Experimental study on EMR during the shearing process of coal

Rockburst of working face in mines, Unstability and destruction of tunnel and ground room and so on are related with the complicated stress. Electromagnetic radiation (EMR) technology can forecast such catastrophes and estimate the stress state of coal or rock body. Therefore, studying on the characteristics of EMR emitted by coal or rock under the complicated stress can settle the before-mentioned estimation and forecast more effectively. This paper showed rules of EMR of coal or rock under shearing destruction by using shearing experimental system in detail. In order to compare, acoustic emission(AE) was recorded synchronously in the shearing process. The results show that in the shearing process EMR has two kinds: one is that EMR increase gradually in the incipience of loading, have a calm zone in the middle of loading, enhance gradually before the main destruction, have higher intensity at the time of destruction, and decrease after the destruction; the other is that EMR increase continually with the increase of stress. till coal is destroyed and decrease gradually after coal is destroyed. And AE is similar to EMR. These results agree with the practical observation of EMR forecasting rockburst and coal or gas outburst. Moreover, we analyzed those phenomena and concluded that AE and EMR derive mainly from friction in the shearing process.