煤炭开采对煤层底板变形破坏及渗透性的影响

煤层底板变形破坏除受地质因素控制外,还受开采因素影响。通过试验和理论分析,系统研究了煤炭开采对回采工作面底板应力、应变和破坏及渗透性的影响。研究结果表明,不同岩性岩石的渗透性在全应力-应变过程中为应变的函数,在微裂隙闭合和弹性变形阶段,岩石的原生孔隙和裂隙容易被压密,岩石的渗透率随应力的增加由大变小明显,当应力增大至极限强度时岩石试件破坏形成贯穿裂隙,岩石的渗透率迅速增大至最大,不同岩性岩石存在一定差异性;随着回采工作面推进,煤层底板岩层在横向上划分为原岩应力区、超前压力压缩区、采动矿压直接破坏区和底板岩体应力恢复区4个区。煤层底板岩体的渗透性随着煤炭开采底板岩体变形破坏而呈规律性变化。

Influence of coal mining on the deformation-failure and permeability of seam floor

Except the geological factors,the deformation and failure of seam floor are also controlled by mining factors.The influence of coal mining on stress-strain and permeability of seam floor in working face and its failure regularities were studied through theoretical analysis and the experiment.The research result shows that the permeability of the rock with different lithology is a function of strain in the process of complete stress-strain.In the micro-fracture closure and elastic deformation stage,the primary pores and cracks of rocks are easily compacted,it is obviously that rock permeability decreases with the increase of stress,when the stress intensity increases to the limit,the rock sample is destroyed and cracks through the sample are formed,,the rock permeability rapidly increases to the maximum.There are some differences between rocks with different lithology.With advancement of working face,the seam floor rocks are divided into four areas horizontally,they are initial stress area,advanced stress compression area,direct damaged area of mining stress and stress recovery area of floor rock mass.Permeability of seam floor rock shows regular variation with the deformation and failure of seam floor rock during coal mining.