单向扰动加载触发煤体冲击破坏特性试验研究

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)。

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

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 slowly increase rapidly increase suddenly”.Failure form of coal mass experienced a “shear failure vertical splitting failure burst 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.