北京地铁大红门车站基坑变形特征研究

发布时间：2018-01-18 13:13

  本文关键词：北京地铁大红门车站基坑变形特征研究　出处：《中国地质大学(北京)》2017年硕士论文　论文类型：学位论文

  更多相关文章： 地铁基坑 基坑变形 基坑监测 FLAC3D 数值模拟

【摘要】：随着我国1978年改革开放以来,经济的飞速增长,城市化进程带来的交通拥堵问题愈加突出,地铁建设是解决此问题行之有效的方法之一。但是,地铁建设会对周围环境产生很大的负面效应,最近几年地铁车站基坑施工引发的工程事故时有发生,这也警示我们对基坑变形的研究时时不能松懈。因此,基坑稳定性研究成为许多学者研究的一个热点课题。本文主要介绍了基坑工程目前的研究发展状况,该工程的工程概况、工程地质条件、开挖支护方案以及监测方案,然后对所得到的监测数据进行分析归纳,得出基坑的周围地表沉降、围护结构的变形以及内支撑轴力在时间上、空间上变化规律。最后简单介绍了数值模拟软件FLAC3D原理,详细介绍了基坑数值模拟模型的建立:包括计算范围、本构模型、结构单元、计算参数、边界条件以及施工开挖步骤,采用FLAC3D有限差分程序对大红门地铁车站基坑在开挖深度2.3m,10.3m,16.8m,20.1m,24.3m,27.0m处周围地表沉降,基坑支护结构水平方向上的位移和钢支撑轴力变化规律进行了模拟,最后与实际监测结果相比较,验证基坑变形普遍规律。本文的主要研究结果如下:空间上沉降曲线呈“烟斗状”;在距离基坑边缘相同距离情况下,基坑长边附近地面沉降值普遍大于短边附近地面沉降值;根据一级基坑变形控制标准地表沉降控制值应为30mm,本次监测结果显示地表沉降最大变形值为11.90mm,远低于控制值,基坑安全性较好。围护结构变形曲线整体上由“前倾型”逐渐向“弓形”发展,最后变化趋于稳定;基坑连续墙最大水平位移为13.52mm,发生在深度18m左右的位置,明显小于地连墙墙体水平位移累计变化控制值20mm,说明基坑明挖法开挖以及地连墙+内支撑支护体系能够较好地控制基坑的侧向变形,保证基坑工程的安全。总体上钢支撑的轴力会不断增大,并且第三道钢支撑的变化幅度最大。数值模拟计算结果同现场实际监测数据做对比总体上相对于实际值偏小,但是数值模拟计算得到的变形规律与实际监测得到的基坑变形规律基本一致,本文的模拟结果可为日后该地区其他工程设计和施工提供指导和参考。
[Abstract]:With the rapid growth of economy since the reform and opening up in 1978, the problem of traffic congestion brought by the process of urbanization has become more and more prominent. Subway construction is one of the effective methods to solve this problem. Subway construction will have a great negative effect on the surrounding environment. In recent years, engineering accidents caused by subway station foundation pit construction have occurred from time to time, which also warns us that the study of foundation pit deformation can not be relaxed. The research of foundation pit stability has become a hot topic for many scholars. This paper mainly introduces the current research and development of foundation pit engineering, the general situation of the project and the engineering geological conditions. Excavation support scheme and monitoring scheme, and then analysis and induction of the monitoring data, the ground subsidence around the foundation pit, the deformation of the retaining structure and the internal support axial force in time. Finally, the principle of numerical simulation software FLAC3D is briefly introduced, and the establishment of numerical simulation model of foundation pit is introduced in detail, including calculation range, constitutive model, structure element and calculation parameters. The boundary condition and the construction excavation procedure are used to excavate the excavation depth of the excavation depth of the excavation depth of 2.3m10. 3mand 16.8mb / m by using the FLAC3D finite difference program for the foundation pit of the Dahongmen subway station. The surface settlement around 24.3mm or 27.0m, the horizontal displacement of foundation pit support structure and the variation law of steel support axial force are simulated. Finally, the results are compared with the actual monitoring results. The main results of this paper are as follows: the settlement curve in space is "pipe shape"; In the case of the same distance from the edge of the foundation pit, the value of the ground settlement near the long edge of the foundation pit is generally larger than that near the short side. According to the first class foundation pit deformation control standard surface settlement control value should be 30 mm, this monitoring result shows the surface settlement maximum deformation value is 11.90 mm, is far lower than the control value. On the whole, the deformation curve of the retaining structure develops from "forward tilting" to "bow", and the change tends to be stable at last. The maximum horizontal displacement of the continuous wall of foundation pit is 13.52 mm, which occurs at a depth of about 18 m, which is obviously smaller than the cumulative control value of 20 mm in the horizontal displacement of the wall connected to the ground. The results show that excavation of foundation pit and bracing system can control the lateral deformation of foundation pit and ensure the safety of foundation pit engineering. In general, the axial force of steel braces will increase continuously. And the change of the third steel bracing is the biggest. Compared with the actual monitoring data, the numerical simulation results are smaller than the actual values. But the deformation law obtained by numerical simulation is basically consistent with the deformation law of foundation pit obtained by actual monitoring. The simulation results in this paper can provide guidance and reference for the design and construction of other projects in this area in the future.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U231.3;TU433
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本文编号：1441097