浅埋暗挖大断面黄土地铁隧道荷载作用特征研究

发布时间：2019-02-16 17:07

【摘要】：随着西安地铁建设的持续展开以及浅埋暗挖法的优越性，黄土地层浅埋暗挖大断面地铁工程将会越来越多。然而，由于黄土特殊的物理力学性质，黄土隧道的工程特征与普通隧道有相当大的差异，浅埋大断面黄土隧道的设计和修建技术尚需进一步的完善和改进。因此，本文以西安地铁三号线实体工程为依托，通过理论分析、现场测试、数值模拟等研究手段，对浅埋暗挖大断面黄土地铁隧道的荷载作用特征和支护结构受力特性展开研究，主要开展了以下工作：首先，广泛调查收集与本课题有关的文献，总结和归纳现有的浅埋暗挖工法、黄土隧道以及大断面地铁隧道的研究成果，为后续工作的展开奠定基础。其次，以西安地铁三号线咸~长区间为工程依托，进行全面系统的现场测试。通过在围岩及支护体系中布设压力盒、钢筋计、表面应变计、混凝土应变计等测试元件，对支护结构受力状态进行监测，获得了大量的试验数据。并根据实测结果，分析该大断面黄土地铁隧道的围岩压力及支护结构受力特性。主要得出了以下结论：接触压力整体上小下大，侧向压力及拱脚底部压力较大，拆撑及二衬的施作对其具有较大的影响；采用目前较为成熟和常用的浅埋围岩压力计算公式计算，其结果偏于保守；格栅拱架在支护初期喷射混凝土强度尚未完全形成及临时支撑拆除时支撑作用明显；中壁型钢受力显著，尤其是先行导洞，可见围岩应力主要通过先行导洞的开挖释放，分导洞错开开挖时，支护应及时封闭；初支与二衬承受荷载比例分别为35.32%和64.68%，二衬作为承载主体，，承担了大部分的荷载；不同位置混凝土内力差别较大，边墙及以上受压，仰拱处受拉。最后，采用有限元软件对依托工程进行仿真分析，用二维模型模拟了隧道的开挖和支护，分析研究浅埋暗挖大断面黄土地铁隧道支护结构受力特性，并与现场测试结果进行对比分析。本文的研究结果可为浅埋暗挖大断面黄土地铁隧道以及类似地下工程的设计及施工提供一定的理论依据和指导作用。
[Abstract]:With the continuous development of Xi'an subway construction and the superiority of shallow underground excavation method, there will be more and more subway projects with large cross-section of shallow buried excavation in loess layer. However, because of the special physical and mechanical properties of loess, the engineering characteristics of loess tunnel are quite different from those of ordinary tunnel, and the design and construction technology of shallow loess tunnel with large section still needs to be further improved and improved. Therefore, based on the Xi'an Metro Line 3 solid project, through theoretical analysis, field testing, numerical simulation and other research means, In this paper, the characteristics of load action and supporting structure of large section loess subway tunnel are studied. The main work is as follows: firstly, extensive investigation and collection of literature related to this subject. This paper summarizes and sums up the existing research results of shallow excavation method, loess tunnel and large section subway tunnel, which lays a foundation for the following work. Secondly, based on the salty ~ long section of Xi'an Metro Line No. 3, a comprehensive and systematic field test is carried out. By installing pressure box, steel bar meter, surface strain gauge and concrete strain gauge in surrounding rock and supporting system, the stress state of supporting structure is monitored and a large number of test data are obtained. Based on the measured results, the surrounding rock pressure and the mechanical characteristics of the supporting structure of the large section loess subway tunnel are analyzed. The main conclusions are as follows: the overall contact pressure is small and large, the lateral pressure and the bottom pressure of arch foot are large, the removal of brace and the application of second lining have great influence on it; The results of calculating the pressure of shallow surrounding rock by using the mature and commonly used formulas are conservative, the grid arch frame has not been fully formed in the initial stage of support, and the support effect is obvious when the temporary support is removed. The stress of the middle section steel is obvious, especially the pilot tunnel. The surrounding rock stress is mainly released through the excavation of the leading tunnel, and the support should be closed in time when the diversion tunnel is staggered and excavated. The ratio of initial support to second liner is 35.32% and 64.68% respectively. As the main bearing body, the second liner bears most of the load, and the internal force of concrete varies greatly in different positions, the side wall and above are compressed, and the inverted arch is pulled. Finally, the supporting engineering is simulated with finite element software, and the excavation and support of tunnel are simulated by two-dimensional model, and the mechanical characteristics of shallow buried large section loess subway tunnel support structure are analyzed and studied. And the results are compared with the field test results. The research results of this paper can provide certain theoretical basis and guidance for the design and construction of shallow buried large section loess subway tunnel and similar underground engineering.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U231;U451

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