多放煤口综放开采起始放煤顶煤时空场耦合分析

Coupling analysis of top coal space-time field in initial coal caving with top coal caving mining group

为了改善综放开采顶煤放出效果,提高顶煤放出率、降低含矸率,改进群组架间配合方式、优化放煤工艺参数,采用理论分析和GDEM离散元数值模拟分析相结合的方法,研究破碎散体顶煤放出体的发育形态及群组—起始放煤放出体的发育过程、顶煤运移轨迹、煤矸分界面下沉动态特征、顶煤放出影响范围和顶煤放出时空场的耦合关系。研究结果表明:顶煤放出体发育是由放煤口向煤矸分界面呈近似环状的过程,顶煤也呈近似环状松动放出;顶煤放出体发育体积随放煤口尺寸增大而增大,且经历“竖向椭圆形-类圆形-横向椭圆形”3个阶段,其中放出体发育宽度与同时放煤支架数满足三次函数关系。顶煤是沿着最小阻力路径以近似直线向放煤口移动放出的,且放煤口中心垂线附近顶煤模型颗粒优先到达放煤口,运移轨迹整体关于放煤口中心垂线对称;顶煤放出影响范围及位移随放煤口尺寸的增大而增大。煤矸分界面下沉动态曲线最低点位移和速度与放煤时间呈正相关;下沉动态曲线达到稳定所需时间与同时放煤架数呈负相关;煤矸分界面曲线整体近似为水平翻转的正态分布曲线,并关于放煤口中心垂线对称。研究对放顶煤开采有一定借鉴意义。

In order to improve the effect of top coal caving in fully-mechanized top coal caving mining,improve the coordination mode between the subracks.optimize the coal mining process parameters and improve the coal caving rate and reduce the gangue content,the theory analysis and GDEM discrete element numerical simulation analysis method were combined to study the developmental morphology and group of fractured top coal release body-development process of initial coal release,top coal migration trajectory curve,coal sagging interface sinking dynamic curve characteristics,top coal release influence range and the coupling relationship between time and space.In this paper,the simultaneous coal injection of different combinations of the adjacent supports in the direction of the working face is referred as group coal caving.The results show that the development of top coal release is a nearly circular development process from the coal release to the coal gangue interface.and the top coal release also shows an approximate annular loose release;the development volume of the top coal outlet increases with the increase of the size of the coal discharge outlet,and it experiences three transitional stages of“vertical elliptic-quasi-circular-transverse elliptic”,in which the development width of the outlet meets the cubic function relation with the number of the simultaneous coal-supporting stents.Top coal release is a process of moving out along the path of minimum resistance in an approximate straight line,and the top coal model particles near the vertical line of the center of the coal release have priority to reach the coal release,and the migration path is symmetrical with the vertical line of the center of the coal release;the influence range and displacement of top coal release increases with the increase of coal inlet size.The displacement and velocity at the lowest point of the subsidence dynamic curve of coal gangue interface are positively correlated with the time of coal caving,there is a negative correlation between the time needed for the subsidence dynamic curve to reach stability and the number of simultaneous coal drawing racks,the coal gangue interface curve is approximately the normal distribution curve of horizontal inversion,and it is symmetrical about the vertical line of the center of coal hole.Research has certnin reference significance for top coal caving mining.