3D Crack Distribution Model of Rock Mass using AE induced by Coal Mining

在这项研究中，岩石和煤样产生的Dartbrook煤矿，澳大利亚，实验室实验和AE在开采过程中观察到的线进行分析，以构建三维分形模型的裂纹分布在煤矿盘区周围的岩石。通过对煤、砂岩、粉砂岩等17块岩样进行单轴和三轴压缩试验，验证了模型的可靠性。实验结果如下：结果表明：随着围压的增加，煤岩中的声发射事件数逐渐减少;加载过程中的声发射活动与岩石的种类有关;声发射波形可以通过加速度波形的微分来估计;利用矩张量分析法建立了煤岩中裂纹分布的三维分形模型;利用VRML实现了模型的可视化;煤岩和砂岩中的裂纹分布模型均以剪切型裂纹为主。分析了声发射源的位置和矩张量。1）发现由20个三轴速度计组成的三轴声发射传感器的各轴不能由爆破试验波形确定。2）因此，通过常规声发射源定位分析，确定了大部分声发射源，通过矩张量分析建立了岩体三维裂隙分布模型声发射活动度和三维裂隙分布模型反映了采场开采活动和工作面发生的小规模冒顶等事件，验证了模型的有效性。

In this study, laboratory experiments for rock and coal samples produced at Dartbrook Coal Mine, Australia, and analysis of AE observed during mining at the line were conducted in order to construct the 3D fractal model of crack distribution in the rocks around coal mine panel. The reliability of the model was also confirmed comparing with the events occurred during mining.For 17 pieces of rock samples of coal, sandstone, silt stone, uni-and tri-axial compression tests were carried out. The experimental results are :1)It was found that the number of AE event was decrease with increase of the confining pressure.2)AE activity during loading was dependent on the kind of rock.3)It was found that the AE wave forms detected during tests were estimated the differential of acceleration waveform.4)3D fractal models of crack distribution in the specimens were constructed by the moment tensor analysis.5)Visualization for the model was realized by VRML.6)The crack distribution models showed that shear type cracks were dominant for coal and sandstone specimens.For two hundred thousand AE waveforms recorded in the mine from August to October in 1999, AE source location and moment tensor were analyzed The analytical results are :1)It was found that the each axis of tri-axial AE sensor composed 20 tri-axial velocity meters was not determined from blasting test wave forms.2)Therefore, by the conventional AE source location analysis most of AE sources were determined, and the 3D crack distribution model of rock mass was constructed by the moment tensor analysis.3)The AE activity and 3D crack distribution model reflected the mining activity and some events such as small scale rock fall occurred at the working face, and the effectiveness of the model was found.