Experiment and analysis of coal sample destruction precursor based on load-unload response ratio

The paper researched and analyzed response ratio characteristics of acoustic emission and electromagnetic radiation of coal sample in load-unload by experiment based on load-unload response ratio theory , and got conclusions: ① Load-unload response ratio of acoustic emission and electromagnetic radiation can well reflect stable state of coal samples in process of homotaxial load-unload, and load-unload response ratio is lower when coal sample status is stable , otherwise is higher. ② The coal samples will begin to follow itself evolution rule after the load-unload response ratio increased to peak, and the load-unload response ratio has process 'sharp growth-quickly dow' before the coal samples break, which can be used to predict macroscopic damage of the coal sample. ③ Peak time and macroscopic damage time of the load-unload response ratio is inconsistent because of inhomogeneity of the coal sample, so when method of load-unload response ratio is used to predict disaster, uneven degree of coal and rock should be considered to determine characteristic time. The experiment results show that predicting coal or rock dynamic disasters has certain feasibility by load-unload response ratio of acoustic emission and electromagnetic radiation.