关键词: 型煤, 静载破坏, 微震, 电磁辐射, 裂纹扩展

Abstract: 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.

Key words: briquette, static loading, micro-seismic, electromagnetic radiation, crack propagation