峰值前后多次加载下煤样声发射特征

掌握峰值前后多次加载下煤样声发射变化规律，对研究煤矿开采中不同变形部位煤岩裂缝演化至关重要。利用RMT-150B型岩石力学实验系统以及CDAE-1全数字化声发射检测及分析系统，采取焦作矿区煤样进行了峰值前后多次加载下的应力-应变-声发射测试实验。测试结果显示:首次加载时声发射参数呈现“渐变性”的变化特征，随后加载时声发射变化呈现“分段性”特征。并且随着加载次数的增加煤岩的Felicity效应逐渐增强，体现了煤岩记忆的超前性。同时，随着加载次数的增加，煤样时间-声发射曲线较时间-应力曲线的滞后性逐渐增强。这些特征的研究可以为煤矿井下地质灾害的监测、预测提供指导。

Acoustic emission characteristics of coal samples under multiple loading processes before and after the peak value

For studying the evolution of coal and rock fractures at different deformation sites in mining of coal mine, it is vitally important to grasp the variation laws of acoustic emission for coal samples under multiple loading processes before and after the peak value. By using the RMT-150B rock mechanics test system and CDAE-1 all-digital acoustic emission detection and analysis system, the test experiments on stress, strain and acoustic emission were conducted on coal samples of Jiaozuo mine area under multiple loading processes before and after the peak value. The results showed that in the first loading process, the acoustic emission parameters presented the change characteristic of graduality, while in the subsequent loading process, the change of acoustic emission presented the characteristic of segmentation. With the increase of loading times, the effect of Felicity increased gradually, which reflects the advance of coal memory. At the same time, with the increase of loading times, the hysteresis for curves of time-acoustic emission increased gradually compared with the curves of time-stress. It can provide guidance for the monitoring and prediction of geological disaster in underground coal mine.