【作者】 卫晓君；

【导师】 石平五；

【作者基本信息】 西安科技大学 ， 矿业工程， 2009， 博士

【摘要】 岩石的局部化变形是岩土材料变形失稳的一个重要特征和致灾前兆。在开采扰动作用下,其局部化变形直接导致了岩石整体强度的降低,使工程岩体的承载能力下降。准确预测局部化失稳是实现安全开采的关键技术之一。要从本质上解决这一技术难题,就需要研究开采扰动区围岩和煤柱局部化破坏规律以及开采引起的局部化失稳与发展过程;利用先进监测方法,合理确定局部化失稳的多元指标信息,寻找条带开采局部化灾害预报与控制方法,这是煤炭安全开采中面临的一个重大的科学问题。本论文基于理论分析、煤柱体介质的物理力学性态声发射测试、物理相似模拟、三维数值模拟、现场监测等方法和手段,系统分析了由于局部自然和技术条件发生异常性的变化而导致局部化灾害,建立了监测体系,指导了生产实践,保证了安全开采。(1)现场工程调查表明,典型矿区条带开采区域煤层的赋存环境与顶板结构存在空间变异性。自然或工程的某些条件的局部变化可能导致保护工程的局部区域变形、局部位置强度劣化诱发工程失稳进而演化为灾害。(2)利用煤岩局部化损伤与破裂声发射实验,分析了煤样在不同加载与破裂阶段声发射特征统计规律。同时完成了黄土的物理指标与湿陷特征参数实验以及固结不排水条件下的三轴实验,得出了黄土物理指标统计规律,进一步揭示了岩(土)体具有局部化失稳并导致局部性灾害的可能性。(3)通过物理相似模拟和数值计算,深入分析了煤柱局部化变形导致局部区域破坏过程及演化规律。研究表明,由于个别缺陷煤柱的破坏,而导致的局部化灾害过程主要包括3个阶段,即缺陷煤柱的破坏阶段、煤柱破坏发展阶段和局部区域突发塌陷阶段。随着煤柱破坏发展,当冒落发展到基岩厚度不足以承担松散覆盖层重量时,在松散覆盖层作用下发生切顶灾害。地表和第四系水体破坏,就会造成矿井水灾。同时,相似材料模拟实验表明,由于存在个别的“缺陷煤柱”,造成应变软化导致局部化灾害的演化过程,可以认识到一些相关的关键技术问题。及早发现“缺陷煤柱”是防止局部化灾害的首要任务;层状围岩体的构成特征,是判断煤柱破坏发展阶段冒落高度的基础;顶板覆盖层含水体赋存层位及富水性,是判断煤柱破坏发展阶段是否发生水灾的依据;控制局部化灾害是优化条带开采设计的技术基础之一;松散层厚度决定局部化灾害的突发性阶段。(4)深入分析了条带开采局部化诱发灾害监测的基本内涵以及可监测性,系统地阐述了各个指标信息的监测与信息获取方法,构建了条带开采局部化灾害监测系统。(5)基于条带开采的煤柱局部化变形规律的物理相似模拟实验和三维有限差分数值计算,综合对比分析了围岩变形规律,覆岩与煤柱强度劣化特征,确定了合理的条带开采方案及其相关参数。(6)利用煤柱局部化松动变形与失稳范围的声波检测方法,定量确定了现场煤柱稳定参数范围。同时对现场地表变形进行监测与分析,为工程防灾减灾预警信息识别提供了可靠依据,最终确保了安全开采。本研究对同类矿区的安全开采具有积极有效的指导与借鉴意义。更多还原

【Abstract】 The deformation localization of the coal/rock is both an important characteristics of coal and destabilization precursor, which directly leads to reduce in its overall strength in the loading process and so as to deteriorate bearing-capacity of the project. It is one of a vital technology for safe mining to accurately predict localization destabilization of coal/rock. Essentially, in order to solve the technical difficulty, the localization destruction regularity of both coal pillars and the mining-induced localization destabilization would have been researched inevitably and development process of the excavation disturbance zone(EDZ) using trip mining in three underground. With the use of advanced monitoring methods, the multi-indicator information about localization destabilization had been reasonably determine and ultimately formed a valid method for localization hazard prediction and control in strip mining. This is a fundamental scientific problem in coal safe mining. Applied to theoretical analysis, characteristics upon acoustic emission(AE) testing of the physical and mechanical properties for coal/rock, AE-base physical simulation experiment, numerical simulation and field monitoring, the systematically analysis localization disasters caused due to the change of localization natural and disturbance conditions. Finally, a system of monitoring had been constructed and applied. Those will guide the practical production and ensures the safety in mining.(1) By investigation in field engineering, it indicates that both coal strip mining region and roof structure space variability exists in special coal region coal region. Certain natural or engineering conditions would lead to localization changes in the protective project and strength deterioration in localization areas, thus the evolution of project disaster induced by the project destabilization.(2) Applied acoustic emission experiment on localization damage and fracture in coal/rock, statistical analysis regularity of acoustic emission characteristics were finished at different stages of loading and breakdown in coal samples. At the same time, the loess’s physical indicators and collapsibility characteristic parameters experiments as well as the tri-axial test under the condition of consolidated/un-drained have been accomplished and obtained the loess’s statistical law of physical indicators, so as to further revealed the possibilities of localization instability and leading to localization disasters of rock mass and soil.(3) According to physical simulation and numerical calculation, the localization deformation process and evolution process induced by localization deformation in coal pillars in-depth were analyzed. Experimental result have shown that the process of the localization disaster caused by the destruction of individual coal pillars with defects mainly include three stages, i.e., the destruction stage of the coal pillar with defects., the stage of development of destruction in coal pillars, the stage of the sudden collapse. With the development of destruction in coal pillars, in case bedrock thickness is insufficient to support loose overburden weight, the roof fall or mine flood disaster may happen under the action of loose overburden. In addition, physical simulation experimental result shown that the strain soften process would reduce localization hazard due to individual disfigurement pillar. The principal assignment of prevention localization hazard is early discrimination to individual disfigurement pillar. Characterization of sandwich rock-mass is foundation to judge the pillar damage and development and caving height. The aquifer and its position in roof overburden is a evidence to estimate water hazard prone or not in the process of pillar damage.The one of the technical foundation is to optimize trip mining design so as to control localization hazard. The thickness of loose overburden rock-mass is crucial factor of sudden localization hazard.(4) Analysis of the content and the possibility of hazard induced by localization in strip mining at various depth, the methods of monitoring and acquisition information about various indicators have systematically formulated and built a local hazard monitoring system in strip mining.(5) Based on the physical simulation and numerical calculation according to three-dimensional finite-difference equation with the use of the law of localization deformation in coal pillars by strip mining, comprehensive contrast and analysis of the deformation laws of surrounding rock, strength deterioration characteristics in overburden and coal pillar, the reasonable program by strip-mining and its related parameters have been determined.(6) The utilization of acoustic detection method on localization loosen deformation and destabilization scope in coal pillars, the scale of stability parameters in coal pillars were defined quantitatively. At the same time, surface deformation monitoring and analysis on-site provided a valid basis for identifying the early warning information in project so as to ensure the safety mining ultimately.The research provides some attestation and reference to other safe mining.更多还原