单轴压缩条件下煤样电荷感应试验研究

EXPERIMENTAL STUDY OF CHARGE INDUCTION OF COAL SAMPLES UNDER UNIAXIAL COMPRESSION

利用自主研制的电荷感应仪,建立单轴压缩条件下煤岩变形破裂过程电荷感应信号测试系统。通过室内试验,研究同一矿区煤在不同加载速率下的变形破裂过程的电荷感应规律。试验结果表明,煤在变形破裂过程中有电荷感应信号产生,电荷感应信号是瞬时脉冲信号;煤样在临近峰值应力时电荷感应信号最强,在煤样破坏时电荷感应信号也较强;煤样变形破裂过程中不同表面的电荷感应信号强度不同,且不完全同步,较大破裂面的电荷感应信号更强;加载速度越大,所产生的电荷感应信号越强、越丰富;煤样在突然加卸载时,有电荷感应信号产生。煤变形破裂过程产生电荷的主要原因是微破裂导致裂隙尖端电荷分离和摩擦作用。电荷感应信号与煤的破裂有一定关系,可以用电荷感应信号反映煤的变形破裂状态。因此,电荷感应方法可作为检测煤变形破坏过程的新手段,也为评定冲击地压等煤岩动力灾害提供一种新的方法和手段,值得深入研究。

Using the self-developed charge-induced instrument,the experimental system for collecting the charge-induced signal in the process of coal deformation and fracture is set up. The law of charge induction of coal in the same mine during the coal deformation and fracture process is studied under different loading rates in laboratory. The experimental results show that the charge-induced signal is generated during the deformation and fracture process of coal;and the charge-induced signal is the instantaneous pulse. The charge-induced signal strength is the most powerful before the peak stress of coal;and the signal strength is more powerful when coal damages. The charge-induced signals on all surfaces are asynchronous,and their magnitudes are varied. The charge-induced signal strength is more powerful at the larger fracture surface. The greater the loading rate is,the stronger the charge-induced signal strength is. Under sudden loading and unloading,there would generate charge-induced signal with low strength. The main reasons for charge generation in the process of coal deformation and fracture are friction and crack tip charge separation because of micro-rupture. The results suggest that the charge-induced signal is closely related to the deformation and fracture of coal;the status of coal deformation and fracture may be determined by the charge-induced signal. The charge induction method is applicable to studying the exploration of the rock deformation and failure process and predicting catastrophic dynamic phenomena.