太原地铁中心街车站深基坑降水开挖对周边地面变形影响研究

发布时间：2018-10-31 17:40

【摘要】：为了有效拓展城市发展空间，缓解地面交通压力，太原市于近年开展了地铁建设，而地铁2号线成为太原规划的首条地铁线路。以往实践表明，城市地铁建设容易引起周边地面的变形，严重时可能危及周围建筑及地下管线的安全。但太原市乃至整个山西地区此前从未进行过地铁建设，针对此类问题没有相关的经验可供参考，因此，研究太原地铁2号线建设对周边地面变形的影响是十分必要的。本文以太原地铁2号线中心街车站作为对象，收集整理了区域内的自然条件，水文地质背景等资料，了解了区域的地质环境和水文地质条件，在项目区进行了工程勘察，研究了项目区的工程地质及水文地质条件，通过野外抽水试验及室内土工试验，了解了项目区各个地层的物理力学指标与渗透性，通过勘察成果及试验所得数据，建立了研究区域的水文地质概念模型。以流固耦合理论为依托，运用FLAC3D将水文地质模型转化为空间三维结构模型并分别对不同工况下地层的水平位移与地表的沉降进行了模拟求解。通过分析上述模拟计算结果，得出不同工况下基坑在降水与开挖后引起周边地表变形的规律：在无支护的情况下，基坑降水开挖7m时，基坑发生大的水平变形，局部超过5m，基坑发生坍塌；基坑降水开挖时，基坑开挖面的水平位移相比其他区域更大；周边地表的沉降变形以基坑为中心呈环状向外扩展，其中基坑角落的区域变形范围较大，，为其他位置1.2～1.5倍；地面的沉降变形程度并不是越靠近基坑越大，最大沉降区域处于距基坑一定距离的位置，模拟显示，最大沉降区距基坑边缘约为7m；相比于不考虑耦合的计算结果，考虑耦合的计算方式与实际工程更为吻合；根据模拟结果，当选用地下连续墙搭配3道支撑作为支护结构时，地表的水平及沉降变形均减小到要求范围内。论文成果在一定程度上总结出了深基坑降水开挖引起周边地表变形的规律，为中心街车站合理选择支护方式以减少对周边地表变形的影响提供理论依据，为太原市类似的地铁工程在如何削弱对周边环境不利影响的方面提供了研究思路与方法，积累了研究经验。
[Abstract]:In order to effectively expand the space of urban development and relieve the ground traffic pressure, Taiyuan City has carried out subway construction in recent years, and Metro Line 2 has become the first subway line planned in Taiyuan. The past practice shows that the construction of urban subway is easy to cause the deformation of the surrounding ground, which may endanger the safety of the surrounding buildings and underground pipelines. However, Taiyuan City and even the whole Shanxi area have never carried out subway construction before, so it is necessary to study the influence of Taiyuan Metro Line 2 construction on the surrounding ground deformation. Taking the Central Street Station of Taiyuan Metro Line 2 as the object, this paper collected and sorted out the natural conditions, hydrogeological background and other data in the area, understood the regional geological environment and hydrogeological conditions, and carried out engineering survey in the project area. The engineering geology and hydrogeological conditions of the project area are studied. Through field pumping test and indoor geotechnical test, the physical and mechanical indexes and permeability of each stratum in the project area are understood, and the survey results and the data obtained from the test are obtained. The hydrogeological conceptual model of the study area is established. Based on the fluid-solid coupling theory, the hydrogeological model is transformed into a three-dimensional spatial structural model by FLAC3D, and the horizontal displacement and ground subsidence under different working conditions are simulated and solved respectively. By analyzing the simulation results above, the rules of ground deformation caused by dewatering and excavation under different working conditions are obtained: when the foundation pit is dewatering and excavating for 7 m, the foundation pit has a large horizontal deformation, and the local deformation exceeds 5 m. Collapse of foundation pit; The horizontal displacement of excavation surface is larger than that of other regions during dewatering excavation. The settlement and deformation of the surrounding surface is circumscribed in the center of the foundation pit, and the deformation range in the corner of the foundation pit is larger, which is 1.5 times as large as that in the other positions. The settlement deformation degree of the ground is not more and more close to the foundation pit, and the maximum settlement area is located at a certain distance from the foundation pit. The simulation shows that the maximum settlement area is about 7 m from the edge of the foundation pit. Compared with the calculation results without considering coupling, the calculation method of considering coupling is more consistent with the actual engineering. According to the simulation results, the horizontal and settlement deformation of the ground surface can be reduced to the required range when the underground continuous wall is selected with three braces as the supporting structure. To some extent, the paper summarizes the law of surface deformation caused by dewatering excavation of deep foundation pit, which provides a theoretical basis for the reasonable selection of supporting methods to reduce the influence on the surrounding surface deformation at the central street station. This paper provides the research ideas and methods for the similar subway projects in Taiyuan on how to weaken the adverse effects on the surrounding environment, and accumulates the research experience.
【学位授予单位】：太原理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU753.66;TU433

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