EXPERIMENTAL STUDY ON ULTRA-LOW FRICTION EFFECT AND ACOUSTIC EMISSION CHARACTERISTICS OF COAL-ROCK INTERFACE WITH DIFFERENT ROUGHNESS

To reveal the influence mechanism of coal-rock interface roughness on ultra-low friction rock burst under dynamic load disturbance, a self-developed ultra-low friction test device for coal-rock interface is used. The coal rock block of 1082 m mining depth in Shenyang Hongyang Three Mine is used as the research object. Different roughness characteristics of coal-rock interface is simulated by changing the surface roughness of coal block and sandstone block. The roughness coefficient is used to characterize the surface roughness of coal rock, the horizontal displacement of working block is used to characterize the strength of ultra-low friction effect in the impact process, and the AE energy is used as the signal parameter in the friction and sliding process of working block. The ultra-low friction test of coal-rock interface with different roughness under stress wave disturbance is carried out. The results show that: (1) In the process of ultra-low friction sliding, the horizontal displacement, AE energy count and cumulative energy curve of the working block show the characteristics of incubation stage, excitation stage and stable stage. (2) The smaller the roughness of the coal-rock interface is, the larger the horizontal displacement and the peak value of AE energy of the working block are, and the ultra-low friction effect is more likely to occur at the coal-rock interface. (3) Under different coal-rock interface roughness, compared with other disturbance frequencies, ultra-low friction effect is more likely to occur at 2 Hz. (4) The relationship between the peak value of acoustic emission energy and the roughness coefficient of coal-rock interface is given. The strength of ultra-low friction effect can be effectively characterized by the peak of acoustic emission energy, and the peak of AE energy can be used to predict the strength of ultra-low friction effect.