软岩地层主梁式TBM撑靴侧壁围岩极限承载力分析

发布时间：2018-06-06 04:46

本文选题：TBM + 撑靴　；参考：《北京交通大学》2017年硕士论文

【摘要】：随着我国交通、水利等基础设施建设的快速发展,复杂地质条件下深长隧道采用TBM施工是最佳选择。开敞式TBM在穿越软弱地层时,由于侧壁围岩承载力不足会出现撑靴撑不住、围岩失稳等问题。为解决此问题,本文以辽西北供水工程(二段)施工四标为依托,通过数值模拟、理论分析和工程验证等方法对软岩地层主梁式TBM撑靴侧壁围岩的极限承载力进行了分析。论文的主要工作和研究成果如下:(1)通过大量查阅相关文献资料,对国内外TBM撑靴与侧壁围岩的相互作用的现有研究成果进行了分析和总结。总的来看,目前对TBM撑靴侧壁围岩极限承载力的研究比较匮乏,撑靴支撑力的预估主要依靠工程经验或者经验公式计算。(2)采用有限元和离散元耦合的数值模拟软件GDEM建立计算模型,参考现有经验公式以及现场实测数据选取计算荷载,分析了主梁式TBM撑靴侧壁围岩的变形规律,确定了软岩地层围岩的破坏模式为整体剪切破坏,破坏区域近似为两边小中间大的纺锤体,纺锤体靠近掘进方向一端稍短,远离掘进方向一端稍长。(3)根据GDEM计算确定的破坏模式,首先设定了侧壁围岩在撑靴作用下破坏面的几何形式,分析了破坏面上的应力分布;然后应用岩土体的塑性极限平衡理论,推导出了软岩地层主梁式TBM撑靴侧壁围岩极限承载力计算公式。(4)基于所推导的公式,对影响撑靴侧壁围岩极限承载力的6个因素(围岩的粘聚力、内摩擦角、极限承载力倾角、隧道的半径、撑靴的宽度和撑靴对应的圆心半角)进行了分析,结果表明围岩抗剪强度和撑靴与围岩接触面积为极限承载力的主要影响因素。(5)通过计算的TBM撑靴侧壁围岩极限承载力数值与现有经验公式和依托工程实测数据对比,撑靴承载力的安全系数(储备)一般在1.4～2.0之间,与现有相关规范的规定具有可比性,说明本文所推导公式的合理性。本文的研究结果对于TBM撑靴的设计及TBM在软岩地层掘进时承载力的选择具有重要指导意义。
[Abstract]:With the rapid development of transportation, water conservancy and other infrastructure construction in China, TBM is the best choice for the construction of deep and long tunnels under complex geological conditions. When open TBM passes through weak strata, the failure of supporting boots and the instability of surrounding rock will occur due to the insufficient bearing capacity of side wall rock. In order to solve this problem, the paper analyzes the ultimate bearing capacity of lateral wall rock of main beam type TBM boots in soft rock strata by numerical simulation, theoretical analysis and engineering verification based on the fourth standard of construction of the water supply project in northwest Liaoning Province. The main work and research results of this paper are as follows: (1) by consulting a large number of relevant literature, the existing research results on the interaction between TBM boots and side wall rock are analyzed and summarized at home and abroad. Generally speaking, the research on the ultimate bearing capacity of the surrounding rock of the side wall of the TBM brace boot is relatively scarce. The prediction of supporting force mainly depends on engineering experience or empirical formula calculation. (2) the calculation model is established by using the numerical simulation software GDEM, which is coupled with finite element and discrete element, and the calculated load is selected with reference to the existing empirical formula and the field measured data. The deformation law of lateral wall rock of main beam TBM brace boot is analyzed. The failure mode of surrounding rock in soft rock stratum is determined to be whole shear failure, and the failure area is approximately a spindle with small middle size on both sides, and the spindle is a little short near one end of the heading direction. Based on the failure mode determined by GDEM calculation, firstly, the geometric form of failure surface of lateral wall rock under the action of boot is set, and the stress distribution on failure surface is analyzed. Based on the plastic limit equilibrium theory of rock and soil mass, a formula for calculating the ultimate bearing capacity of surrounding rock around the lateral wall of TBM bracing boots in soft rock strata is derived. Six factors affecting the ultimate bearing capacity of the side wall rock of the boot, such as the cohesion of the surrounding rock, the angle of internal friction, the inclination angle of the ultimate bearing capacity, the radius of the tunnel, the width of the boot and the center half angle of the boot, are analyzed. The results show that the shear strength of surrounding rock and the contact area between supporting boots and surrounding rock are the main influencing factors of ultimate bearing capacity. The calculated values of the ultimate bearing capacity of side wall rock of TBM bracing boots are compared with the existing empirical formulas and the measured data of supporting engineering. The safety factor (reserve) of the bearing capacity of the supporting boots is generally between 1.4 and 2.0, which is comparable with the existing regulations, which shows the rationality of the formula derived in this paper. The results of this paper are of great significance for the design of TBM boots and the selection of bearing capacity of TBM in soft rock strata.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U455.43;U451.2

【参考文献】