考虑流变特性的抽放钻孔应力分布和移动变形规律研究  

Stress distribution and movement law around drainage borehole when considering rheological property

作　　者：郝富昌[1,2] 支光辉[1] 孙丽娟[2] 

机构地区：[1]河南理工大学河南省瓦斯地质与瓦斯治理重点实验室-省部共建国家重点实验室培育基地,河南焦作454000 [2]中国矿业大学(北京)资源与安全工程学院,北京100083

出　　处：《采矿与安全工程学报》2013年第3期449-455,共7页Journal of Mining & Safety Engineering

基　　金：国家"十二五"科技支撑计划项目(2012BAK09B02-1);国家重点基础研究发展计划(973)项目(2005CB221501)

摘　　要：为了研究抽放钻孔周围煤体的应力分布及移动变形规律,分析了钻孔周围煤体的力学特性,建立了考虑煤的塑性软化和扩容特性的黏弹塑性模型,得到了煤体应力、位移、孔径变化和卸压范围的表达式,对比分析了软硬煤层钻孔的应力分布及卸压效果,研究了抽放钻孔孔径变化规律,解释了软煤层钻孔抽放体积分数快速衰减的原因。研究结果表明:钻孔周围煤体具有塑性软化、扩容和流变特性,软煤层钻孔具有更好的卸压效果,蠕变变形更为剧烈,在短时间内就可能发生失稳破坏,阻塞瓦斯抽放的通道,致使瓦斯抽采体积分数迅速下降;硬煤层钻孔直径虽有缩小但仍处于稳定状态,并不发生堵孔现象,但是到井田深部由于应力增大,蠕变变形加剧,就有可能发生失稳破坏。研究成果与生产实践具有较好的一致性,可以为瓦斯抽采参数的确定提供理论指导。In this paper, to investigate the stress distribution and movement law around gas drainage boreholes, the mechanical properties of coal mass around boreholes were analyzed, a visco-elastic plas- tic model considering the plastic softening and dilatancy was established, and the expressions of coal stress, displacement, pore size variation and pressure-relief range were obtained. In addition, the stress distributions and pressure-relief effects around drainage boreholes in the hard and soft coal seams were comparatively analyzed, the pore size variation rules of boreholes were studied, and the reason about rapid decay of borehole drainage concentration in soft seam was explained. The results show that the coal mass around boleholes have the properties of plastic softening, dilatancy and rheological. The boreholes in soft coal seam can get better pressure-relief effect, the creep deformation is more severely,and the unstabe failure can occur in a short time, which will block the gas drainage channel, and result in rapid decline of gas drainage concentration. Meanwhile, the pore sizes of boreholes in hard coal seam are reduced somewhat, but still in stable state, and will not block the gas drainage channel. But, with the increase of ground pressure in deep minefield, the creep deformation will increase, and the unstabe fail- ure may occur. The research results agree well with mining practice, which can provide theoretical guidance for the determination of gas drainage parameters.

关 键 词：抽放钻孔 流变特性 应力分布 移动变形 塑性软化 扩容 软硬煤 

分 类 号：TD713.1[矿业工程—矿井通风与安全]