In order to study the correlation between micro-seismic

electromagnetic radiation signals and crack evolution characteristics of briquette under uniaxial compression loading

the failure experiments were carried out at four different range of particle sizes including 0–0.25 mm

0.25–0.5 mm

0.5–1.0 mm and 1–2 mm by means of self-designed and low-noise static loading experimental system. In addition

the micro-seismic

electromagnetic radiation signals and damage videos recorded during the failure of the briquette were collected synchronously. Based on the image semantic segmentation software

a fast crack extraction method on coal mass surfaces was proposed

and the variation law of crack area of briquette was calculated. The results show that the micro-seismic

electromagnetic radiation signals and crack area generated by briquette under the uniaxial compression process have a good correlation in the time domain. The curve of crack area with time in the process of briquette failure can be divided into four stages. In the first stage

the briquette is under compaction

the stress value is small

and the crack area on the surface increases at a very slow rate. In the second stage

with the increase of stress and the accumulation of internal elastic potential energy

the rate of increase of the surface area of the briquette is significantly higher than that of the first stage

accompanied by many fine cracks. In the third stage

as the stress continues to increase and the elastic energy is accumulated inside the material

the deformation process of the sample is accelerated

resulting in a further increase in the crack area. In the last stage

the crack area of the sample reaches its peak

the bearing capacity decreases sharply

the instability occurs

and the loading process ends.