软弱薄基岩放顶煤安全开采关键问题研究

Key problems of safety mining in caving coal with weak thin bedrock

采动裂隙发育规律和支架荷载变化规律是软弱薄基岩放顶煤安全开采的两个关键问题,以淮北朱仙庄煤矿薄基岩区综放工作面为研究对象,采用物理模拟、理论分析、现场实测等方法对这两个问题进行了深入研究。研究结果表明：软弱薄基岩中的黏土质矿物较多,在地下水的长期作用下,极易发生风化崩解、膨胀,有效地阻隔了采动裂隙的发育,放顶煤开采时裂采比为3.6~5.4,裂隙带发育高度远远小于正常厚度基岩,且基岩越薄,裂隙发育高度受阻现象越明显;薄基岩在风化作用下,力学性质大大弱化,煤层顶板中无基本顶承载层,支架工作阻力远远小于额定工作阻力,来压步距远小于正常基岩,来压显现不明显。

The two key issues concerning safety mining in caving coal with weak thin bedrock are the development law of mining-induced fissure and variation regulation of support load. This paper uses physics simulation, theoretical analysis and field measurement to further research the two problems centered on the fully-mechanized caving face in thin bedrock area of Zhuxianzhuang coal mine. The re- sult shows that weak thin bedrock is rich in clay minerals. The bedrock is liable to disintegrate and ex- pand because of weathering under the chronicle impact of groundwater, effectively resisting the devel- opment of mining-induced fissure. The fissure-mining ratio in the top coal caving ranges from 3.6 to 5.4 The crack developing height of the breakage is much less than the normal thickness of the bedrock, and the thinner the bedrock is, the more obviously resisted the height of the fractured zone is. The bedrock＇s mechanical property will be greatly weakened under the weathering. Without basic roof bearing layer in the roof, the working resistance of support is much less than the rated working resistance. The roof weighting step is far less than that of normal bedrock, and therefore the phenomenon of weighting is not obvious.