中高阶煤样承载过程裂隙演化及瓦斯渗透性变化对比

Comparison of gas permeability change and crack evolution in medium and high rank coal bearing processes

为了研究煤体承载过程中裂隙演化对瓦斯渗透率的控制作用,本文对两类煤样进行了力学、声发射和渗透性试验,结果如下:①在峰值前,煤样三个试验参数变化趋势较为一致,应变增量经历了减速、匀速和加速三个阶段,而声发射振铃数和渗透率变化趋势则经历了下降、稳定和上升三个阶段;②在峰值后,无烟煤的应变曲线下降较陡,未出现多个残余强度值,且声发射振铃数和渗透率数据在峰后测不到,而烟煤的应变曲线下降较缓,出现多个残余强度值,且声发射振铃数和渗透率还能够被监测到;③渗透率最大值都比初始渗透率高,无烟煤渗透率最大值在曲线的末端;而烟煤渗透率最大值与强度值点重合。煤样的裂隙演化对渗透率的变化具有关键控制作用,中硬煤的裂隙发育有助于瓦斯渗透。

In order to study the effect of crack evolution on gas permeability of coal during bearing process,mechanical,acoustic emission and permeability tests are carried out on two types of coal samples.The main conclusions are as follows:before the peak,the change trends of strain,acoustic emission ring number and permeability of coal samples are consistent.The coal strain increment experiences three stages:deceleration,homogenization and acceleration,while the change trend of acoustic emission ring number and permeability experiences three stages:decrease,stability and increase;after peak,there are great differences between anthracite and bituminous coal.The strain curves of the two anthracite with higher strength dropped steeply,and there are no multiple residual strength values,and the acoustic emission ringing number data and permeability data could not be measured after the peak.The strain curves of the two bituminous coal with lower strength decreases slightly,with multiple residual strength values,and the number of acoustic emission rings and permeability can also be monitored;the maximum permeability are all bigger than the initial permeability.The maximum permeability of two anthracite coal is at the end of the curve;the maximum permeability of the two bituminous coal is coincident with the strength value point,increasing the initial permeability.The evolution of coal crack plays a key role in controlling the change of permeability,and crack development of medium hard coal contributes to increasing gas permeability.