缓倾斜中厚煤层采动应力场时空演化及覆岩破裂规律

发布时间：2018-03-23 19:22

本文选题：缓倾斜　切入点：中厚煤层　出处：《重庆大学》2015年硕士论文

【摘要】：进入21世纪,随着我国新一轮经济结构的布局与发展,煤炭资源在国民经济中依旧占有较高的比重。其中煤矿开采中的地层应力变化及安全开采已越来越受到人们的关注。煤矿开采过程中,巷道的掘进及工作面的回采,都会使得煤层围岩应力场重新分布。采场围岩的应力受采动影响,原有应力平衡被破坏,巷道围岩的结构及承载能力受到一定的影响,某些应力集中区还会造成围岩的变形失稳、甚至出现煤岩体的破碎、岩爆及突出,直接影响煤炭的正常生产。因此,采动应力场的监测、控制及研究,逐渐成为与煤炭开采并存的问题之一,受到人们的普遍关注。本文以川煤集团白皎煤矿为背景,研究了该矿缓倾斜煤层开采过程中回采巷道围岩应力场的时空演化规律,并对覆岩破裂规律进行了分析,为工作面的安全高效开采提供了一定的理论依据和技术支持。本文运用有限差分软件FLAC3D,对缓倾斜中厚煤层的开采过程进行模拟,分析了不同采距下采场围岩的应力位移变化,研究了采动应力场的时空演化规律深入探讨了覆岩破断移动变形规律。论文的主要工作和取得的研究成果如下:①在前人研究成果的基础上,从理论上对缓倾斜中厚煤层开采后的煤岩体应力、垮落形态、破坏裂隙扩展等机理进行分析。并系统研究了采场覆岩“三带”的分布及影响高度、范围的确定;分析了覆岩破断的应力学模型;对裂隙场的空间形态进行理论描述。②将现场钻取的岩石样本进行加工,制作成实验室标准试件,通过岩石力学性质试验得到试件的一般抗压强度为39.13MPa;通过Mohr极限应力圆理论及岩石破断角θ计算得出三组试件的参数黏聚力c,取平均值为7.95MPa。结合室内物理力学性质试验及白皎矿地质情况得出煤系地层的物理力学特性,为数值模拟提供材料参数支持。③运用有限差分软件FLAC3D对缓斜中厚煤层开采进行数值模拟,结果表明:应力场受采动影响而变化,采面推进50m时,上山保护煤柱附近围岩最大垂向应力达到50.33MPa;回采150m时垂向应力增大为66.58MPa,与采面未开挖前初始应力18.24MPa比较,增大了48.34MPa,顶板最大下沉量达20.30cm。该处现场实测最大位移下沉量为24.80cm,模拟结果与现场测量值较吻合。④对围岩应力现场监测数据和数值模拟结果进行对比分析,随着工作面的推进,对固定监测点的影响越来越明显,垂直应力逐渐变大、且应力变化速率随开挖距离的接近而逐渐加快;顶板覆岩及底板岩层的移动变形逐渐增大。
[Abstract]:In the 21st century, with the layout and development of China's new economic structure, The coal resources still occupy a high proportion in the national economy. The change of stratum stress and safe mining in coal mining have been paid more and more attention. In the process of coal mining, the tunneling of roadway and the mining of working face are paid more and more attention. The stress of surrounding rock of stope is affected by mining movement, the original stress balance is destroyed, and the structure and bearing capacity of roadway surrounding rock are affected to some extent. Some stress concentration areas will cause the deformation and instability of surrounding rock, even the breakage of coal and rock mass, rock burst and outburst, which will directly affect the normal production of coal. Therefore, the monitoring, control and study of mining stress field, This paper, taking Baijiao Coal Mine of Sichuan Coal Group as background, studies the time and space evolution law of surrounding rock stress field of roadway in the mining process of slowly inclined coal seam. The fracture law of overburden rock is analyzed, which provides certain theoretical basis and technical support for safe and efficient mining of coal face. In this paper, the mining process of gently inclined medium thick coal seam is simulated by using finite-difference software FLAC3D. The variation of stress and displacement in surrounding rock of stope under different mining distances is analyzed. In this paper, the temporal and spatial evolution of mining stress field is studied, and the deformation law of overburden fracture movement is deeply discussed. The main work and the research results obtained in this paper are as follows: 1. Based on the previous research results, This paper theoretically analyzes the mechanism of coal and rock mass stress, collapse form and fracture expansion after mining of gently inclined medium thick coal seam, and systematically studies the distribution of "three zones" of overburden rock in stope and the determination of influence height and range. The stress model of overburden rock fracture is analyzed, and the space shape of fracture field is described theoretically. The general compressive strength of the specimen is 39.13 MPA through rock mechanical property test, and the cohesion force of three groups of specimens is calculated by Mohr limit stress circle theory and rock fracture angle 胃, the average value is 7.95 MPa, combined with indoor physical mechanics. The physical and mechanical properties of coal measure strata are obtained by qualitative tests and geological conditions of Baijiao Mine. To provide material parameter support for numerical simulation, using finite difference software FLAC3D to simulate mining of gently inclined medium thick coal seam. The results show that the stress field changes under the influence of mining movement, and the mining face advances 50 m. The maximum vertical stress of surrounding rock near the coal pillar is 50.33 MPA, and the vertical stress increases to 66.58 MPA at 150 m after mining, which is compared with the initial stress 18.24MPa before the mining face is not excavated. The maximum subsidence of roof is increased to 20.30 cm, and the measured maximum displacement is 24.80 cm. The simulation results are in good agreement with the measured values. 4. The field monitoring data and numerical simulation results of surrounding rock stress are compared and analyzed with the advance of the working face. The effect on the fixed monitoring points is more and more obvious, the vertical stress becomes larger, and the change rate of the stress increases with the distance of excavation, and the moving deformation of the roof overburden and the bottom rock layer increases gradually.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TD823.252;TD31

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