白皎煤矿玄武岩岩爆破坏微观裂纹特征分析

为研究煤矿中发生岩爆灾害机理和破坏特征,从岩爆破坏产生的岩石碎屑中微观裂纹结构特征入手,分析在岩爆实验过程中岩石样品的极限应力状态与所产生的裂纹分形维数之间的关系。选取四川白皎煤矿岩爆高发区4个地点的8件玄武岩样品,进行两种加卸载方式的岩爆实验,得到不同加卸载条件下产生的玄武岩岩爆碎屑,利用电子扫描显微镜观察岩爆碎屑表面裂纹微观结构特征,拍摄适当比例的岩爆裂纹电镜扫描(SEM)图片。通过图片处理,提取岩爆碎屑SEM图片微观裂纹信息,计算岩爆微观裂纹分形维数,结果表明两种加卸载方式产生的岩爆碎屑微观裂纹分形维数值明显不同。分析岩爆破坏极限状态下最大主应力和第2主应力比值与岩爆裂纹分形维数之间的关系,得出相应的线性表达式,表明岩爆裂纹的分形维数与岩爆发生过程的应力转化过程关系密切。

Analysis of micro-crack characteristics from rockburst failure of basalt in Baijiao Coal Mine content

This study intends to learn more about the mechanism and feature of rockburst disaster in coal mines from the perspective of micro-cracks observed in the fragments from the laboratory rockburst tests，i.e.，the relationship between the fractal dimensions of the micro-cracks and the corresponding failure stress state from each of the tests.Two types of loading-unloading methods were applied in the laboratory rockburst tests on 8 basalt specimens from 4 locations of Baijiao Coal Mine，where rockburst happened frequently.Scanning Electron Microscope(SEM) technique was used to capture the images of micro-cracks with proper scales，and the fractal dimensions of the micro-cracks were calculated based on the digital information from the images.The results show an obvious difference in the fractal dimensions of the micro-cracks from the tests with two different loading-unloading methods.The relationship between the fractal dimensions of micro-cracks and the ratio of the maximum to the intermediate principal stress(σ1/σ2) at failure was analyzed，and the corresponding quantitative linear formula was obtained，exhibiting a closely correlated relationship between the fractal dimensions of micro-cracks and the process of stress conversion during rockburst.