倾斜煤层矿井突水对防水煤柱稳定性的影响规律分析

Influential stress of mining water outbursts on the stability of the waterproof coal pillar in the inclined coal seam

针对倾斜煤层防水煤柱合理尺寸留设问题,以道清煤矿淹井事故为原型,采用理论解析分析与数值计算相结合的对比分析方法,研究矿井突水对防水煤柱的稳定性影响,得到在矿山压力作用与水压作用下防水煤柱的极限设计尺寸优化公式,结合道清煤矿生产实际得到防水煤柱尺寸,通过数值模拟分析对比验证防水煤柱尺寸的合理性,并探究了防水煤柱的破裂过程。结果表明,煤体受采动应力影响,应力状态重新分布,煤体由弹性状态转变为塑性状态,产生塑性形变,强度逐渐降低,当压力增大达到其强度极限时,煤体内部出现裂纹,裂纹逐步扩展靠近防水煤柱,形成裂纹带,随着时间的累积,防水煤柱的强度逐渐降低,塑性变形区逐步向弹性核区移动,矿井涌水后,煤体裂隙导通充满大量孔隙水,在水压作用下,新生裂纹及原生裂纹进一步扩展,裂纹的张开度不断增大,最终形成导水裂纹带,使得防水煤柱发生严重破坏,煤体的破坏形式以拉剪破坏为主,煤层沿倾向发生相对位移,表现出剪涨变形,煤体出现剪切带。

Aiming at exploring the problem of rational sizes of the inclining water barrier,the paper takes it as its focus the study of the drowning accidents of Daoqing coal mine by using the contrastive analysis as the theoretical analysis and numerical calculation as the sampling model. When studying the impact of the mining water inrush on the stability of the waterproof coal pillar,we have managed to limit the design size in an optimal formula under the action of the mining pressure and the water pressure. Since the waterproof coal pillar has been built up from combining with the practice of the Daoqing Coal Mine,it is necessary to verify the proper size of the waterproof coal pillar size by comparing and calculating the numerical simulation results and the rupture process of the waterproof coal pillar. The results of our simulated investigation helps us to find that： the coal body has been influenced by the mining dynamic stress and the rock stress redistribution,for,when the coal body turns into plastic state from the elastic state,the plastic deformation would be resulted in,with the intensity of granite being gradually decreased. Furthermore,when the pressure has been increased to the limit of its strength,the coal body would be cracked,which may lead to the formation of the cracked zones with the waterproof coal pillar being extended step by step. At the same time,with the time going on,the strength of the waterproof coal pillar would be gradually declining,whereas the plastic deformation zone tends to be gradually turning to the elastic core area through a process of transition period. So far,large amount of pore water would be filled with the coal fracture under the effect of water pressure. Furthermore,as the new crack and the initial crack are getting to be enlarged,it would be possible for the water conducting crack zone to be evolved eventually,which is likely to increase with the increasing wider degree of the crack and in turn may lead to the serious damage of the waterproof coal pillar. Though the main damage form of the coal body is caused by the tensile shear failure,the relative displacement is likely to be induced with the increasing tendency of the coal seam,whereas the shear zone would occur in the coal body with the going on of the shear deformation.