小纪汗煤样在塑性流动下力学性质试验研究

    Experimental study on mechanical properties of Xiaojihan coal samples under plastic flow

    • 摘要: 为了研究小纪汗主含水煤层在采动影响下塑性流动性质和滞回特性,进行了不同围压下的轴向循环加卸载试验;当峰后轴向应力降到峰值应力的70%时开始循环加卸载轴向压缩试压,分析滞环的割线模量、宽长比及相邻滞环的轴向峰值应力比的变化规律。结果表明:随着围压的增大,轴向应变-轴向应力滞回曲线、径向应变-轴向应力滞回曲线的割线模量和宽长比增大,相邻滞环的轴向峰值应力比减小;随着循环次数的增大,轴向应变-轴向应力滞回曲线、径向应变-轴向应力滞回曲线的割线模量和宽长比减小;对于近似相同初始应力状态,围压对滞回曲线的几何特征量和塑性流动具有显著影响。

       

      Abstract: In order to study the plastic flow properties and hysteresis characteristics of Xiaojihan main water-bearing coal seam under the influence of mining, the axial cyclic loading and unloading tests under different confining pressures were carried out. When the axial stress after the peak drops to 70% of the peak stress, the cyclic loading and unloading axial compression test is started, and the secant modulus, width-length ratio of the hysteresis ring and the change law of the axial peak stress ratio of the adjacent hysteresis ring are analyzed. The results show that: with the increase of confining pressure, the secant modulus and width-length ratio of the axial strain-axial stress hysteresis curves and the hoop strain-axial stress hysteresis curve increase, while the axial peak stress ratio of the adjacent hysteretic loops decreases; with the increase of the number of cycles, the secant modulus and the width-length ratio of the axial strain-axial stress hysteresis curves and the hoop strain-axial stress hysteresis curves decrease. For approximately the same initial stress state, the confining pressure has a significant effect on the geometric characteristics of the hysteresis curve and the plastic flow.

       

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