逆断层区域煤体应力分布规律

Coal stress distribution law in reverse fault area

逆断层区域地应力和构造应力叠加,煤体应力分布规律非常复杂,对逆断层区域煤层安全开采造成影响。为了掌握逆断层构造对煤体应力分布的影响,以贵州省新春煤矿1503回采工作面F4逆断层区域煤岩体为研究背景,采用FLAC数值模拟方法分析了逆断层区域煤体应力分布规律,建立了逆断层区域煤体应力分析数理模型,推导出煤体垂直应力和水平应力的计算表达式,并应用KYKY-2800B型扫描电子显微镜分别对距离逆断层70、40、10 m的煤样进行微观结构观测。研究结果表明:(1)逆断层区域100 m范围,随与逆断层距离减小,煤体的垂直应力和水平应力表现出先增大后减小的变化规律;(2)与逆断层越近,煤体稳定性越差,与逆断层距离小于12.74 m的范围内煤体将发生破坏,破坏后煤体强度发生劣化,应力降低;(3)距离逆断层70 m的K3煤样表面基本不存在裂隙,煤样较为完整;距离逆断层40 m的K2煤样表面存在“X”型裂隙,煤体未发生破坏仍处于弹性变形阶段,但K2煤样裂隙比K3多,煤样受力较大;距离逆断层10 m的K1煤样结构破碎、大小颗粒混杂,煤体发生破坏并处于塑性软化阶段或塑性流动阶段,煤体强度发生劣化,应力降低;(4)逆断层附近煤体破坏,导致应力降低,从而形成了与逆断层距离减小,煤体应力先增大后减小的分布特征。

The in-situ stress and tectonic stress in the reverse fault area are superimposed, and the distribution law of coal body stress is very complex, which affects the safe mining of coal seam in the reverse fault area. In order to obtain the effect of reverse fault structure on the stress distribution of coal mass, the coal-rock mass in F4 reverse fault area of No.1503 mining face of Xinchun Coal Mine in Guizhou Province was collected as the research background. FLACnumerical simulation method was used to analyze the stress distribution of coal mass in reverse fault area. The stress analysis theoretical model of coal body in reverse fault area was established, and the expression of coal body vertical stress and horizontal stress were derived. KYKY-2800 B scanning electron microscope was used to analyze the microstructure of coal samples at a distance of 70 m, 40 m and 10 m from the reverse fault. The research results show that:(1) within 100 m of the reverse fault area, the vertical stress and horizontal stress of the coal body increase and then decrease with the decrease of the distance from the reverse fault.(2) the stability of coal body is negatively related to the distance between coal body and reverse fault. The coal body would be destroyed within the range of less than 12.74 m from the reverse fault area. The strength of coal body deteriorates and the stress decreases.(3) there are basically no cracks on the surface of K3 coal samples 70 m away from the reverse fault, and the coal samples are relatively complete. The “X” type cracks are found on the surface of K2 coal samples 40 m away from the reverse fault, and the coal body is still in the elastic deformation stage without damage. The K1 coal sample with a fault of 10 m is broken in structure and mixed with large and small particles. The coal body is damaged and is in the stage of plastic softening or plastic flow. The strength of the coal body is deteriorated and the stress is reduced.(4) The damage of the coal body near the reverse fault leads to the reduction of stress, thus forming a distribution characteristic that the distance from the reverse fault decreases, and the stress of the coal body first increases and then decreases.