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

Abstract

ere 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. erefore, 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. en 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. e research results show that the stress-strain behavior of the defective rocks can be divided into elastic stage, plastic stage and failure stages. e characteristics of acoustic emission evolution and laws of damage evolution are closely related to the stress-strain relationship. e elastic modulus of the double-hole defective rocks is similar with different angles of the center connection line, but the peak strength is different. e shape of the peak strength of these defective rocks is a W type owing to the different failure modes. e 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.

Failure Behavior of F Shape Non-Persistent Joint under Experimental and Numerical Uniaxial Compression Test

“…The reason why we analyze the acoustic emission properties (AE hits) of jointed rock mass in the process of compression is that the engineering rock burst problem is often monitored based on the AE signal in practical engineering. In the PFC model, when the stress between particles is greater than the PB model contact strength, the fracture occurs, that is, an AE hit occurs (Zhang et al, 2018). Therefore, the acoustic emission phenomenon can be simulated by writing fish language to monitor the fracture of the model.…”

Analysis of Acoustic Emission Characteristics and Damage Constitutive Model of Coal-Rock Combined Body Based on Particle Flow Code

“…Therefore, before numerical simulation, PFC meso-parameters need to be adjusted to obtain macro-parameters which are close to the macro-parameters of experimental data. Owing to the limitation of the laboratory test condition, the meso-parameters of numerical rock specimens (Table 1) provided by Zhang et al [22] and the meso-parameters of numerical coal specimens (Table 2) provided by Wang et al [23] were used in this paper to simulate coal-rock combined bodies. In their articles, they compared the stress-strain curves and failure modes of real rock specimen and real coal specimen with numerical rock and coal mass, as shown in Figures 2 and 3.…”

“…Acoustic emission originates from crack propagation in the coal-rock mass and for PFC numerical coal-rock models, the crack propagation is based on "bond breakages". In the process of compression, the parallel bond will break when the stress intensity transmitted between the particles exceeds the bonding strength between the particles [15,22] and a numerical AE event occurs (an AE hits). Note that the numerical acoustic emission of PFC simulation is different from the acoustic emission monitored by the actual test, but there are similarities, which can reflect the destruction process of the material from a mesoscopic perspective [24][25][26][27].…”

“…Comparison of stress-strain curves and failure modes of real rock specimen and PFC rock specimens[22]. (a) Stress-strain curves; (b) Failure modes.…”

Analysis of Internal Stress Distribution and Mechanics Characteristics of Pre-existing Cavity in Brittle Rock Under Triaxial Cyclic Loading

“…In the case of multi-cavity rocks and fracture-hole rocks, Zhang et al (2018) and Fan et al (2018) carried out uniaxial compression tests for the numerical modeling of two circular holes with different angles of the center connection line of the holes. The mechanical behavior and acoustic emission (AE) characteristics of the defective rock materials were analyzed comprehensively, and the damage evolution law was studied.…”