煤岩组合体变形破裂声发射特征及损伤演化规律研究

Acoustic emission characteristics and damage evolution of coal and rock combination bodies during deformation and fracture

为研究煤岩组合体变形破裂过程中煤厚对其声发射特征和峰前损伤特性的影响,对煤厚分别为20mm、33.33mm和60mm的三种煤岩组合体进行室内单轴压缩声发射试验。研究表明:随着煤厚的增加,煤岩组合体的单轴抗压强度和声发射峰值计数均下降,且煤厚与声发射峰值计数满足指数函数关系;组合体的破坏持续时间随煤厚的增加而变长;声发射累计数的变化情况可分为缓慢增长阶段、快速增长阶段和声发射峰值及破坏后阶段,前两个阶段,累计数增长的速度与煤厚呈正相关,最后一个阶段,呈负相关。组合体峰前损伤演化可分为初始损伤、损伤稳定发展和损伤突增不稳定发展三个阶段;损伤变量与应变满足幂指数函数关系,且随着煤厚的增加,组合体D=1时对应的峰值应变也增加。

In order to study the influence of coal thickness on acoustic emission characteristics and pre-peak damage characteristics of coal-rock combination bodies during deformation and fracture, uniaxial compression acoustic emission tests were carried out for three coal-rock combination bodies with coal thickness of 20mm, 33.33mm and 60mm, respectively. The results show that with the increase of coal thickness, the uniaxial compressive strength and acoustic emission peak count of coal and rock composite decrease, and the relation between coal thickness and acoustic emission peak count satisfies exponential function. The failure duration of composite increases with the increase of coal thickness. The variation of ae cumulative count can be divided into slow growth stage, rapid growth stage and peak acoustic emission stage. In the first two stages, the growth rate of ae cumulative count is positively correlated with coal thickness, and in the last stage, it is negatively correlated. The pre-peak damage evolution of the composite body can be divided into three stages: initial damage, stable damage development and sudden and unstable damage development. The relationship between damage variable and strain satisfies power exponential function, and with the increase of coal thickness, the corresponding peak strain increases when D=1.