不同加载速率下小纪汗煤矿煤样强度及声发射特征研究

    Strength and Acoustic Emission Characteristics Under Different Loading Rates for Coal Samples from Xiaojihan Coal Mine

    • 摘要: 利用材料力学试验机及声发射信号检测分析系统,对小纪汗煤矿煤样进行了不同加载速率下单轴压缩过程中的声发射试验,得到了煤样应力应变全过程的声发射特征曲线,分析了不同加载速率下煤样的强度极限、声发射能量及振铃计数等特征参数的变化规律。研究表明:随着加载速率的增加,煤样抗压强度和压缩率呈现先上升后降低的变化趋势, 煤样声发射能量释放形式由孤震型向震群型转变,在低加载速率下岩样能量释放形式主要表现为孤震型,在较高加载速率下则主要表现为震群型;不同加载速率下煤样振铃计数变化趋势大致相同,都经历缓慢增加与快速增加阶段,且随着加载速率的提高,声发射累计振铃计数明显减少;单轴压缩时煤样的破坏表现为单剪及双剪破坏,煤样声发射三维定位图与破裂实物图吻合较好。

       

      Abstract: By material mechanics testing machine and acoustic emission signal detection and analysis system, the uniaxial compression acoustic emission tests under different loading rates of coal samples from Xiaojihan Coal Mine were accomplished and the acoustic emission characteristics curves of coal samples under the complete stress strain process were achieved and the changing laws of characteristic parameters such as ultimate strength, acoustic emission energy, ringing count with the different loading rates have been analyzed. The research shows that: with the increase of loading rate, the compressive strength and compression ratio of the coal samples show the trend of decreasing after the first rise, and the release form of acoustic emission energy for coal samples changes from the lone shock to swarm type, and under the lower loading rate, the energy release form is mainly solitary type and under the higher loading rate, the energy release form is mainly the swarm type; the change tendency of coal samples ringing counts is roughly same under different loading rates, which experienced a slow increase and fast increase stage, and with the increase of loading rate, the cumulative ringing counts of acoustic emission decreased significantly; the damage of coal sample in single axial compression is the single shear and double shear failure, and the three-dimensional positioning map of coal sample acoustic emission is in good agreement with the broken object.

       

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