Experimental Study on Mechanical Effects of Pore-Permeability Fractal Characteristics of Coal Rock Based on Variable-Mass System of Coal Mine Geological Water

Particle loss is the root cause of sudden water inrush events in Karst Collapse Pillar coal mines, and pore damage in Karst Collapse Pillar fills can further induce seepage destabilization, which is a process that geological sudden water inrush events must undergo. To investigate the direct relationships among stress conditions, water pressure conditions, and gradation structure on the pore structure of rock samples, an innovative seepage system for variable-mass fractured rock masses was developed using the steady-state seepage method. The results show that the fractal-structure characteristics of particles are closely related to the crushing process and softening effect of water under the same stress state. Rubbing, rotating, fracturing, grinding, and plugging are the main forms of the intergranular action therein. The filling particles before and after the loss of flow meet the fractal conditions and have fractal characteristics. The percentage of fine particles in the whole process of infiltration loss is as high as 34.4%, and the reciprocal action of water flow forms a stable water-conducting channel. The above research methods and conclusions provide new experimental research methods and ideas for the theoretical study of mine water-surge disaster systems.