Experimental Investigation on Damage Characteristics and Early Warning of Frozen Coal under Uniaxial Compression

Abstract

This article conducted acoustic emission tests of natural coal, natural frozen coal, and saturated frozen coal to explore the damage characteristics of frozen coal and in view of the frozen coal damage early warning problems and explored the strength deformation and acoustic emission characteristics of coal samples. The test results showed that the compressive strength of the frozen coal samples decreased significantly, and the strength of the saturated frozen coal samples was the lowest; more acoustic emissions were generated at the initial loading stage. The damage parameters were defined using the acoustic emission parameters. The damage characteristics of the coal samples were analyzed. The damage model of the coal samples was established based on the power function. The early warning parameter VAEi to analyze the evolution characteristics of the variance curve was proposed; the sudden jump point b of VAEi from the stable development stage to the rapid growth stage was defined as a general early warning point; the endpoint point c of the parameter rapid growth stage was defined as a key early warning point; a zonal and hierarchical early warning was finally proposed.