动静荷载作用下灰岩和白云岩破坏机理研究

Research on failure mechanism of limestone and dolomite under dynamic and static loads

为研究岩石在动静荷载作用下的破坏机理,以西南地区常见的灰岩及白云岩为研究对象。通过X射线衍射和电镜扫描讨论岩石固体相及细观结构的差异性,基于岩石三轴试验系统及分离式霍普金森压杆系统开展静力学试验和动态冲击试验,分析岩石在动静荷载作用下的破坏机理。结果表明:灰岩与白云岩固体相物质成分及细观结构存在较大差异性;灰岩在静单轴压缩荷载下以剪切破坏为主,在冲击荷载作用下呈现轴向劈裂破坏;白云岩在静单轴压缩荷载下以劈裂破坏为主,在冲击荷载作用下呈压碎破坏形式;两类岩石的动态抗压强度、单位体积吸收能随应变率的增加显著增大且率相关性明显。岩石固体相及微观结构的差异性是导致其破坏机理不同的重要原因。

Taking common limestone and dolomite in Southwest China as objects, the failure mechanism of rocks under dynamic and static loads is studied.The difference of the solid phase and mesostructure of rocks was discussed by X-ray diffraction and electron microscope scanning.Based on rock triaxial test system and split Hopkinson pressure bar system, static and dynamic impact tests were carried out to analyze the failure mechanism of rock under dynamic and static loads.The results show: There are great differences in solid phase material composition and mesostructure between limestone and dolomite;Limestone under static uniaxial compression load is mainly shear failure and axial splitting failure under impact load;Dolomite is mainly splitting under static uniaxial compression load and crushing under impact load;The absorption energy per unit volume of dynamic compressive strength of the two types of rocks increases significantly with the increase of strain rate, and the rate correlation is obvious.The difference in solid phase and microstructure of rock is the fundamental reason for the different failure mechanisms.