循环载荷下软硬煤样的疲劳损伤差异性研究

为研究软、硬两种煤样的疲劳损伤差异性,采用等幅三角波循环加卸载方式进行循环载荷试验,通过对比分析两种煤样的力学特性和声发射参量的差异,揭示软、硬煤样的疲劳损伤机制。试验结果表明：循环载荷下,软煤煤样出现连续的滞回环,硬煤煤样的滞回环基本重合。声发射参量均表现出明显的循环特性,整个试验过程中,硬煤煤样的峰值振铃数相当,软煤煤样呈现“先稳定后依次降低”的规律;硬煤煤样的声发射累计能量和撞击数呈“阶梯状直线上升”趋势,而软煤煤样出现明显的“转折点”。声发射参量的动态变化表明循环载荷下软、硬煤样的损伤演化过程存在明显差异,进而为不同煤体破裂机理研究及煤岩动力灾害的预测和防治提供指导依据。

Research on Fatigue Damage Difference of Soft and Hard Coal Samples under Cyclic Loading

In order to study the difference of fatigue damage between soft and hard coal samples, the cyclic loading and unloading method of constant amplitude triangular wave was adopted. the cyclic load test was carried out by equal amplitude triangular wave cyclic loading and unloading. By comparing and analyzing the differences of mechanical properties and acoustic emission parameters between the two coal samples, the fatigue damage mechanism of soft and hard coal samples is revealed. The results showed that under cyclic load, continuous hysteresis loops appear in soft coal samples, and the hysteresis loops of hard coal samples basically coincide. The acoustic emission parameters show obvious cyclic characteristics. During the whole test process, the peak ringing number of hard coal samples is equivalent, and the soft coal samples show the law of "stabilizing first and then decreasing in turn"; The cumulative acoustic emission energy and impact number of hard coal samples show a "ladder like straight-line upward" trend, while soft coal samples show an obvious "turning point". The dynamic changes of acoustic emission parameters show that there are obvious differences in the damage evolution process of soft and hard coal samples under cyclic load, which provides a guiding basis for the study of fracture mechanism of different coal bodies and the prediction and prevention of coal and rock dynamic disasters.