含瓦斯煤岩围压卸荷瓦斯渗流及电荷感应试验研究

EXPERIMENTAL STUDY ON GAS PERMEABILITY AND CHARGE INDUCTION OF GASEOUS COAL ROCK UNDER CONFINING PRESSURE UNLOADING

煤岩卸荷过程物理信息监测对煤与瓦斯突出等动力灾害预测研究具有重要意义。应用自主研发的电荷采集装置,进行含瓦斯煤岩围压卸荷瓦斯渗流及电荷感应试验。研究结果表明:含瓦斯煤岩围压卸荷过程中,瓦斯渗流特性及电荷感应规律与煤岩的变形损伤过程具有十分密切的关系。随着围压卸荷速率的提高,煤岩内部大量微观裂纹扩展,促进煤岩变形损伤,增大煤岩内部裂纹间局部束缚电荷突变为自由电荷的概率,使得煤岩主破裂过程产生的感应电荷大幅增多;围压卸荷减弱了煤岩环向所受的限制作用,增加了煤岩内部新的导气通道,煤岩渗透率增大。气体携带煤粉颗粒与煤岩孔道固壁间的摩擦作用形成冲流电流,冲流电流对煤岩电荷信号贡献了附加量,使电荷信号增强。

Physical information monitoring is significant for the prediction of dynamic disasters such as coal and gas outburst under unloading. The gas permeability and charge induction experiments were carried out to the gaseous coal rock under the confining pressure unloading using the charge collection device developed. The gas permeability and charge induction were found to link closely to the deformation and damage of the gaseous coal rock in the process of confining pressure unloading. With the increase of the unloading rate,a large number of micro cracks were developed,which increases the probability of partial bound charge bacoming the free charge in the internal cracj s of coal rock. Consequently,the inductive charge had a significant increase in the main rupture pricess of coal rock. The confining pressure unloading weakened the circular restrictions of coal rock. New gas channels were produced inside the coal rock and led the permeability of coal rock to increase. The streaming current was formed by the friction action between the coal particles carried by gas and the hole wall of coal rock,which contributed an additional amount of the charge signal.