不同围压下煤岩损伤变形规律及声发射特征分析

Analysis on damage deformation laws and acoustic emission characteristics of coal rock under different confining pressures

为研究不同围压条件下煤岩的损伤变形,利用RTX-1000岩石三轴仪和Micro-Ⅱ声发射成像采集仪对煤样进行不同围压下的三轴压缩声发射定位试验,对加载过程中的应力应变、AE计数等特征参数进行对比分析,构建基于AE计数的损伤模型,研究三轴压缩下煤岩损伤变形的规律。研究结果表明:在保持应变率恒定的条件下,围压越高,煤样的峰值强度越大,分别为18.04,29.92,32.29,45.94MPa;围压越高,弹性阶段的AE计数相对减少;煤样发生剪胀扩容变形;基于AE计数构建损伤模型,分析对比损伤应变理论曲线与试验曲线,得到较高的拟合度,且损伤临界值和损伤量随围压的升高呈现减小的趋势;分析理论模型中的速率增长因子,得到试验与理论损伤规律一致。

In order to study the damage deformation of coal rock under different confining pressure conditions,the triaxial compression acoustic emission location tests under different confining pressures were carried out on the coal samples by using the RX-1 000 rock triaxial apparatus and Micro-Ⅱacoustic emission imaging acquisition instrument.The characteristic parameters such as the stress-strain and AE count in the loading process were compared and analyzed,and a damage model based on AE count was constructed to study the damage deformation laws of coal rock under the triaxial compression.The results showed that under the condition of constant strain rate,the higher the confining pressure,the higher the peak strength of coal sample,which were 18.04,29.92,32.29 and 45.94 MPa respectively.The higher the confining pressure,the relatively less the AE count in the elastic stage.The coal samples occurred the shear dilatation,expansion and deformation.The damage model was constructed based on AE count,then the theoretical curve and experimental curve of damage strain were analyzed and compared,and the relatively high degree of fitness was obtained,furthermore,the critical value of damage and the amount of damage presented the decreasing trend with the increase of confining pressure.The rate-increasing factor in the theoretical model was analyzed,and the experimental and theoretical damage laws were consistent.