used in deep foundation pit engineering, and many building materials are wasted because they can not be reused. "two walls in one" refers to the underground continuous wall, which has been widely used in practice as a vertical bearing function of the exterior wall of the basement, as well as a retaining and impervious supporting structure. But it has the original temporary support structure system and the deformation characteristics of the permanent structure, and the earth pressure is the main load acting on the support structure, and the effect on the force and deformation of the support structure is self-evident. The systematic study of deformation and earth pressure of "two walls in one" support structure is of great significance to the design and construction of engineering. In this paper, based on the foundation pit engineering of Block A7 of Tongde Square, Kunming, a three-dimensional finite element model of soil, structure and surrounding environment is established by using finite element software, and the construction process of the foundation pit is simulated and analyzed. The calculated results are basically consistent with the actual monitoring data, which shows that the analytical model is reliable, and the numerical simulation results are analyzed in detail. The main contents and conclusions are as follows: (1) on the basis of previous studies, a formula for calculating displacement-earth pressure is established. It can provide a certain reference value for the design of similar foundation pit. (2) the lateral displacement curve of continuous wall changes from cantilever type to convex shape, the ratio of maximum lateral displacement value to excavation depth of corresponding working condition is 0.09%, and the occurrence position moves from the top of the wall to near the excavating surface. With the excavation of foundation pit, the distribution pattern of earth pressure can be divided into two types, one is the increasing wave pattern and the other is the inclined ladder with grooves, and the variation of earth pressure is divided into two parts. From the top of the wall to the high range of 1/3 wall, the earth pressure increases, and the earth pressure decreases in the other areas, and the relationship between the earth pressure and displacement can be summed up as hyperbolic relationship. Quadratic function relation and oblique straight line relation (3) based on the above engineering examples, the mechanical parameters of soil (cohesion and angle of internal friction), the thickness of underground continuous wall, the depth of cantilever excavation, the insertion ratio of supporting structure are analyzed, respectively. Distance between adjacent building and foundation pit, ground overload (size of overload, distance of overload from side of foundation pit and length of overload), adjacent basement (distance of adjacent basement from wall to ground), The variation law of deformation and earth pressure of diaphragm wall is influenced by the height of adjacent basement and the width of adjacent basement.
【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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