特厚煤层连续群组放煤方法初始顶煤放出规律研究

为了阐明特厚煤层群组放煤条件下初始顶煤的放出规律，采用理论分析和数值模拟的方法，研究了放煤口宽度对顶煤放出体形态特征、煤岩分界面演化以及两者空间关系的影响规律。结果表明，在顶煤厚度12 m条件下，随着放煤高度与放煤口宽度之比(δ值)的增大，放出体偏心率呈增大趋势，当δ值增大到一定程度后放出体偏心率逐渐趋向于一个稳定值。随着放煤口宽度的增大，单次顶煤放出量和放出效率均有显著提升，初始煤岩分界面影响范围不断增大，而其边界斜率呈降低趋势；放出体与煤岩分界面相切段的高度和范围不断增加，更有利于顶煤的充分放出，顶煤放出体与相邻煤岩分界面的相切特征可作为评估连续群组放煤顶煤放出效果的有效方法。

Top-coal initial caving law of continuous group caving method in extra-thick coal seams

In order to clarify the law of top coal caving with continuous group caving method in extra-thick coal seams, this study investigated the influences of the caving openings width on the morphological characteristics of caving body, the evolution law of the boundary of top coal and their spatial relationship based on the discrete element numerical simulation test and theoretical analysis.The results show that when the top coal thickness is 12 m, the increase of the ratio of coal caving height to caving width (δ) would cause the increase in the eccentricity of caving body.The eccentricity of caving body tends to have a steady value when the δ value increases to a certain value.In group coal caving, the increase of caving openings width would lead to higher single caving weight and caving efficiency with increasing influence range of the boundary of top coal increases and decreasing boundary slope.The length and height of tangent section between the initial boundary of top coal and the adjacent caving body increases continuously, which benefit top-coal recovery amount.The tangency between the top-coal caving body and the boundary of top coal of the previous adjacent caving group can be used as an effective method to evaluate continuous group caving.