Experimental study on pressure stimulated current response characteristics during damage evolution of water-bearing coal samples

The damage and rupture behavior of water-bearing coal induced by coal mining disturbance can lead to large-scale rock engineering instability and engineering geological disasters. In order to study the influence of water on the pressure stimulated current (PSC) characteristics, four groups of coal samples with different water contents were set for uniaxial compression test. The response characteristics of PSC signals for water-bearing coal are analyzed, and the evolution characteristics of PSC energy are discussed. The results show that water can significantly reduce the mechanical strength of coal samples. The variation of PSC signals is complex and weak in the early loading stage, and the change in the late stage is severe. With the water contents enhanced, the PSC peak value of coal samples increases. Meanwhile, the increase amplitude of PSC and the percentage between the increase in PSC and the change in stress from elastic stage to plastic stage show linear and exponential increasing relationships respectively. The accumulated charge released gradually increases with the water contents and is affected by the increase of stress. The peak value of time function F based on acoustic emission (AE) hits gradually increases with the water contents. The PSC energy can well reflect the coal damage as well as damage variable. The PSC signals can provide forecast information for upcoming fracture as well as AE activity. The electrokinetic effect generated by water–rock interaction can significantly promote the strength of PSC signals.