大倾角煤层采动覆岩破断特征相似模拟实验研究

Similar Simulation Experimental Study on Fracture Characteristics of Overburden Strata under Mining with Large Dip Angle

煤层开采过程中,采动覆岩的破断特征是决定工作面矿压显现规律的关键因素.为掌握大倾角煤层覆岩在开采扰动下的破断和垮落演化机制,以库拜煤田铁列克矿区典型生产地质条件为基础,采用相似材料模拟实验的方法,分析仰采和俯采两种开挖方式条件下工作面覆岩的破断与垮落特征.结果表明:(1)仰采和俯采的基本顶初次破断方式不同,但断裂步距基本一致,分别为32.4 m、32.8 m.(2)仰采和俯采的平均周期破断步距分别为13.8 m、11.7 m,仰采的周期破断步距明显大于俯采.(3)由于受地层倾角影响,大倾角煤层基本顶岩层破断垮落后对采空区的充填普遍具有非均匀充实特点,采空区垮落岩石对悬露基本顶的非对称边界约束和不同开采方式的扰动差异共同导致了采动覆岩的差异化破断特征.

In the process of coal mining,the breaking characteristics of mining-induced overburden is the key factor that determine the law of mining pressure.In order to master the evolution mechanism of overburden and caving under mining disturbance,based on the typical production geological conditions in tirek mine area of kubai coal field,the model adopts the method of similar material simulation experiment to analyze the characteristics of overburden and caving under the conditions of overhead and underhand mining.The results show that:(1)The primary fracture modes of the basic roof of overhead and underhand mining are different,but the fracture steps are basically the same,which are respectively 32.4 m and 32.8 m.(2)The average periodic break step distance of the updraft and downdraft mining is 13.8 m and 11.7 m respectively,and the periodic break step distance of the updraft mining is significantly larger than that of downdraft mining.Conclusion:Due to the influence of stratum dip,the caving of the basic roof strata in the high-dip coal seam is generally characterized by uneven filling in the goaf.The asymmetric boundary constraints of caved rocks in the goaf on the overhanging basic roof and the disturbance difference of different mining methods lead to the difference of overburden fracture characteristics in the following mining.