scholarly journals Microscopic Failure Mechanism Analysis of Rock Under Dynamic Brazilian Test Based on Acoustic Emission and Moment Tensor Simulation

2021 ◽  
Vol 8 ◽  
Author(s):  
Zilong Zhou ◽  
Jing Zhou ◽  
Yuan Zhao ◽  
Lianjun Chen ◽  
Chongjin Li
Keyword(s):  
Acoustic Emission ◽  
Failure Mechanism ◽  
Failure Mode ◽  
Moment Tensor ◽  
Brazilian Test ◽  
Mechanism Analysis ◽  
Micro Cracks ◽  
Moment Tensor Analysis ◽  
Simulation Results ◽  
The Moment

The dynamic tensile failure of rock is a main failure mode in deep underground engineering projects. The microscopic failure mechanism analysis of this failure mode plays a key role in dynamic disaster warning. Moment tensor inversion is a very well-known method used to analyze failure mechanisms. However, an acoustic emission (AE) event cannot be accurately distinguished in rock dynamic experiments at the laboratory scale, because there are hundreds of AE events generated within a few hundred microseconds in one dynamic test. Therefore, moment tensor analysis is rarely applied in rock dynamic tests with laboratory scale. In this paper, AE and moment tensor simulations with the discrete element method (DEM) are introduced to analyze the microscopic failure mechanism of rock under a dynamic Brazilian test. Comparing the simulation results of AE and moment tensor analysis with the simulation results of micro-crack with DEM, the moment tensor discriminant method can obtain the mechanical mechanism and energy level of micro-cracks. Furthermore, R, which is the ratio of isotropic and deviatoric components of the moment tensor, is used to analyze the AE source mechanism. The implosion, shear, and tensile of the AE source mechanism can better explain the evolution process of main axial crack and the shear failure zones of the Brazilian disc specimen under dynamic tensile simulation. These findings contribute to a better understanding of the microscopic failure mechanism of rock under a dynamic tensile test than the statistical types of micro-cracks based on break bonds with DEM.

scholarly journals Research on Multijoint Rock Failure Mechanism Based on Moment Tensor Theory

2020 ◽  
Vol 2020 ◽  
pp. 1-17
Author(s):  
J. F. Chai
Keyword(s):  
Acoustic Emission ◽  
Failure Mechanism ◽  
Moment Tensor ◽  
Spatial Location ◽  
Rock Failure ◽  
Particle Flow Code ◽  
Emission Data ◽  
Diagram Method ◽  
Tensor Theory ◽  
The Moment

To reveal the influence of the number and location of joints on rock failure mechanism, using Particle Flow Code (PFC) to simulate the calculation of a large amount of acoustic emission data generated during breeding, development, and penetration of rock cracks, the fracture parameters such as the spatial location, rupture azimuth, rupture type, stress state, and moment magnitude of acoustic emission events in various fracture stages of multijoint rock were studied based on the moment tensor theory, the P-T diagram method, and the T-k diagram method. It will be of great importance in the geotechnical engineering field.

Uncertainty in FPSs from moment-tensor inversion

Geophysics ◽  
2011 ◽  
Vol 76 (6) ◽  
pp. WC65-WC75 ◽  
Author(s):  
Jing Du ◽  
Norm R. Warpinski
Keyword(s):  
Moment Tensor ◽  
Failure Process ◽  
Uncertainty Propagation ◽  
Moment Tensor Inversion ◽  
Hydraulic Fractures ◽  
Mechanism Analysis ◽  
Fault Plane Solutions ◽  
Waveform Data ◽  
Amplitude Data ◽  
The Moment

Although microseismic monitoring of hydraulic fractures has primarily been concerned with the dimensions, complexity, and growth of fractures or fracture systems, there is an ever-increasing desire to extract more information about the hydraulic-fracturing and/or natural fractures from microseismic data. Source mechanism analysis, which is concerned with deducing details of the failure process from the microseismic waveform data, is, therefore, attracting more attention. However, most of the studies focus more on the moment-tensor inversion than on extracting fault-plane solutions (FPSs) from inverted moment tensors. The FPSs can be extracted from the inverted moment-tensor, but there remains a question regarding how errors associated with the inversion of the moment-tensor affect the accuracy of the FPSs. We examine the uncertainties of FPS, given the uncertainties of the amplitude data, by looking into the uncertainty propagation from amplitude data into the moment-tensor and then into the resultant FPS. The uncertainty propagation method will be demonstrated using two synthetic examples.

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