含瓦斯煤岩卸围压声发射特性及能量特征分析

Analysis of characteristics of acoustic emission and energy of of gas-bearing coal during unloading confining pressure

利用自主研发的含瓦斯煤岩热流固耦合三轴伺服渗流装置配合声发射监测系统对不同围压作用下含瓦斯煤岩进行了卸围压试验,试验结果表明:不同围压作用下含瓦斯煤岩声发射事件率、累积振铃计数与应力曲线具有较好的对应关系,振幅总体分布在[42,60]d B之间,随着振幅的增加,声发射事件率呈现出递减的趋势;含瓦斯煤岩失稳破坏时声发射事件率与围压呈线性关系,而声发射累积振铃计数与围压呈指数函数关系;不同围压下含瓦斯煤岩卸围压实验中轴向应力加载阶段和围压卸载阶段能量特征是不同的,随着围压的增大,煤岩加载阶段吸收的能量明显增大,卸载阶段释放的能量也相应的增大,加载阶段和卸载阶段能量变化与初始围压均呈对数关系。

A series of confinement unloading tests have been performed on coal specimens containing gas by using a servo-controlled triaxial stress thermal-device and acoustic emission(AE) monitoring system, test results show that AE rate and accumulative counts have a good corresponding relationship with stress curve under different confining pressures, the amplitude is between [42,60]d B, with amplitude increasing, the rate of AE event decreases; when failure, rate of AE event and confining pressure show linear relationship, and AE cumulative count and confining pressure is an exponential function; during axial stress loading stage and unloading stage of confining pressure, energy feature is different, with the increase of confining pressure, during absorbed energy coal loading stage increases, during released energy the unloading stage increases, the energy change and during the initial loading stage and unloading confining pressure there is a logarithmic relationship.