浅埋煤层大采高工作面矿压规律及顶板结构研究

基于对榆神府矿区的大量实测分析,得出大采高工作面支架阻力随采高的增大呈现非线性增大,在采高增大到6 m后支架载荷迅速增大。支架动载系数随采高的变化不大,一般为1.4左右。工作面顶板来压步距随采高变化不大,初次来压步距35~70 m,周期来压步距9~20 m。顶板垮落带高度为采高的2~4倍,随采高的增大线性增大。工作面超前支承压力峰值随采高的增大略有降低,峰值位置与煤壁距离约为采高的2倍。根据现场实测和物理模拟分析,大采高工作面顶板形成"厚等效直接顶",使基本顶关键层铰接结构层位上移。根据直接顶充填条件,可分为充分充填型和一般充填型两类。针对常见的一般充填条件,提出了大采高工作面顶板的直接顶"短悬臂梁"结构和基本顶关键层"高位斜台阶岩梁"结构模型,给出了工作面额定支护阻力的计算公式,揭示了大采高工作面来压机理。最后,对理论计算公式进行了实例验证。

Roof weighting behavior and roof structure of large mining height longwall face in shallow coal seam

Based on a large amount of field observation in the Yushenfu mining area,the roof pressure at large mining height fully mechanized coal face in the shallow coal seam is obtained.The resistance of the large mining height face increases with the increase of mining height,and rapidly increases when the mining height is above 6 m.The dynamic load factor is 1.4 and has little change with mining height.The roof weighting steps are not changed with the mining height,and the first weighting step is 35-70 m,and the periodic weighting step is 9-20 m.The roof caving height is 2-4 times of the mining height.The peak abutment pressure decreases with the increase of mining height,and the peak position is about 2 times of mining height.According to the field observation and physical simulation,it is found that the large mining height causes high caving zone and “thick equivalent immediate roof” which leads to the hinge layer position of main roof structure move upward.According to the gob filling condition by caved immediate roof,the filling condition can be divided into sufficient filling type and general filling type.Based on the general filling condition which is more dangerous,the roof structural model of “high oblique step voussior beam” is proposed,and the calculation formula of the support rated resistance is put forward.Finally,the theoretical calculation formula of support rated resistance is verified.