厚松散层薄基岩综放开采覆岩破断机理研究

摘要

Based on the methods of numerical simulation, theoretical analysis, field measurement and so on, the break- age mechanism of overlying strata of uhrathin bedrock and thick coal seam and mining-induced development were studied. The results indicate that with the weathering, mechanical property of ultrathin bedrock substantially reduces, there are key overburden in coal roof, stress arch is in dynamical balance by mining, and apsidal angle is located in gangue of worked out section and coal wall in front of working face, underground pressure of working face is not obvi- ous with the influence of stress arch; stress arch prevents the growth of the fracture during mining, the growth of the fracture during mining depends on the final height of the stress arch, fracture grows quickly and closes easily, although the height is gigantic, valid water-guiding erack does not grow high finally. The research result properly explains the phenomenon of big static pressure, little dynamic pressure,little coefficient of live load, insufficieney of fracture grow- ing and so on under conditions of fully-meehanized top-coal caving mining with ultrathin bedrock and thick coal seam, made safe and efficient production come true under conditions of fully-mechanized top-coal caving mining with ultra- thin bedrock and thick coal seam.%采用数值模拟、理论分析、现场实测等方法对厚松散层超薄基岩厚煤层综放开采覆岩的破断机理以及对采动裂隙发育的影响进行了深入研究。研究结果表明：超薄基岩在风化作用下,力学性质大幅度降低,煤层顶板中无基本顶关键层,工作面推进过程中形成动态平衡的应力拱,拱脚分别位于采空区稳定矸石上和工作面前方煤壁内,在应力拱的作用下,工作面矿压显现不明显;应力拱阻止了采动裂隙的发育,应力拱最终发育高度决定了采动裂隙的发育高度,采动裂隙在风化基岩中发育速度快,也极易闭合,虽然采厚较大,但最终有效导水裂隙带发育不高。研究结果合理解释了厚松散层超薄基岩综放开采静压大、动压小,动载系数小、采动裂隙发育不充分等现象,实现了超薄基岩下厚煤层综放开采安全高效生产。