RESEARCH ON ELECTROMAGNETIC RADIATION RULES OF COMPOSED COAL-ROCK BURST FAILURE

It is known that wide frequent electromagnetic radiation(EMR) signals can be produced in the processes of deformation and failure of coal and rock by many theoretical researches and physical experiments.So,the EMR rules of deformation and failure of coal and rock body composed of hard roof,coal body and floor are important to predict and forecast the coal and rock dynamic calamity.The EMR and acoustic emissions(AE) phenomenon in the rock burst process are investigated by using the Disp-24 acoustic-electromagnetic system and MTS loading system in the laboratory.The results show that the intensity of EMR signals rises slowly before burst failure but increases suddenly when burst failure occurs.The counts of AE signals increase suddenly to maximum value before failure,and suddenly decline.During the period of impact rupture of combined samples,the time when signal peaks of EMR and AE appear are not synchronous,and the maximum EMR signals appear at stage after peak stress.However,the maximum AE signals appear at the peak stress.The AE signals are comparatively weak when EMR signals reach to peak values;and EMR signals are comparatively weak when the AE signals reach to maximum values.With the achieved rules,the danger of rock burst can be evaluated and forecasted.