岩石动力破裂及其电磁辐射信号特征分析

Dynamic Rupture of Rocks and Analysis of Their Electromagnetic Radiation Signal Characteristics

为提高电磁辐射预测煤岩体动力灾害的准确性,设计霍普金森杆冲击试验,监测收集岩石破裂时产生的电磁辐射信号,并对信号使用小波变换的迭代阈值方法进行去噪,将处理后的电磁辐射信号结合砂岩承受冲击荷载后的应力特征,总结出砂岩冲击破坏时电磁辐射的产生规律.结果表明:根据砂岩遭受冲击后的破坏形态,可将其分为冲击压缩破坏与冲击拉伸破坏;产生破裂时电磁辐射有较大增强,随后随着应力波波谷传递至试件开始降低,而拉伸破坏的试件在此时发生拉伸破坏也会导致较大的电磁辐射波动,在应力波震荡过程中裂隙逐渐扩展,电磁辐射会逐渐增大直至试件完全破坏不再产生电磁辐射;裂隙扩展阶段电磁辐射强度增大,岩石破裂后电磁辐射的强度降低,且具有幅值小、频域窄、主频低等特征.

In order to improve the accuracy of electromagnetic radiation prediction of dynamic disasters in coal rock mass,the Hopkinson rod impact experiment is designed,the electromagnetic radiation signal generated when the rock is broken is monitored and collected,and the signal is denoised by using the iterative threshold method of wavelet transform,and then the treated electromagnetic radiation signal is combined with the stress characteristics of the sandstone after the impact load,and the electromagnetic radiation generation law is summarized when the sandstone is destroyed by impact.Results show that according to the failure form of sandstone after impact,it can be divided into impact compression failure and impact tensile failure.When the rupture is generated,the electromagnetic radiation will be greatly enhanced,while the stress wave trough is transmitted to the specimen begins to decrease,and the tensile failure of the specimen at this time will also lead to a large fluctuation of electromagnetic radiation.The electromagnetic radiation during the subsequent stress wave oscillation process of the fracture expansion process will gradually increase until the test piece is completely destroyed and cannot produce electromagnetic radiation.The intensity of electromagnetic radiation increases during the fracture expansion stage,and the intensity of electromagnetic radiation decreases after rock rupture,and it has the characteristics of small amplitude,narrow frequency domain and low main frequency.