Space-time evolution rules of acoustic emission locations under triaxial compression

Abstract：To study AE space-time evolution rules and energy releasing characteristics during deformation and failure process of coal,a series of triaxial compression tests were carried out by MTS815 rock mechanics test system at different confining pressures,i.e.3.2,9.6,16.0 and 22.4 MPa.The test results find out that,during hydrostatic confining pressure phase,AE signals mainly occurre at the preliminary and medium stage and closely related to the native fissures and pores,and originated mainly from compaction,friction and slip of the fissures;during the stage of axial compression,the space-time evolution corresponds well to the stress-strain curves.The characteristics of acoustic emission are significant when the specimen initially damaged,yield and destroyed.Based on the analysis of AE time series parameters,energy release and the location points,it is found out the ratio of stress at coal failure precursor to peak stress is from 92% to 98%.The experiment also reveales the confining pressure effects of AE during the failure process of coal.Meanwhile,AE space-time evolution corresponds well to evolution process of fracture events which emergs from single to complex and from disorder to order.