Study on characteristics and rules of surface potential during coal fracture

The surface potential of coal was studied during different fracture modes, including uniaxial compression, tensile fracture and three-point bending. The results show that a surface potential is produced during the fracture of coal and that the surface potential has a good correspondence to the load: the correlation coefficient between them can be as great as 0.6 to 0.9. The change in load induces the change in the surface potential. The larger the load the higher the surface potential becomes, and vice versa. The magnitude of the surface potential is not the same at electrodes located in different positions on the coal sample. The differences also change along with the change in load and the fracture state of the coal sample. Based on the correlation between surface potential and load, the status of a coal fracturing under load may be determined from the surface potential.