山体赋存煤层群混合开采覆岩破断规律及顶板控制研究

发布时间：2019-03-03 18:54

【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。
[Abstract]:Under the condition of mining coal seam group in mountain body, the distribution characteristics of original rock stress affected by mountain body have important influence on the change degree and depth of original rock stress field, and on the mining design and roof control of mountain existing coal seam group. In addition, under the condition of mixed mining of coal seams, the multiple interaction of multi-seam mining is the key factor that affects the control of surrounding rock and the reasonable selection of supports in stope. Therefore, the failure and instability law of overlying rock under the mixed mining mode, the law of mining influence, the distribution of stress field and the law of distribution and evolution of overlying rock crack field are studied, and the control technology of surrounding rock stability in mining process of coal seam group is put forward. It is of great significance for the safe and efficient mining of coal seams. The numerical calculation of discrete element and the simulation experiment of similar materials show that the surface of Songhe Coal Mine is divided into three areas according to the influence degree of mountain body on stress distribution under the condition of mountain occurrence, that is, the obvious influence area within 100 m from the surface. The weakened area from the surface 100m~250m and the non-affected area below 250 m from the surface; The depth of 3 # coal seam is about 400 m, which is outside the influence area of mountain body; In the process of mixed mining of coal seams, the failure and instability of overburden rock and the failure degree of floor are not affected by the adjacent coal seam mining in 3 and 9 # coal seam mining. The behavior of mine pressure is characterized by the appearance of single coal seam mining pressure, while the mining pressure of 4? The 6 # coal seam mining is affected by the movement of surrounding rock after 3 # and 9 # coal seam mining, respectively. Based on fractal geometry theory, the failure degree of roof and floor after mining in different coal seams under mixed mining conditions is quantitatively analyzed. The results show that the ratio of fracture to mining increases with the increase of the composite thickness of the coal seam and is influenced by the interval between the coal layers. The fractal dimension of coalbed roof fractures is affected by the thickness of coal seam, the spacing of coal layers and the lithology of overlying strata, and the fractal dimension of cracks increases with the increase of the thickness of coal seam composite seam. Based on the analysis of fractal dimension of cracks after coal seam mining, it is concluded that the mining of 6 # coal seam is greatly affected by the mining of adjacent coal seam, and the control of top and floor of working face should be strengthened. Based on the existing conditions of coal seams in Songhe Coal Mine, the numerical calculation of discrete element shows that the roof support design of working face can be designed by conventional support when mining in coal seam 3 and 9. In 4 # coal seam mining, the key point of supporting design is to control the broken roof of the working face, and the key point of the supporting design of the face is to strengthen the control of the broken roof and floor in the mining of 6 # coal seam. According to the stability of surrounding rock and the characteristics of overlying rock structure and the interaction between support and surrounding rock under the condition of mixed mining in coal seams, a mechanical model of interaction between support and surrounding rock in upstream and downward mining is established. The method to determine the parameters of support is put forward. According to the characteristics of rock pressure behavior in coal face No. 3 and the determination method of face support resistance, the supporting roof of ZY6400/16/ 34 masked hydraulic support is determined. The average thickness of 9 # coal seam is between 1.2m~1.5m, and ZY4800/09/ 21 hydraulic support is selected to support roof. The results show that the average value of the end resistance of the support is 4446KN and the average value of the time weighted resistance is 3904KN, which is in good agreement with the theoretical calculation, and the support has good adaptability. The safe mining of No. 3 coal seam is guaranteed.
【学位授予单位】：中国矿业大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TD325;TD327.2

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