单轴压缩下花岗岩电荷变化的实验研究

Study on charge change of granite samples under uniaxial compression

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进行了实验研究。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。产生的电荷随着时间衰减。如果应力变化速率大,岩石变形破裂时产生的电荷在短时间内衰减很小,同时又有大量的自由电荷产生,所以在岩石变形破裂时,应力变化速率大时,有较强的电荷感应信号。

With the self-designed charge induction instrument, the charge induction signal of the granite samples in deformation and fracture process is experimently studied under uniaxial compression. The result show： the charge induction signal of the rock in the peak strength is stronger than that before the peak strength. The charge induction signal is influenced by the stress rate of the rock. The charge induction signal is stronger when the stress rate of the rock is bigger. The charge induction signal is stronger during rock cracking. But the charge induction signal is lower in the surface of small deformation and crack of the specimen. Our result suggests that the charge production is in relation to the rock fracture. The charge relaxes over time. The greater the stress change-rate, the stronger the charge induction signal under the rock deformation and fracture.