炭质板岩大断面隧道围岩稳定分析与控制技术

发布时间：2018-05-13 10:06

本文选题：隧道施工 + 炭质板岩　；参考：《北京交通大学》2014年硕士论文

【摘要】：摘要：广昆铁路秀宁隧道穿越板岩地层近4km,约占全隧的30%。炭质板岩呈薄层状、强度低,隧道施工极易产生滑坍、严重超挖、大变形等问题,围岩稳定性及其变形控制十分困难。为解决此难题,本文采用室内外试验、数值仿真、数值模拟和现场监测方法对炭质板岩围的破坏规律和稳定控制技术进行了研究,主要研究内容和结论如下： 1.通过查阅大量相关文献,对板岩的破坏规律以及破碎岩体的失稳机理进行总结分析。 2.对秀宁隧道炭质板岩段的炭质板岩进行现场取样,通过室内外的物理力学试验,得到了炭质板岩的含水率w、密度p、弹性模量E、抗拉强度Rm。 3.通过非连续介质软件GDEM模拟隧道在不同倾角炭质板岩地层中的开挖情况,得出炭质板岩从连续体到非连续体的渐进破坏过程,并分析总结了炭质板岩的变形破坏规律。 4.在秀宁隧道炭质板岩段施工过程中,对隧道的拱顶沉降和洞周收敛进行了现场监测,同时在隧道的代表性断面安放传感器,对钢拱架内力、喷射混凝土应力、围岩压力、初支与二衬间接触压力等进行了量测。现场监测结果显示,隧道在超前注浆加固后采用三台阶七步开挖方法进行施工,通过严格控制开挖进尺可以使隧道掌子面和周边围岩变形值控制在允许范围内,支护结构受力状态良好。 5.利用有限元软件MIDAS/GTS对洞内施工过程进行了数值模拟,其中考虑了两种不同开挖进尺。通过对比数值计算结果发现,隧道拱顶沉降、洞周收敛和洞周塑性区范围均随着开挖进尺的增大而增加,支护受力状态也发生了变化。 6.将现场监测数据与数值计算结果进行对比印证,发现两者吻合度较好,综合分析后可知超前注浆加固围岩及短进尺的三台阶七步开挖法能有效改善炭质板岩的工程性质,提高围岩的稳定性,减小隧道开挖时围岩和支护的变形,并能改善支护结构的受力状态,使隧道的开挖安全和快速进行。
[Abstract]:Abstract: Xiuning tunnel of Guang-Kun Railway is about 4 km across slate, accounting for 30% of the total tunnel. The carbonaceous slate is thin layer, low strength, easy to collapse in tunnel construction, serious overexcavation, large deformation and so on. The stability of surrounding rock and its deformation control are very difficult. In order to solve this problem, in this paper, indoor and outdoor tests, numerical simulation, numerical simulation and field monitoring methods are used to study the failure law and stability control technology of carbonaceous slate. The main contents and conclusions are as follows: 1. Through consulting a large number of relevant documents, the failure law of slate and the mechanism of instability of broken rock mass are summarized and analyzed. 2. The carbonaceous slate in Xiuning tunnel is sampled in situ. The moisture content, density p, elastic modulus E and tensile strength of carbonaceous slate are obtained by physical and mechanical tests in and out of the room. 3. The progressive failure process of carbonaceous slate from continuum to discontinuity is obtained by simulating the excavation of tunnel in different dip angle by discontinuous medium software GDEM, and the deformation and failure law of carbonaceous slate is analyzed and summarized. 4. During the construction of carbonaceous slate section in Xiuning tunnel, the settlement and convergence around the tunnel are monitored on the spot. At the same time, sensors are placed on the typical section of the tunnel, and the internal force of steel arch frame, the stress of shotcrete and the pressure of surrounding rock are put in the tunnel. The contact pressure between the initial branch and the second liner was measured. The monitoring results show that the tunnel is constructed by three-step seven-step excavation method after advanced grouting, and the deformation of tunnel face and surrounding rock can be controlled within the allowable range by strictly controlling the excavation advance. The supporting structure is in good stress state. 5. The finite element software MIDAS/GTS is used to simulate the construction process in the tunnel, in which two kinds of excavation advance are considered. By comparing the numerical results, it is found that the settlement of the tunnel vault, the convergence around the tunnel and the range of plastic zone around the tunnel increase with the increase of the excavation scale, and the stress state of the support is also changed. 6. By comparing the field monitoring data with the numerical calculation results, it is found that both of them are in good agreement. The comprehensive analysis shows that the three-step and seven-step excavation method with advanced grouting to reinforce surrounding rock and short advance rule can effectively improve the engineering properties of carbonaceous slate. The stability of surrounding rock is improved, the deformation of surrounding rock and support is reduced during tunnel excavation, the stress state of supporting structure is improved, and the excavation of tunnel is safe and fast.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U451.2;U455.49

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