scholarly journals Size Effect on Acoustic Emission Characteristics of Coal-Rock Damage Evolution

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Zhijie Wen ◽  
Xiao Wang ◽  
Lianjun Chen ◽  
Guan Lin ◽  
Hualei Zhang
Keyword(s):  
Acoustic Emission ◽  
Size Effect ◽  
Damage Evolution ◽  
Effective Means ◽  
Strain Range ◽  
Emission Characteristics ◽  
Peak Strain ◽  
Rock Damage ◽  
Rock Body ◽  
Coal Rock

Coal-gas outburst, rock burst, and other mine dynamic disasters are closely related to the instability and failure of coal-rock. Coal-rock is the assemblies of mineral particles of varying sizes and shapes bonded together by cementing materials. The damage and rupture process of coal-rock is accompanied by acoustic emission (AE), which can be used as an effective means to monitor and predict the instability of coal-rock body. In this manuscript, considering the size effect of coal-rock, the influence of different height to diameter ratio on the acoustic emission characteristics of coal-rock damage evolution was discussed by microparticle flow PFC2D software platform. The results show that coal-rock size influences the uniaxial compressive strength, peak strain, and elastic modulus of itself; the size effect has little effect on the acoustic emission law of coal-rock damage and the effects of the size of coal-rock samples on acoustic emission characteristics are mainly reflected in three aspects: the triggering time of acoustic emission, the strain range of strong acoustic emission, and the intensity of acoustic emission; the damage evolution of coal-rock specimen can be divided into 4 stages: initial damage, stable development, accelerated development, and damage.

scholarly journals Research on Acoustic Emission Characteristics and Constitutive Model of Rock Damage Evolution with Different Sizes

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Haijiang Zhang ◽  
Xiaohu Zhang ◽  
Hongbo Zhou
Keyword(s):  
Acoustic Emission ◽  
Constitutive Model ◽  
Scale Effect ◽  
Damage Evolution ◽  
Failure Modes ◽  
Development Stage ◽  
Diameter Ratio ◽  
Emission Characteristics ◽  
Peak Strain ◽  
Evolution Law

In this study, considering the scale effect of rock mass, the influence of different height-to-diameter ratios on rock mechanics and acoustic emission characteristics was studied by using PFC2D software. The damage constitutive model of rock was established, and the damage evolution characteristics of rock with different height-to-diameter ratios were further analyzed. The results showed that, with the increase of height-to-diameter ratio K, the uniaxial compressive strength and peak strain of rock exhibited a gradual decrease; however, the elastic modulus gradually increased. Moreover, rock failure modes exhibited different characteristics under different K values. The scale effect showed little influence on the acoustic emission characteristics in the elastic stage; nonetheless, in the plastic deformation stage and the residual damage stage, with the increase of the rock’s height-to-diameter ratio, the maximum number of impacts of acoustic emission increased, the range of strong strain of acoustic emission decreased, and the maximum time of acoustic emission impacts increased gradually. The height-to-diameter ratio of the rock slightly influenced the zero-damage stage of the rock, but the damage affecting the rock increased slowly and accelerated the development stage. The damage evolution law was found to be similar when the K values varied from 1.0 to 2.0; however, when the K was greater than 2.0, the damage evolution law exhibited the characteristics of slowing down in the acceleration phase.

scholarly journals Analysis of Mechanical and Acoustic Emission Characteristics of Rock Materials with Double-Hole Defects Based on Particle Flow Code

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Qi Zhang ◽  
Xiao Wang ◽  
Long-gang Tian ◽  
Dong-mei Huang
Keyword(s):  
Acoustic Emission ◽  
Damage Evolution ◽  
Failure Modes ◽  
Numerical Models ◽  
Strain Range ◽  
Peak Strength ◽  
Particle Flow Code ◽  
Stress Strain ◽  
Rock Materials ◽  
Connection Line

There are a lot of fissures, holes, and other defects in the formation of natural rocks. Under the influence of the external loads, these defects may cause engineering problems. Therefore, it is of great significance to analyze the characteristics of damage evolution of the defective rocks. In the study, the double-hole defective rocks with different angles of the center connection line are considered and the numerical models are established firstly. Then the mechanical behavior and acoustic emission (AE) characteristics are analyzed systematically. Finally the laws of damage evolution of the defective rock materials are investigated based on the AE characteristics. The research results show that the stress-strain behavior of the defective rocks can be divided into elastic stage, plastic stage and failure stages. The characteristics of acoustic emission evolution and laws of damage evolution are closely related to the stress-strain relationship. The elastic modulus of the double-hole defective rocks is similar with different angles of the center connection line, but the peak strength is different. The shape of the peak strength of these defective rocks is a W type owing to the different failure modes. The influences of different angles of the center connection line on the characteristics of AE evolution include the maximum events number, the strain value of the initial AE events and the maximum AE events, and the strain range of the serious AE events. Different angles of the center connection line have different influences on the laws of damage evolution of the double-hole defective rocks.

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