不同应力路径下含瓦斯煤的声发射特性与能量演化规律

Acoustic emission characteristics and energy evolution of coal containing gas under different stress paths

为了研究含瓦斯煤在不同扰动作用下的声发射特性和能量演化规律,利用多场煤与瓦斯突出过程宏细观试验系统,开展6种应力路径下的含瓦斯煤轴向加卸载试验,分析应力路径对含瓦斯煤声发射特性和变形特性的影响,并得到含瓦斯煤在循环加卸载过程中的能量演化特征及储能规律。研究结果表明:含瓦斯煤在吸附过程中的振铃计数随吸附时间增长而减少,根据出气口压力变化趋势将吸附过程分为3个阶段,分别为外扩散阶段、内扩散阶段和吸附饱和阶段;含瓦斯煤在加卸载过程中的振铃计数主要分布在应力上升区段,出现了明显的Kaiser效应,累计振铃计数在循环加卸载路径下呈“阶梯”形增长,且随着循环次数增加和应力路径延长而增大;含瓦斯煤在不同循环加卸载路径下的能量演化规律具有一致性,各能量密度均随着轴向应力增加而呈现二次函数型增长,并经历了减速增长、线性增长和加速增长的3个阶段;同时,弹性能密度和总输入能密度之间存在线性关系,储能系数为定值且均在50%以上。

In order to study the AE characteristics and energy evolution law of gas-bearing coal under different disturbances,the axial loading and unloading tests of gas-bearing coal under six stress paths were carried out by using multi-field macro-meso test system of coal and gas outburst process.The effects of stress paths on the AE characteristics and deformation characteristics of gas-bearing coal were analyzed.The energy evolution characteristics and energy storage law of gas-bearing coal during cyclic loading and unloading were obtained.The results show that the ringing count of gas-bearing coal decreases with the increase of adsorption time.According to the change trend of outlet pressure,the adsorption process is divided into three stages,including external diffusion stage,internal diffusion stage and adsorption saturation stage.The ringing count of gas-bearing coal in the process of loading and unloading is mainly distributed in the rising section of stress,and there is an obvious Kaiser effect.The cumulative ringing count increases in a"adder"shape under the cyclic loading and unloading path,and increases with the increase of the number of cycles and the extension of the stress path.The energy evolution law of gas-bearing coal under different cyclic loading and unloading paths is consistent.Each energy density shows a quadratic function growth with the increase of axial stress,and experiences three stages of deceleration growth,linear growth and acceleration growth.At the same time,there is a linear function relationship between the elastic energy density and the total input energy density,and the energy storage coefficient is fixed and above 50%.