【作者】 张博；

【导师】 郝兵元； 王西林；

【作者基本信息】 太原理工大学 ， 资源与环境（专业学位）， 2023， 硕士

【摘要】 特厚煤层开采具有产量大、工效高和效益显著的优越性,对我国煤炭资源开发及煤炭行业发展起着重要作用。特厚煤层采出后形成大范围采空空间,引起上覆岩层断裂下沉幅度增大,造成较剧烈的矿山压力。合理的区段煤柱宽度能够对上覆岩层起到有效的支撑作用,达到隔离采空区和保障沿空巷道稳定性的优良效果。研究大倾角条件下煤层开采侧向应力分布规律、煤柱上覆岩层破断规律、煤柱合理宽度设计及沿空巷道围岩控制对实现大倾角煤层安全高效开采具有重要的指导意义。本文以孟家窑煤矿大倾角特厚煤层工作面为工程背景,从煤层顶底板岩层性质、相邻工作开采技术方法及矿压规律、回采过后基本顶岩层运动三方面进行研究:通过理论计算与数值模拟相结合的方法确定了适宜该煤层条件下的合理煤柱宽度;针对孟家窑煤矿上下工作面采掘衔接关系,分析了不同采掘阶段围岩控制的重点,提出了相应的围岩控制方案,并结合现场工业试验对围岩控制方案和煤柱宽度的合理性进行了验证。所研究推动了孟家窑煤矿倾斜特厚煤层沿空掘巷围岩稳定性控制的技术发展,可为相似地质条件下留设区段煤柱提供技术参考。主要研究内容如下:(1)通过对煤层顶底板进行钻孔取芯,并对所取岩芯进行岩石力学参数试验,得出顶底板岩层岩石物理力学参数,为后续开展数值模拟及围岩支护方案提供了数据基础。对相邻工作开采支架载荷数据进行分析,得出工作面开采初次来压布距及周期来压布距。(2)针对该煤层特有的地质条件,分析了煤层采出后覆岩空间破坏规律,基本顶破断后对覆岩的扰动及各种参数,建立倾斜煤层煤柱应力分析模型,推导出受上区段采空区侧向支撑压力影响下,煤柱内部屈服区宽度的计算公式。总结了煤柱宽度不同时,受到下区段回采扰动时顶板的破断规律。(3)结合“大、小结构”理论及“内、外应力场”理论,建立了倾斜煤层覆岩“大、小结构”力学模型,推导出低应力场范围计算公式,初步计算出了合理的煤柱宽度。(4)采用数值模拟方法对不同煤柱宽度条件下煤柱内部的应力、塑性区及沿空巷道围岩位移量的变化趋势进行分析,考虑经受下区段回采扰动时不同煤柱宽度的应力和塑性区变化趋势,综合确定煤柱宽度。分析了相同地质状况条件下不同埋深和不同采高时所需的合理煤柱宽度,总结出采高和埋深对煤柱宽度的影响趋势。(5)通过对实际采掘衔接关系的了解,建立采掘相向交锋数值模拟模型,分析出采掘相向交锋超前影响阶段和滞后影响阶段的距离。详细阐述了采掘不同阶段沿空巷道的承压来源,针对不同阶段的来压强度提出适宜不同阶段的围岩控制方案,对所提出的围岩支护方案进行数值模拟分析,结合工作面实测矿压数据验证了煤柱宽度和支护方案的合理性。更多还原

【Abstract】 The mining of extra-thick coal seam has the advantages of large output,high efficiency and remarkable benefit,which plays an important role in the development of coal resources and coal industry in China.After the extra-thick coal seam is mined out,a large range of goaf space is formed,which causes the increase of the fracture subsidence of the overlying strata and the severe mine pressure.Reasonable section coal pillar width can effectively support the overlying strata,achieve the excellent effect of isolating goaf and ensuring the stability of gob-side entry.It is of great guiding significance to study the lateral stress distribution law of coal seam mining,the fracture law of overlying strata of coal pillar,the reasonable width design of coal pillar and the surrounding rock control of gob-side entry under the condition of large dip angle to realize the safe and efficient mining of large dip angle coal seam.Based on the engineering background of the working face of the large dip angle and extra thick coal seam in Mengjiayao Coal Mine,this paper studies the properties of the roof and floor strata of the coal seam,the mining technology and the law of mine pressure,and the movement of the main roof strata after mining.Through the combination of theoretical calculation and numerical simulation,the reasonable coal pillar width under the condition of the coal seam is determined.Aiming at the mining connection relationship between the upper and lower working faces of Mengjiayao Coal Mine,the key points of surrounding rock control in different mining stages are analyzed,and the corresponding surrounding rock control scheme is put forward.The rationality of surrounding rock control scheme and coal pillar width is verified by field industrial test.The research has promoted the technical development of surrounding rock stability control of gob-side entry driving in Mengjiayao Coal Mine,and can provide technical reference for retaining section coal pillars under similar geological conditions.The main research contents are as follows:(1)Through the drilling and coring of the roof and floor of the coal seam,and the rock mechanics parameter test of the core,the physical and mechanical parameters of the rock strata of the roof and floor are obtained,which provides a data basis for the subsequent numerical simulation and surrounding rock support scheme.The load data of adjacent working mining support are analyzed,and the initial weighting distance and periodic weighting distance of working face mining are obtained.(2)According to the unique geological conditions of the coal seam,the spatial failure law of the overlying strata after the coal seam is mined,the disturbance of the overlying strata after the main roof is broken and various parameters are analyzed.The stress analysis model of the inclined coal pillar is established,and the calculation formula of the width of the yield zone inside the coal pillar under the influence of the lateral support pressure of the upper goaf is derived.The breaking law of roof under the disturbance of lower section mining is summarized when the width of coal pillar is different.(3)Based on the theory of ’ large and small structure ’ and the theory of ’ internal and external stress field ’,the mechanical model of ’ large and small structure ’ of inclined coal seam overburden is established,and the calculation formula of low stress field range is derived.(4)The numerical simulation method is used to analyze the variation trend of stress,plastic zone and surrounding rock displacement of gob-side entry under different coal pillar widths.Considering the variation trend of stress and plastic zone of different coal pillar widths under the disturbance of lower section mining,the coal pillar width is comprehensively determined.The reasonable coal pillar width required for different buried depths and different mining heights under the same geological conditions is analyzed,and the influence trend of mining height and buried depth on coal pillar width is summarized.(5)Based on the understanding of the actual mining connection relationship,a numerical simulation model of mining and excavation opposite intersection is established,and the distance between the advanced influence stage and the lagging influence stage of mining and excavation opposite intersection is analyzed.In this paper,the pressure source of roadway along goaf in different stages of mining is expounded in detail.According to the pressure intensity of different stages,the surrounding rock control scheme suitable for different stages is put forward.The numerical simulation analysis of the proposed surrounding rock support scheme is carried out.The rationality of coal pillar width and support scheme is verified by the measured mine pressure data of working face.更多还原