煤矿斜井管片衬砌结构受力分析

发布时间：2018-12-26 17:10

【摘要】：随着国民经济的高速发展,煤炭能源消耗量逐年增长,许多煤矿已进入深部开采阶段。采用安全高效的TBM施工工法,以斜井形式快速进入开采工作面已成为目前深部煤矿开采的首选方案。在深部高地应力软岩中采用TBM工法修建煤矿斜井时,如何有效地减小作用在管片衬砌上的塑性形变压力及保证隧道在具有显著蠕变效应的软岩中的长期安全性,成为斜井设计和施工中的关键难题。本文以神华新街台格庙矿区TBM工法长距离试验斜井工程为依托,结合煤炭联合基金项目《复杂条件下TBM(盾构)修建煤矿巷道(斜井)的衬砌结构设计基础理论》,针对斜井"大埋深、软弱围岩"的特点,分别开展深埋软岩隧道基于应变软化模型的弹塑性分析、TBM施工合理灌浆滞后距离以及蠕变效应下的长期安全性研究,以期为单护盾TBM过软岩段施工难题提供参考。本文主要研究内容及成果如下:(1)基于应变软化模型,推导得到深埋圆形巷道受非轴对称荷载作用下的围岩位移、应力及塑性区范围的解析解。结果表明,应变软化模型的塑性区半径大于理想弹塑性模型的结果,但两者塑性区的分布规律一致。在此基础上,利用FLAC3D内置应变软化模型模拟隧道围岩,研究不同程度的粘聚力软化、内摩擦角软化及剪胀角软化对隧道开挖支护后的围岩位移、塑性区范围和管片应力的影响,结果表明,随软化程度的加大,围岩位移、塑性区范围及管片应力均有所增大,从而说明对深埋软岩隧道,考虑岩体的应变软化效应是十分必要的。(2)借助FLAC3D内置应变软化模型模拟隧道围岩,对采用管片预留可压缩层支护施工工艺的单护盾TBM开挖和支护隧道进行数值模拟,研究围岩位移和管片应力随豆砾石层灌浆滞后距离的变化规律。计算结果表明,随豆砾石层灌浆滞后距离的增大,围岩位移逐渐增大,而管片应力逐渐减小。在此基础上,以管片第一主应力最大值开始小于管片混凝土设计强度时的滞后距离为最短滞后距离,以围岩位移增长速率明显减小时的滞后距离作为合理滞后距离,由此确定了不同埋深情况下的豆砾石层合理灌浆滞后距离。(3)采用FLAC3D内置Burgers黏弹塑性蠕变本构模型,对大埋深软岩隧道长期蠕变效应进行数值模拟研究。分析在不同埋深、不同侧压力系数情况下的煤矿斜井,在建成100年内围岩位移和管片应力随时间的变化规律,以研究隧道的长期安全性。
[Abstract]:With the rapid development of national economy, the consumption of coal energy increases year by year, many coal mines have entered the stage of deep mining. Using the safe and efficient TBM construction method to enter the mining face quickly in the form of inclined shaft has become the first choice of deep coal mining at present. How to effectively reduce the plastic deformation pressure acting on segment lining and ensure the long-term safety of tunnel in soft rock with significant creep effect when TBM method is used to build inclined shaft in deep soft rock with high ground stress, how to effectively reduce the plastic deformation pressure acting on segment lining. It has become a key problem in the design and construction of inclined wells. In this paper, based on the TBM long distance test inclined shaft project in Shenhua Xinjie Taigemiao mining area, the basic theory of lining structure design of coal mine roadway (inclined shaft) built by TBM under complex condition is combined with the coal joint fund project <. In view of the characteristics of "large buried depth and soft surrounding rock" in inclined well, the elastic-plastic analysis of deep buried soft rock tunnel based on strain softening model, the reasonable grouting lag distance of TBM construction and the long-term safety study under creep effect are carried out respectively. In order to provide a reference for the construction of single shield TBM soft rock section. The main contents and results of this paper are as follows: (1) based on the strain softening model, the analytical solutions of the displacement, stress and plastic zone range of surrounding rock of deep buried circular roadway under the action of non-axisymmetric loads are derived. The results show that the plastic zone radius of the strain softening model is larger than that of the ideal elastoplastic model, but the distribution of the plastic zone is consistent between the two models. On this basis, the FLAC3D strain softening model is used to simulate the surrounding rock of the tunnel. The effects of different degrees of cohesive softening, internal friction angle softening and shear expansion angle softening on the displacement, plastic zone range and segment stress of the surrounding rock after the excavation of the tunnel are studied. The results show that with the increase of softening degree, the displacement of surrounding rock, the range of plastic zone and the stress of segment are all increased. It is very necessary to consider the strain softening effect of rock mass. (2) with the help of FLAC3D strain softening model to simulate the surrounding rock of tunnel, the excavation and supporting tunnel of single shield TBM with segment reserved compressible layer are numerically simulated. The variation of surrounding rock displacement and segment stress with the lag distance of bean-gravel grouting was studied. The results show that the displacement of surrounding rock increases gradually and the stress of segment decreases with the increase of the lag distance of grouting in the pea gravel bed. On this basis, when the maximum of the first principal stress of the segment begins to be less than the design strength of the segment concrete, the minimum lag distance is taken as the minimum lag distance, and the lag distance of the displacement growth rate of surrounding rock is taken as the reasonable lag distance. Therefore, the reasonable grouting lag distance in different buried depth is determined. (3) the long-term creep effect of soft rock tunnel with large buried depth is studied by using FLAC3D built-in Burgers viscoelastic-plastic creep constitutive model. In order to study the long-term safety of tunnel, the variation law of surrounding rock displacement and segment stress with time within 100 years after completion of inclined shaft in coal mine under different buried depth and different lateral pressure coefficient is analyzed.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD55

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