论文部分内容阅读
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 order to study the stress distribution and deformation law of the coal around the drainage borehole, the mechanical properties of the coal around the borehole were analyzed and a viscoelastic-plastic model considering the plastic softening and expansion behavior of coal was established. The stress, Displacement, pore diameter and pressure relief range, the stress distribution and pressure relief effect of the borehole in soft and hard coal seam were compared and analyzed. The variation of borehole diameter of drainage borehole was studied and the rapid decay of the volume fraction of borehole drainage in soft coal seam was explained s reason. The results show that the coal around the borehole has plastic softening, expansion and rheological properties. The soft coal seam has better pressure relief effect, and the creep deformation is more severe. It may cause instability damage and blockage in a short time Gas drainage channels, resulting in the rapid decline in gas drainage volume fraction; although the diameter of the hard seam drilled hole is still in a stable state, does not occur blocking phenomenon, but to the depth of the mine due to increased stress creep deformation intensified, It is possible destabilization damage. The research results and production practices have good consistency, which can provide theoretical guidance for the determination of gas drainage parameters.