【作者】 胡永忠；

【导师】 刘长友；

【作者基本信息】 中国矿业大学 ， 采矿工程， 2015， 博士

【摘要】 山体赋存煤层群开采条件下,受山体影响的原岩应力的分布特点、对原岩应力场的变化影响程度及深度,对于山体赋存煤层群的开采设计、顶板控制等具有重要的影响。此外,在煤层群混合开采条件下,多煤层开采的多重相互影响,是影响采场围岩控制、支架合理选型的关键因素。因此,研究混合开采方式下覆岩破断失稳规律、采动影响规律、应力场分布规律和覆岩裂隙场分布演化规律,提出煤层群开采过程中围岩稳定性的控制技术,对于煤层群的安全高效开采具有重要意义。采用离散元数值计算和相似材料模拟试验研究表明,松河煤矿地表在山体赋存条件下,依据山体对应力分布变化的影响程度分为三个区,即距地表100m以内的明显影响区、距地表100m~250m的影响减弱区和距地表250m以下的无影响区;3#煤层赋存深度约为400m,处于山体影响区域之外;煤层群混合开采过程中,3#、9#煤层开采覆岩破断失稳以及底板破坏程度不受临近煤层开采的影响,矿山压力显现表现为单一煤层开采矿压显现特点,而4#、6#煤层开采分别受到3#、9#煤层开采后的围岩运动的影响。采用分形几何理论,对混合开采条件下各煤层开采后顶底板破坏程度进行定量分析。研究表明,各煤层开采后的裂采比随着其下煤层的复合厚度的增大而增大,并受到煤层层间距的影响;煤层顶板裂隙的分形维数受到煤层厚度、煤层层间距、上覆岩层岩性等的影响,且随煤层复合煤层厚度的增大,裂隙的分形维数增大;通过对煤层开采后裂隙分形维数进行分析,得出4#、6#煤层的开采受临近煤层开采后的影响较大,应加强工作面顶底板的控制。基于松河煤矿煤层群赋存条件,采用离散元数值计算研究表明,3#、9#煤层开采时,工作面顶板支护设计可采用常规支护设计;4#煤层开采时,支护设计的重点是对工作面破碎顶板的控制;6#煤层开采时,工作面支护设计的重点是加强对破碎顶底板控制。根据煤层群混合开采条件下围岩的稳定性状况和覆岩结构特征,以及支架与围岩的相互作用特点,建立了上行、下行开采时支架与围岩相互作用力学模型,提出了支架支护参数的确定方法。根据3#煤层工作面矿压显现特征与工作面支架阻力的确定方法,确定了ZY6400/16/34型掩护式液压支架支护顶板;4#、6#、9#煤层平均厚度在1.2m~1.5m之间,确定选用ZY4800/09/21型液压支架支护顶板。通过现场实测3#煤层开采过程中工作面矿压显现规律可知,支架循环末阻力平均值为4446KN,时间加权阻力平均值为3904KN,和理论计算较吻合,支架具有良好的适应性,保障了3#煤层的安全开采。更多还原

【Abstract】 Distribution characteristics and the effects changes of original rock stress influenced by mountain topography have an important influence to the coal seam group mining design, roof control etc.The key influencing factor of surrounding rock control and reasonable selection of support in the coal seam group mixed mining conditions is multiple interaction of coal seam mixed mining.That the research on characteristics of overlying strata breaking, influence characteristics of mining, distribution of formation stress field and fissure field evolution characteristics of overlying rock had an important significance for the safe and efficient mining of coal seam group mixed mining.Discrete element numerical calculation and similar material simulation experiment are used to research on this subject according to the mountain occurrence surface condition.Studies suggest that rock stratum under mountains can be divided into significantly effect area(distance to surface less than 100m), effect decreased area(distance to surface 100m~250m) and no effect area(distance to surface more than 250m). 3# coal seam depth is about 400 m which is outside of the influence of mountain.The presentation of the 3# and 9# coal mining pressure manifestation to show the characteristics of single seam mining pressure,which is because the overlying rock breaking instability and floor damage extent are not affected by adjacent coal seam mining.While, the 4# and 6# coal mining are respectively effected by the surrounding rock movement of the 3# and 9# coal mining.Fractal geometry theory was used to quantitatively descript the roof and floor damage degree after each coal seam mining of coal seam group mixed mining.Studies show that, the crack-production ratio increased with the increase of lower coal seam composite thickness after each coal seam mining, which impact by coal layers spacing; Seam thickness, coal layer spacing and the overlying rock lithology had affect the fractal dimension of seam roof fractured,and the fractal dimension of fracture increased with the increase of composite seam thickness;The 4 #, 6 # coal seam mining greatly influenced by near coal mining have got and it should strengthen the control of working face roof and floor by analyzed fractured fractal dimension after coal mining.Based on Songhe Coal Mine seam group occurrence conditions, the discrete element numerical studies show that working face roof support design can use conventional support design when 3 # 、9 # coal seam mining; that support design should focus on broken roof control when 4 # coal seam mining; that support design should focus on strengthen broken roof and floor control when 6 # coal seam mining.According to the surrounding rock stability,the overlying rock structural characteristics under conditions of coal seam group mixed mining and characteristics of the interaction between the stent and the surrounding rock,the mechanics model between the support and the surrounding rock of ascending mining and descending mining is established, and the method of support parameters is determined. ZY6400/16/34 type shield hydraulic is select to support the roof based on 3 # coal seam face behavior characteristics and support resistance determination method. ZY4800 / 09/21 type hydraulic is select to support the roof based on the fact that 4 #、6 #、9 # coal seam average thickness is between 1.2m~1.5m.By the face strata behavior regularity field measurement that in the process of 3# coal seam mining shows that the stent average resistance of the end cycle is 4446 KN,the average of time-weighted resistance is 3904 KN, which is agree well with theoretical calculations.The stent has a good adaptability to protect the 3 # coal seam safe mining.更多还原