【作者】 杨威；

【导师】 林柏泉；

【作者基本信息】 中国矿业大学 ， 安全技术及工程， 2013， 博士

【摘要】 瓦斯是煤矿安全生产的主要灾害源，开采保护层是高瓦斯突出煤层群区域瓦斯治理最有效的技术，但保护层开采过程中采场力学行为演化特征及其对瓦斯三维流动影响机制缺乏系统的理论研究，尤其是薄上保护层采高小、通风排放瓦斯能力差、卸压范围小，区域瓦斯治理盲目性大。该论文采用理论分析、数值模拟和现场测试相结合的研究方法，以三向应力对瓦斯三维流动及突出危险性的影响机制为基础，以薄上保护层为研究对象，以采场三向应力场时空演化规律为主线，建立了采场空间分布模型，构建了煤层群安全高效开采模式，破解了近距离煤层群卸压瓦斯治理难和远距离煤层群卸压难等技术难题。主要创新成果如下：统计分析了原岩应力分布特征，指出最大和最小应力倾向于沿水平方向，中间应力倾向于沿纵向，且最大应力为最小应力2倍以上；发现了最大应力方向是控制煤层巷道掘进突出危险性的关键因素，将防治煤与瓦斯突出理念推至新的高度。研究发现：在同一应力场下，当巷道沿垂直于最大应力方向掘进时，掘进头前方产生显著的应力集中，突出危险性较大；而当巷道沿最大应力方向掘进时，掘进头前方无应力集中，突出危险性较小。同时发现，煤层强度差异是导致局部应力集中的关键因素，当巷道从一种强度的煤体掘向另一种强度的煤体时，不论巷道沿何种方向掘进，突出危险性都较大。通过分析采场围岩破坏特征，建立了适用于峰前阶段的“应力-裂隙-渗透率”本构模型，并采用数值模拟和现场试验相验证的方法，研究了采场三向应力分布及其对瓦斯三维流动的控制作用，同时研究得出了超前支撑压力、卸压角、“O”形圈等随煤层开采的时空演化机制，在此基础上提出了下覆围岩“三带五区”划分和采场“四层空间”分布模型，最终首次从力学角度进行远近距离煤层群划分。现场测试了近距离煤层群薄上保护层采场瓦斯流动富集规律，验证了采场划分理论模型的正确性，并针对其特点发明了采动区强扰动瓦斯抽采钻孔护孔技术和“三位立体”分源瓦斯治理技术，提高了钻孔抗采动破坏能力，实现了区域瓦斯分源协同抽采，防治瓦斯超限。开创了基于最大应力方向的区域防突设计新方法，并得到现场试验的验证。根据最大应力方向对煤巷突出危险性的控制机理，通过将突出煤巷沿平行于最大应力方向布置，避免掘进头应力集中，降低突出危险性，该技术为除开采保护层和区域瓦斯预抽之外的另一种新的区域瓦斯治理技术。主要研究成果体现在以第一作者发表学术论文11篇，其中被SCI收录3篇，EI收录5篇，ISTP收录1篇，授权发明专利12项，主体内容获得陕西省、中国煤炭工业协会等科技进步一等奖6项。研究结果为高瓦斯煤层群保护层开采区域瓦斯治理奠定了重要理论和技术基础，对今后矿井瓦斯治理和防突设计有着重要的理论意义和现实价值。更多还原

【Abstract】 Mining protective coal seam is the most efficient method for regional gas controlunder the condition of coal seam group. But the mechanical behavior evolutioncharacteristics of the stope and the influence mechanism on gas three dimensionalflow had no system theoretically studies all the time, especially the thin protectivecoal seam, which makes the regional gas control to be lack of guidance. Thedissertation studied how the three dimensional stress affects the three dimensional gasflow and the outburst riks by the method of numerical simulation, field experimentand theoretical analysis. The dissertation also built the spatial distribution model ofthe stope and divided the coal seam group to be far and close coal seam groups bystudying the three dimensional stress evolution with space and time of mining theupper thin protective coal seam. At last the efficient exploitation mode of coal seamgroup was built, and the problem of gas control under close coal seam group and theproblem of stress relief under far coal seam group were solved. The main conclusionsare as follows:The statistical analysis of in-situ stress distribution characteristics pointed outthat the maximum and minimum principal stresses are tend to be along the horizontaldirection, the intermediate principal stress is tend to be along the longitudinaldirection, and the maximum principal stress is2times of the minimum principal stress.It was found that the direction of the maximum stress is the key factor to control theoutburst risk when driving a roadway in an outburst risk coal seam, which highlightsthe coal and gas outburst prevention concept to a new heights. The study found thatsignificant stress concentration appears in front of the roadway face when the drivingroadway is perpendicular to the direction of the maximum stress, while there is nostress concentration in front of the roadway face when the roadway drives along thedirection of the maximum stress. The outburst risk is much higher when the roadwayis perpendicular to the maximum stress than parallel to. It was also found that thedifference of coal seam strength is the key factor to generate stress concentration, theoutburst are higher when the roadway drives from one strength coal seam to anotherno matter what direction the roadway drive along.The “stress-fracture–permeability” constitutive model was established for theformer stress peak stage, and then the three dimensional stresses differences of thestope surrounding rock mass and how they control the gas three-dimensional flow atdifferent positions was studied by the numerical simulation and field experiment. At the same time, the space time evolution mechanism of the abutment stress, pressurerelief angle, O-shaped stress relief area during the thin coal seam mining process wereinvestigate. Then the rock mass under the mined coal seam was divided into threebelts and five zones, and the stope surrounding rock mass was divided into fourspaces. At last the coal seam group was firstly divided into far and near groups fromthe perspective of mechanics, which is the theoretical basis for regional gas control ofthe coal group.The gas flow characteristics of mining the upper thin coal seam under close coalseam condition was investigated, which proved the stope division to be crrect. Inorder to prevent the pressure relief gas of the close coal seam group from flowing intothe thin coal seam and cause the gas overrun, the gas drainage hole sealing technologyfor strong disturbed mining area and gas three dimensional drainage technology areinvented according to the stope surrounding rock mass migration and gas flowenrichment regularity. The technologies enhanced the drilling damage resistanceability and efficiently control the relieved gas of the closed coal seam group.A new technology of regional gas control was initiated based on the stressdirection. Most of the roadway should be designed parallel to the direction of themaximum stress in order to reduce the stress concentration and then reduce theoutburst risk, which was proofed to be right by the field experiment. The technologyis a new regional gas control technology beside the two technologies of protectivecoal seam and regional gas pre-drainage.The main results published3papers in SCI journals,5papers in EI journals and1journal in ISTP journals, authorized12patents, and6first prizes about progress ofscience and technology including the Shaanxi Province, China Coal IndustryAssociation.The results lay an important foundation of theory and technology for gas controlwhen mining the protective coal seam, and have the important theory significance andpractical value for future mine gas control and prevention design.更多还原