单向扰动加载触发煤体冲击破坏特性试验研究

Experimental study on the shock failure feature of coal triggered by uniaxial dynamic loading

运用MTS-C64. 106型压力机开展纯煤试件的单轴动静组合加载试验。结合PIC-2声发射卡和高速摄像机的监测结果,分析了单向扰动加载下煤体的力学、冲击性能、声发射特征、动态破坏特征、碎片分形特征。结果表明,扰动加载应变率增大,煤体强度呈对数增加;冲击性能增强;扰动能量输入速率、声发射振铃计数、撞击数呈现"缓增—急增—突增"的转变,试件破裂形式经历"剪切破裂—竖向劈裂—爆裂"的转变;碎片质量分维与动载应变率呈二次方关系,存在动载应变率极值使试件破坏程度达到最大,试验显示的应变率极值为2. 8×10^(-3)s^(-1)。

The uniaxial static and dynamic loading experiments wereexecuted by using MTS-C64.106 press.Mechanical properties,rock burst performance,AE feature,dynamic failure feature and fractal dimension feature of coal mass were investigated by combining the monitoring results of PIC-2 and high-speed camera.Along with the increase of dynamic loading strain rate,the coal mass strength increased by following a logarithmic function,and the rock burst danger also increased.The disturbed energy input rate,the amount of AE and strike inccidents varied as“increase slowlyincrease rapidly-increase suddenly”.Failure form of coal mass experienced a“shear failure-vertical splitting failureburst failure”.It showed a quadratic relationship between the fractal dimension of fragments and dynamic loading strain rate.There must be a dynamic loading strain rate,which achieves the strongest rock burst,and it is 2.8×10^-3 s^-1 according to the experiment results.