煤矿泥岩冲击动态力学特性与破裂破碎特征分析

Analysis dynamic mechanical characteristics and fracture breaking characteristics of coal mine mudstone

煤矿巷道围岩在采掘过程中受多种动载作用,为了研究动载对围岩破坏变形的影响,通过直径50 mm分离式Hopkinson试验装置开展不同冲击气压下煤矿常见泥岩在冲击荷载作用下的动态力学特性和破裂破碎特征试验,研究了不同冲击气压状态下试件应力应变特征、破坏形态和试件动态强度随应变率增长规律,分析了试验过程中应力波传播与试件裂纹扩展的关系。结果表明:在设定的试验条件下,泥岩试件的加载率、应变率和峰值应变均表现出随冲击气压的增大而增大;试件的动态单轴抗压强度随着应变率的增加呈现指数型增长,表现出强应变率效应;试件在反射应力波与透射应力波共同作用下,产生环向拉裂破坏和轴向劈裂破坏。

In order to study the influence of dynamic load on surrounding rock of soft rock roadway in coal mines,a diameter 50 mm separated Hopkinson test device was used to test the dynamic mechanical characteristics and fracture characteristics of common mudstone under impact loading in a coal mine under different impact pressures.Combined with the failure modes of specimens,the dynamic mechanical parameters of specimens under different impact pressures were analyzed.The results of the study show that:the growth rate of stress,strain and the maximum strain of the mudstone increase with the impact pressure;the dynamic uniaxial compressive strength of mudstone show exponential growth with the strain rate,which shows strong strain rate effect;the shale test specimen is in the reflection stress wave and transmission stress;under the combined action of the reflected stress wave and the transmission stress wave,the mudstone specimen produces circumferential failure and axial splitting failure.