某地下连续墙深基坑支护结构中钢筋混凝土支撑性能研究

发布时间：2019-03-13 12:21

【摘要】：随着城市轨道交通、地下空间的开发以及超高层建筑等项目的日益增多,深基坑工程也越趋频繁,其中,地下连续墙加钢筋混凝土内支撑的支护体系是一种较新的用于深基坑支护的方法。本文以南宁市某采用地下连续墙加钢筋混凝土内支撑支护结构的工程为例,利用有限元软件Midas GTS对该工程进行数值分析。在从最大支撑轴力、地下连续墙最大变形及最大地表沉降值等三个方面验证了支护方案可行的基础上,分别对横撑、纵撑和角撑的轴力随着施工阶段(荷载)的动态变化进行了分析,总结了支撑轴力随施工阶段的动态变化规律。针对目前基坑的规模大、施工工期长的特点,研究了温度作用对支撑性能的影响,工况包括升温和降温两个过程,从不同温差、支撑温度变化路径及支撑问的温度差异这三个方面研究了支撑轴力的动态变化规律及地下连续墙的变形规律。结果表明,温度作用不论是对于支撑轴力还是连续墙的变形,其影响都是非常大的。文章还探究了支撑的稳定性,推导了当支撑在自重、轴向压力与立柱抬升等多种因素共同影响下支撑中部总弯矩的计算式及支撑的挠曲线方程。通过计算得出当立柱抬升的位移达到0.030m时,由立柱抬升引起的弯矩可占到支撑中部总弯矩的82.91%,可知立柱抬升对于支撑中部总弯矩的影响亦是十分显著的。另外,从所推导的计算式可知基坑的宽度与支撑中部总弯矩有着密切的关系,因此还分析了基坑宽度和立柱抬升引起的支撑中部弯矩与支撑中部总弯矩的比值、支撑自重引起的支撑中部弯矩与支撑中部总弯矩的比值三者之间的关系。
[Abstract]:With the increasing number of projects such as urban rail transit, development of underground space and super-high-rise buildings, deep foundation pit projects are becoming more frequent, among which, The retaining system of underground continuous wall with reinforced concrete internal brace is a new method for deep foundation pit support. Taking a project with underground continuous wall and reinforced concrete internal bracing structure in Nanning as an example, the numerical analysis of this project is carried out by using the finite element software Midas GTS. On the basis of verifying the feasibility of the supporting scheme from three aspects: the maximum supporting axial force, the maximum deformation of the diaphragm wall and the maximum settlement value of the ground surface, the lateral brace is carried out separately. The dynamic variation of the axial force of the brace and the angle brace with the construction stage (load) is analyzed, and the rule of the dynamic variation of the axial force of the brace with the construction stage is summarized. In view of the characteristics of large scale and long construction period of foundation pit at present, the influence of temperature action on support performance is studied. The working conditions include heating up and cooling down, from different temperature difference. The dynamic variation law of supporting axial force and the deformation law of underground continuous wall are studied in three aspects: the path of supporting temperature change and the difference of supporting temperature. The results show that the effect of temperature on the axial force of bracing and the deformation of continuous wall is very great. The stability of the brace is also investigated, and the calculation formula of the total bending moment and the deflection curve equation of the brace under the influence of various factors, such as self-weight, axial pressure and column lift, are derived. The results show that the moment caused by column uplift can account for 82.91% of the total bending moment of the middle part of the bracing when the displacement of the column is 0.030m. It can be seen that the effect of the column lifting on the total bending moment of the middle part of the bracing is also very significant. In addition, the formula derived shows that the width of the foundation pit is closely related to the total bending moment in the middle of the bracing, so the ratio of the width of the foundation pit and the ratio of the central bending moment of the bracing to the total bending moment of the central bracing caused by the lifting of the column is also analyzed. The relationship between the ratio of the moment in the middle and the total moment in the middle of the brace caused by the weight of the brace.
【学位授予单位】：广西大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU753

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