Pressure stimulated current in progressive failure process of combined coal-rock under uniaxial compression: Response and mechanism

Effective monitoring of the structural health of combined coal-rock under complex geological conditions by pressure stimulated currents (PSCs) has great potential for the understanding of dynamic disasters in underground engineering. To reveal the effect of this way, the uniaxial compression experiments with PSC monitoring were conducted on three types of coal-rock combination samples with different strength combinations. The mechanism explanation of PSCs are investigated by resistivity test, atomic force microscopy (AFM) and computed tomography (CT) methods, and a PSC flow model based on progressive failure process is proposed. The influence of strength combinations on PSCs in the progressive failure process are emphasized. The results show the PSC responses between rock part, coal part and the two components are different, which are affected by multi-scale fracture characteristics and electrical properties. As the rock strength decreases, the progressive failure process changes obviously with the influence range of interface constraint effect decreasing, resulting in the different responses of PSC strength and direction in different parts to fracture behaviors. The PSC flow model is initially validated by the relationship between the accumulated charges of different parts. The results are expected to provide a new reference and method for mining design and roadway quality assessment.