深基坑土方开挖模拟优化及施工动态预测

发布时间：2019-04-02 04:36

【摘要】：近些年来,随着我国经济的发展,全国深基坑工程的规模与深度屡创新高,而基坑开挖作为基坑工程中的重要一环,涉及因素众多,研究起来难度较大。虽然我国已成功完成了一些大型基坑工程的设计及施工,但由于缺乏足够的理论知识及工程实践经验,基坑事故仍频繁发生,这其中,基坑开挖事故率占到基坑总数的1/4以上。可以说,基坑开挖阶段是控制基坑变形与基坑事故的最重要控制点。因此,利用计算机技术对基坑开挖过程进行数值模拟分析具有重要的工程意义,同时利用信息技术结合现场施工数据,反分析出准确的计算参数来对基坑施工过程进行动态预测,可大大减小基坑施工时的事故率,节省经济成本。本文结合合肥市恒大中心深基坑项目,利用MIDAS-GTS有限元软件,对可行的基坑开挖方案进行数值模拟分析,优选最佳方案;同时采用反分析方法,利用BP神经网络来反演土体力学参数,预测下一施工阶段基坑的变形特点并提出指导性的施工意见。本文的主要工作及结论如下:(1)总结归纳了基坑开挖中几种常用的开挖方式,介绍了各开挖方式的优缺点及适用性,给出了基坑开挖方案的初步设计流程,探讨了影响基坑开挖方案可行性的因素。(2)结合合肥市恒大中心深基坑工程背景,针对现场实际工程场地条件,基于基坑土方开挖理论,提出三种可行的土方开挖施工方案。(3)针对提出的三种可行的土方开挖施工方案,通过MIDAS-GTS有限元分析软件对三种可行的开挖方案进行数值模拟分析,从桩体深层水平位移、基坑周边地表沉降、桩顶水平位移、锚索轴力四个方面进行综合比较分析,推荐最佳开挖方案。(4)跟踪现场施工,采用现场开挖施工实测数据,应用反分析方法对开挖阶段进行关键土力学参数反分析,获得反分析出的土体弹性模量;基于反分析参数采用正分析方法预测后续施工阶段基坑的变形及稳定性,供施工时参考。(5)针对基坑中“坑中坑”开挖对基坑的影响,采用反演的关键力学参数,模拟预测“坑中坑”开挖对基坑支护体系变形的影响。
[Abstract]:In recent years, with the economic development of our country, the scale and depth of deep foundation pit engineering in China have repeatedly reached new highs. As an important link in foundation pit engineering, foundation pit excavation involves many factors, and it is difficult to study it. Although our country has successfully completed the design and construction of some large-scale foundation pit projects, due to the lack of sufficient theoretical knowledge and engineering practice experience, foundation pit accidents still occur frequently, among which, The accident rate of foundation pit accounts for more than 1 / 4 of the total foundation pit. It can be said that the excavation stage is the most important control point to control the deformation and accident of foundation pit. Therefore, using computer technology to carry on the numerical simulation analysis to the foundation pit excavation process has the important engineering significance, at the same time uses the information technology to combine the field construction data, The accurate calculation parameters can be used to predict the process of foundation pit construction dynamically, which can greatly reduce the accident rate and save the economic cost in the construction of foundation pit. Based on the deep foundation pit project of Hefei Evergrande Center, this paper makes use of MIDAS-GTS finite element software to carry on the numerical simulation analysis to the feasible foundation pit excavation scheme, and optimizes the best scheme. At the same time, the inverse analysis method and BP neural network are used to invert the mechanical parameters of soil, to predict the deformation characteristics of the foundation pit in the next construction stage and to put forward some instructive suggestions for the construction of the foundation pit. The main work and conclusions of this paper are as follows: (1) several common excavation methods in foundation pit excavation are summarized, the advantages, disadvantages and applicability of each excavation mode are introduced, and the preliminary design flow of foundation pit excavation scheme is given. The factors that influence the feasibility of foundation pit excavation scheme are discussed. (2) combined with the background of Hefei Evergrande Center Deep Foundation Pit, according to the actual site conditions, based on the excavation theory of foundation pit earthwork, Three kinds of feasible earthwork excavation construction schemes are put forward. (3) according to the three feasible earthwork excavation construction schemes, three feasible excavation schemes are numerically simulated and analyzed by MIDAS-GTS finite element analysis software. Based on the comprehensive comparison and analysis of the deep horizontal displacement of the pile body, the settlement of the surface around the foundation pit, the horizontal displacement of the pile top and the axial force of the anchor cable, the optimum excavation scheme is recommended. (4) following the site construction and adopting the measured data of the site excavation construction, The inverse analysis method is used to analyze the key soil mechanical parameters in the excavation stage, and the elastic modulus of the soil is obtained. Based on the inverse analysis parameters, the forward analysis method is used to predict the deformation and stability of the foundation pit in the follow-up construction stage for reference. (5) in view of the influence of "pit-in-pit" excavation on the foundation pit in the foundation pit, the inverse key mechanical parameters are adopted. The influence of "pit in pit" excavation on the deformation of foundation pit supporting system is simulated and predicted.
【学位授予单位】：武汉理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU753

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