Acoustic Emission Characteristics And Damage Model Of Limestone With Different Rock Burst Tendencies Under Uniaxial Loading

The research on the mechanism and prevention of deep hard rock rockburst has important engineering significance for reducing the accident rate of mine disasters.In the study of rock failure,acoustic emission technology provides an effective way.At present,many studies have established damage models of various types of rocks based on acoustic emission,but few people have discussed the applicability of different parameters to study rock damage.For the same type of rock,the increase of burial depth will cause changes in its physical properties,and the strength of rockburst tendency depends largely on its physical and mechanical properties.It is obviously inappropriate to use the same model to characterize the damage of rocks with different rockburst tendency.Therefore,the correlation analysis of rockburst tendency with acoustic emission and damage has important theoretical significance for deep mining of deposits.In this paper,the limestone core of-600 m ～-1000 m in the same geological prospecting hole is taken as the research object.The rockburst tendency of limestone with different buried depths is distinguished by laboratory test.The acoustic emission characteristics of the failure process of limestone with different rockburst tendency are analyzed.The damage characteristics of limestone with different AE parameters are discussed.The reasonable parameters characterizing the damage of limestone with different rockburst tendency are obtained.The damage models of limestone with different rockburst tendency are established respectively.It mainly includes the following four aspects of research work:（1）The limestone cores with different buried depths were processed,their physical and mechanical properties were tested,and the indoor experiment of rockburst tendency discrimination was carried out.The elastic energy index W_ET criterion,the deformation brittleness index K_ε criterion and the linear elastic energy index W_e criterion are used to comprehensively discriminate the rockburst tendency of limestone,and the rockburst tendency of limestone with different buried depths is obtained.（2）The uniaxial compression acoustic emission tests of limestone with different rockburst tendencies were carried out.The crack volume strain method was used to divide the stress-strain curves of each rock sample into stages.The acoustic emission characteristics of the failure process of limestone with different rockburst tendency were obtained.The damage and fracture mechanism and energy release characteristics of limestone with different rockburst tendency were analyzed.Based on the characteristics of RA-AF value,the feasibility of r=RA/AF as an evaluation index for the damage degree of limestone with different rockburst tendency was discussed.（3）The AE parameters are used to characterize the damage of limestone with different rockburst tendency.The damage variation characteristics based on different AE parameters are compared and analyzed,and the fractal dimension of each characterization parameter is calculated.The variation coefficient CV of mathematical statistical index is introduced for quantitative analysis of the fractal characteristics,and the reasonable parameters for characterizing the damage of limestone with different rockburst tendency are obtained.（4）Based on the acoustic emission characteristics of limestone with different rockburst tendency,the relationship between rock acoustic emission and strain is deduced.Combined with the basic principle of damage mechanics,the damage models of limestone with different rockburst tendency are established respectively.The physical significance of each damage parameter is analyzed,and the energy release law of limestone with different rockburst tendency is further revealed.