An Experimental Study of the Electromagnetic Emission Memory Effect During Deformation and Fracture of Coal or Rock

Abstract

We study characters, contents and their change regularities of electromagnetic emission (EME) memory effect during deformation and fracture of raw coal and molding coal by experimental methods under uniaxial compression. Its mechanism is discussed and analyzed. The results show that EME of coal or rock has an ability of memorizing the previous received maximal stress, longitudinal strain, lateral strain and cubical strain. The direct memory contents of coal or rock EME are previous maximal stress, longitudinal and lateral strain. Its memory ability rapidly weakens or entirely loses when the previous exerting stress level exceeds 70%~80% of the strength. The irreversibility of EME process is decided by the irreversibility of coal or rock damage fracture process. The irreversibility of coal or rock EME process is the direct reason why EME during has memory effect deformation and fracture of coal or rock. The theory of coal or rock EME memory effect has broad application prospects in measurements of crustal stress, determination of different stress areas in surrounding rock of tunnel and the prediction of coal or rock dynamic disasters.