【作者】 李树清；

【导师】 潘长良； 王卫军；

【作者基本信息】 中南大学 ， 安全技术及工程， 2008， 博士

【摘要】 深部煤巷围岩控制是煤矿深部开采的技术难题之一。在分析深部煤巷矿压显现特征的基础上,结合现有围岩控制理论成果,提出了内承载结构和外承载结构的概念,建立了内、外承载结构模型,采用实验室实验、理论分析、数值模拟和现场观测等手段对深部煤巷围岩稳定性控制机理进行了系统的研究,主要研究内容和结果如下:(1)通过分析岩石软化、扩容、蠕变、松弛和长时强度等力学性质,得出了它们与围岩应力场演化的关系。进行变应力路径下的岩石峰后蠕变试验,结果表明:损伤程度影响峰后蠕变特性,损伤程度越大,蠕变速率越快,蠕变失稳时间越短;围压增量可以从根本上改变峰后蠕变特性,降低蠕变速率,延长蠕变失稳时间,促使峰后蠕变由非稳定蠕变向稳定蠕变转化。这些规律为破裂区围岩稳定性分析和控制提供了理论依据。(2)对深部巷道围岩深基点位移观测数据进行分析,得出围岩应变的空间分布具有波状特征;通过数值模拟分析,得出深部煤巷围岩应变、围岩应变软化系数和围岩应力的空间分布均具有波状特征,且它们三者之间存在有机的联系。结合围岩变形观测和数值模拟的结果,分析得到了内、外承载结构在受力、变形及性状等方面的力学特征,为在工程应用中界定外承载结构提供了依据。(3)建立了圆形巷道内、外承载结构相互作用弹塑性理论模型,得到了围岩塑性区和破碎区半径、围岩应力及围岩位移的表达式。建立了煤巷煤帮内、外承载结构相互作用弹塑性理论模型,推导了煤帮塑性区宽度、煤帮围岩应力、煤帮水平位移的表达式。应用圆形巷道和煤帮内、外承载结构相互作用弹塑性理论分析结果,推导了外承载结构有关特征参数的表达式,揭示了外承载结构特征参数与巷道围岩稳定性的关系,以及内承载结构支护强度与外承载结构特征参数的关系。(4)进行三维数值计算,研究了深部煤巷开挖、支护的空间效应,得出无支护、锚杆支护和锚杆锚索支护巷道外承载结构形成的规律,分析了锚杆支护参数对外承载结构形成过程的影响。建立圆形巷道粘弹塑性软化分析模型,得到了围岩塑性区和破碎区半径、围岩应力、围岩位移及外承载结构特征参数的表达式,分析了外承载结构随时间的演化过程及内承载结构所起的作用。建立煤帮外承载结构时间效应分析模型,推导了煤帮塑性区应力和煤帮外承载结构内边界位置的表达式,分析了煤帮外承载结构随时间的移动过程及内承载结构支护强度的影响。(5)提出了外承载结构稳定的条件和巷道围岩稳定的条件,探讨了内承载结构促使外承载结构稳定的机理。分析了锚杆支护、注浆加固、支架支护等形式内承载结构的时间效应、承载能力和支撑作用效果;分析了锚索支护对内、外承载结构的作用。根据内承载结构作用机制的差异,将内、外承载结构耦合过程分为两个阶段,提出了每个阶段的支护原则和支护方法。(6)通过平项山煤业集团四矿深部煤巷围岩控制的工程实践对研究结果进行了验证。更多还原

【Abstract】 Strata control around coal drift is one of the technological difficulties for deep coal mining. Combing the existing theoretical results, new concepts of "inner bearing structure" and "outer bearing structure" are put forward and an inner-outer bearing structure model is constructed based on the analysis to the characteristics of strata behaviors. On the basis, systematic research is made on the stability control mechanism of this kind of surrounding rock through lab tests, theoretical analysis, numerical simulation and field observations. The main content is as follows:1. New relationships between surrounding rock stress field evolution and rock properties are discovered. These properties contain softening, dilation, creep, relaxation, and long-term strength of the surrounding rock. The post-peak creep tests are conducted under different loading paths. The results show that: the post-peak creep properties are influenced by the damage degree. With the increase in damage degree, the creep velocity rises, while the creep collapsing time decreases. The creep properties will be changed fundamentally by the confining pressure increment. This leads to a decrease in the creep velocity and a prolongation of the creep collapsing time and hence makes the conversion of creep types from the unstable to the stable. This supplies a theoretical basis for stability analysis of the surrounding rock in the fractured zone.2. Observations of the base displacement in deep roadways show that the strain distribution express flexuous characteristics. The numerical simulations show that the spatial distributions of strain, stress and the strain softening coefficient express flexuous characteristics. Moreover, they are interrelated closely. Also the mechanical states concerning the stress, deformation, properties etc. of the inner-outer bearing structure are analyzed and got, which provides a good basis for the recognition and definition of the outer bearing structure in engineering applications.3. An elastic-plastic theoretical model of circular roadways considering the interaction between the inner and the outer bearing structure is presented, based on which the expressions of stress, displacement and the radiuses of the plastic zone and the loose zone in the surrounding rock are derived. Furthermore, another theoretical model considering the same interaction is derived for coal sides in coal drifts. Based on this model, the expressions of stress, horizontal displacement and the plastic zone width of coal side are derived. Also, the expressions of characteristic parameters of the outer bearing structure are derived from the aforementioned analytical results, which reveals the relationship between surrounding rock stability of roadways and the characteristic parameters of the outer bearing structure, as well as the relationship between the support strength of the inner bearing structure and characteristic parameters of the outer bearing structure .4. The spatial effects of excavation and support in a deep coal drift are studied with 3D numerical simulations, from which the formation mode of the outer bearing structure is found under three conditions, namely without support, with rockbolt support and with combined support of rockbolt and cable. The effect of the support parameters on the formation process of the outer bearing structure is analyzed. A viscoelastic plastic-softening analytical model of circular roadways is created, and the expressions about plastic zone radius, loose zone radius, surrounding rock stress, surrounding rock displacement, and characteristic parameters of the outer bearing structure are obtained. The evolution of the outer bearing structure and the role of the inner bearing structure plays during this process are studied. A rheological model of the outer bearing structure in coal sides is constructed. The expressions of plastic zone stress and the inner boundary location of the outer bearing structure are derived. The moving process of the outer bearing structure in coal sides and the influence exerted by the support strength of the inner bearing structure are analyzed.5. A stabilization condition of the outer bearing structure and surrounding rock is put forward, based on which the mechanism that the inner bearing structure makes the outer bearing structure stability is discussed. The temporal effects, the bearing capability, and the support effect of the inner bearing structures formed through bolt support, grouting, and brace support are analyzed. The influences of the cable on the inner and the outer bearing structures are analyzed. According to the differences of the inner bearing structure in function mechanisms, the coupling process of the inner and the outer bearing structure is divided into two stages, the support principles and methods of each stage are proposed.6. The research results were validated in the engineering practice of strata control around deep coal drifts in the fourth coal mine of Pingdingshan Coal Industry Group.更多还原