煤岩力学特性降解及声发射信号多参量特征试验研究

    Experimental study on degradation of mechanical properties of coal and rock and multi-parameter characteristics of acoustic emission signals

    • 摘要: 为研究循环荷载作用下煤样断裂演化过程,借助MTS815力学试验机及声发射仪对加卸载过程中煤样力学特性及声发射信号特征展开了深入的研究。结果表明:不同应力水平下,弹性模量表现出3阶段的变化趋势,即急剧增加-缓慢增加-急剧降低;泊松比与不可逆应变呈现出由线性向非线性的演变,即稳定不变-缓慢增加-急剧增加;低、中和高频特征信号占比分别为77.41%、6.18%和16.41%,其中,低频高幅值能量信号是诱导煤样发生宏观断裂的主要特征信号;微观拉伸裂纹和剪切裂纹占比分别为37.9%和62.1%;基于加卸载响应比定义的损伤因子较好地表征了不同加载阶段的损伤演化过程。

       

      Abstract: In order to investigate the fracturing process of coal subjected to cyclic loading, the mechanical properties and the acoustic emission characteristics of coal samples were analyzed using MTS815 mechanical testing machine and acoustic emission instruments. The results show that under different stress levels, the elastic modulus of coal presents a rapid increase, then slow increase and finally sharp decrease trend. Poisson’s ratio and irreversible strain show a three-stage trend, namely, a first slow increase, subsequently gradual increase and finally a significant increase. Low, medium and high frequency characteristic signals accounted for 77.41%, 6.18% and 16.41%, respectively. Among them, low frequency and high amplitude energy signal is the main characteristic signal to induce macroscopic fracture of coal sample. Microtensile crack and shear crack accounted for 37.9% and 62.1%, respectively. Finally, the damage factors defined based on the load-unloading response ratio can better characterize the damage evolution process at different loading stages.

       

    /

    返回文章
    返回