A Method for Multiscale Interpretation of Fracture Processes in Carrara Marble Specimen Containing a Single Flaw Under Uniaxial Compression

Wong, Louis Ngai Yuen; Xiong, Qiquan

doi:10.1029/2018jb015447

Cited by 93 publications

(88 citation statements)

References 43 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Hampton et al [28] categorized AE into shear, tensile, and mixed mode, through manipulating the eigenvalues of the moment tensor matrix. This method has been widely used to identify rock failure under different stress conditions [29][30][31]. Actually, this method was first proposed for an in situ hydrofracturing test [32].…”

Section: Introductionmentioning

confidence: 99%

Micro-Crack Mechanism in the Fracture Evolution of Saturated Granite and Enlightenment to the Precursors of Instability

Dong

Zhang

2020

Sensors

View full text Add to dashboard Cite

To explore the potential precursors of rock instability, it is necessary to clarify the mechanism of micro-crack from fracturing to failure, which involves the evolution of fracture size, orientation, source model, and their relationships to the loading. The waveforms of acoustic emission (AE) recorded by the sensor network attached rock sample during laboratory tests provide a data basis for solving these problems, since these observations are directly related to the characteristics of the fracturing sources. Firstly, we investigated the source mechanism, looking at the rise angle and the average frequency (RA-AF) trends during five loading stages in a uniaxial compression test. Results show that the proportion of shear events significantly increases when approaching instability. Secondly, we calculated the moment tensor for each event, considering the uncertainties of P-wave polarity, azimuth, and the takeoff angles of the rays. Moment tensor solutions suggest that there are obviously more crack events than shear events in all loading stages. Moment tensor evolutions confirmed that the decreasing of isotropic component and the increment of double-couple can be used as precursors of rock fracturing development. Considering the limitations of these two methods, it is suggested that we should be concerned more about the proportions of individual failure components and their evolutions over time, instead of absolutely classifying the events into a certain source type.

show abstract

Section: Introductionmentioning

confidence: 99%

Micro-Crack Mechanism in the Fracture Evolution of Saturated Granite and Enlightenment to the Precursors of Instability

Dong

Zhang

2020

Sensors

View full text Add to dashboard Cite

show abstract

“…e RA (the rise time over the amplitude), AF (the ratio of threshold crossings over the duration of the signal), frequency, amplitude, and signal duration are also the acoustic emission parameters. Analyzing these parameters allows researchers to understand the energy release (amplitude and frequency) [41,[49][50][51] and even the crack failure patterns (RA and AF) [52,53] during the failure process. However, the specimen size has limited effect on the failure patterns of coal and rock [19,[54][55][56], and the overall failure features revealed by these parameters cannot be represented by a single value as fractal dimension and connect the laboratory experiment and the filed work.…”

Section: Scale Effect On the Ae Featuresmentioning

confidence: 99%

Scale Effect on the Anisotropy of Acoustic Emission in Coal

Song

Zhao

Jiang

et al. 2018

Shock and Vibration

View full text Add to dashboard Cite

Acoustic emission (AE) in coal is anisotropic. In this paper, we investigate the microstructure-related scale effect on the anisotropic AE feature in coal at unconfined loading process. A series of coal specimens were processed with diameters of 25 mm, 38 mm, 50 mm, and 75 mm (height to diameter ratio of 2) and anisotropic angles of 0°, 15°, 30°, 45°, 60°, and 90°. The cumulative AE counts and energy dissipation increase with the specimen size, while the energy dissipation per AE count behaves in the opposite way. This may result from the increasing amount of both preexisting discontinuities and cracks (volume/number) needed for specimen failure and the lower energy dissipation AE counts generated by them. The effect of microstructures on the anisotropies of AE weakens with the increasing specimen size. The TRFD and its anisotropy reduce as the specimen size increases, and the reduction of fractal dimension is most pronounced at the anisotropic angle of 45°. The correlation between TRFD and cumulative AE energy in the specimens with different sizes are separately consistent with the negative exponential equation proposed by Xie and Pariseau. With the specimen size gain, the reduction of the TRFD weakens with the increasing amount of cumulative absolute AE energy.

show abstract

“…In this manuscript, we combine AE data analysis advancements in the field of triggering phenomena (Davidsen et al, 2017) into the investigation of the real-time and high-accuracy data collected from rock fracture experiments on specimens containing a single large-scale flaw (Wong & Xiong, 2018). The inclined single open flaw represents an idealized friction-free section of a natural fault (i.e., the creeping aseismic zone such as the San Juan Bautista and Parkfield creeping section of the San Andreas fault), sandwiched by the loading-initiated rock fractures ( Figure 1b).…”

Section: Introductionmentioning

confidence: 99%