单轴压缩下花岗岩电磁信号的实验研究

利用自主研制的电荷感应仪对花岗岩样品在单轴压缩变形破裂过程中产生的电荷感应信号和磁信号进行了实验研究。实验结果表明,在岩石变形破裂达到峰值强度时比在峰值强度前有更强的电荷感应信号产生,电荷感应信号也受岩石应力的变化速率影响,在应力变化速率大时,有较强的电荷感应信号。在有变形破裂时,电荷感应信号就较强,变形破裂较小的面所对应的测点的电荷感应信号就较小,这表明电荷的产生和岩石的破裂有很大的关系。电信号比磁信号多,在岩石变形破裂时不断有电信号产生,且有明显的变化,而磁信号的变化不明显。电信号相比磁信号受外界的干扰小,幅值大,说明用电荷感应的方法监测岩石的变形破裂前兆更有优势。

Study on the charge and magnetic signals of granite samples under uniaxial compression

With the designed charge induction instrument, the charge induction signal and magnetic signal of the granite samples in deformation and fracture process were experimently studied under uniaxial compression. The results showed, the charge induction signal of the rock in the peak strength is stronger than that before the peak. The charge induction signal is influenced by the rate of stress in the rock. The charge induction signal is stronger when the stress rate is bigger. The charge induction signal is stronger during rock cracking. But the charge induction signal is lower in the part with small deformation and crack in the specimen. Our results suggested that the charge production is related to the rock fracture. The charge induction signal of the granite samples in deformation and fracture process is more than the magnetic signal. Changes are obvious in the charge induction signal but not in the magnetic signal. There is less interference in the charge induction signal than in magnetic signal. The results suggested that using charge induction to monitor the precursor of rock deformation and fracture is advantageous.