Three-dimensional evolution of damage in sandstone Brazilian discs by the concurrent use of active and passive ultrasonic techniques

Zhang, Shihuai; Wu, Shunchuan; Zhang, Guang; Guo, Pei; Chu, Chaoqun

doi:10.1007/s11440-018-0737-3

Cited by 30 publications

(5 citation statements)

References 31 publications

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“…For the difference at the peak point, since PVBM is based on waveform analysis, AE signals are difficult to identify and separate accurately at the peak point, as there are too many waveforms, including the superposition and mutual influence of AE events received in such a short period. These signals are always treated as continuous signals and are cut off forcibly 59 . This difference may be improved by introducing some experimental data processing methods 60 .…”

Section: Discussionmentioning

confidence: 99%

Evaluation of the characterization of acoustic emission of brittle rocks from the experiment to numerical simulation

Xue

Zhai

et al. 2022

Sci Rep

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Acoustic emission (AE) characterization is an effective technique to indirectly capture the failure process of quasi brittle rock. In previous studies, both experiments and numerical simulations were adopted to investigate the AE characteristics of rocks. However, as the most popular numerical model, the moment tensor model (MTM) cannot be constrained by the experimental result because there is a gap between MTM and experiments in principle, signal processing and energy analysis. In this paper, we developed a particle-velocity-based model (PVBM) that enabled direct monitoring and analysis of the particle velocity in the numerical model and had good robustness. The PVBM imitated the actual experiment and could fill in gaps between the experiment and MTM. AE experiments of marine shale under uniaxial compression were carried out, and the results were simulated by MTM. In general, the variation trend of the experimental result could be presented by MTM. Nevertheless, the magnitudes of AE parameters by MTM presented notable differences of more than several orders of magnitude compared with those by the experiment. We sequentially used PVBM as a proxy to analyse these discrepancies and systematically evaluate the AE characterization of rocks from the experiment to numerical simulation, considering the influence of wave reflection, energy geometrical diffusion, viscous attenuation, particle size and progressive deterioration of rock material. The combination of MTM and PVBM could reasonably and accurately acquire AE characteristics of the actual AE experiment of rocks by making full use of their respective advantages.

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Section: Discussionmentioning

confidence: 99%

Evaluation of the characterization of acoustic emission of brittle rocks from the experiment to numerical simulation

Xue

Zhai

et al. 2022

Sci Rep

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“…Considering the fact that microcracks are not evenly distributed within the specimen according to a theoretical distribution pattern, and a more dense distribution would be observed in the severely damaged zone [9,13,19], as the spatial scale decreases, there would be a situation where the crack space contains more densely distributed areas, with a lower share of other spatial regions [20,22]. Therefore, a reduction in spatial scale results in a loss of information about the crack space.…”

Section: Deviation Angles At Different Spatial Scalesmentioning

confidence: 99%

“…AE monitoring was performed on rock failure experiments with different loading methods and paths, and the microcrack distribution results successfully indicated the real rupture location and the coincident damage shape [12][13][14][15][16][17][18]. As a result, the microcracks were found to be more prevalent in severely damaged zones in the laboratory and the field [9].…”

Section: Introductionmentioning

confidence: 99%

Spatial Characterization of Single-Cracked Space Based on Microcrack Distribution in Sandstone Failure

et al. 2023

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To further understand the rock damage zone, an approach based on microcrack distribution was proposed to characterize the crack space of rock specimens in this research. Acoustic emission (AE) technology was utilized on sandstone to obtain the spatial distribution of microcracks in which uniaxial compression forms the single-cracked fracture. The proposed theoretical distribution pattern space (TDPS), 3D convex hull, and the minimum volume enclosing ellipsoid (MVEE) algorithms were adopted to analyze the geometric features of the crack space. It was found that the 3D convex hull method returned the smallest results in both area and volume of the crack space, and the largest results were provided by the proposed TDPS method. The difference between the results of the proposed TDPS method and the MVEE method became smaller after 85%. The deviation angle of the principal axis of the cracked space gradually decreased as the spatial scale decreased, while the other two major axes exhibited a tendency to increase at the 65% scale. The results indicate that a spatial scale from 65% to 85% is a reliable range for the characterization of crack space.

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“…Zigong sandstone represents a low-porosity (6.5%) hard sandstone composed mainly of silicate minerals, which has been systematically tested and investigated under different stress conditions. 8,14,15 Compared with other highly porous sandstones, Zigong sandstone features relatively higher strength and a wider brittle range. 15 It exhibits prominent characteristics of brittle fracturing even under a confining pressure (σ3) of as high as 80 MPa, approximately corresponding to a buried depth of 4 km.…”

Section: Experimental Materials and Experimental Proceduresmentioning

confidence: 99%

Elastoplastic constitutive behavior and strain localization of a low-porosity sandstone during brittle fracturing

Zhang¹,

Guo²,

Wu³

2021

Preprint

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We investigated the elastoplastic behavior and strain localization of the Zigong sandstone (porosity: 6.5%) during brittle fracturing based on two series of axisymmetric compression experiments. The experiments were conducted under various confining pressures (σ3 = 0 ~ 80 MPa). For each confining pressure, the sandstone specimens were deformed under constant axial and circumferential strain rates, respectively. When σ3 < 60 MPa, the sandstone first undergoes stable deformation in the post-peak stage and then loses its stability. Before the emergence of instability, the mechanical behavior is hardly affected by the controlling method. When the confining is larger, the sandstone manifests a stable failure process during the whole loading stage. The observed elastoplastic behavior was described by a two-yield surface constitutive model established in the framework of generalized plastic mechanics. The proposed constitutive model incorporates two quadratic yield functions, as well as two linearly independent plastic potential functions, to honor the shear yield and volumetric dilatancy, respectively. Via the return mapping algorithm, the proposed constitutive model was verified by comparing the numerical results with experimental results. In addition, the two-yield surface constitutive model, which is equivalent to the model proposed by Rudnicki and Rice,1 was applied to localization analysis. Assuming that the onset of localization occurs at peak stress, frictional coefficient μ and dilatancy factor β were determined from experimental data. The variations of both plastic parameters predict the transition of localization mode from pure dilation bands under uniaxial compression to pure shear bands at high confining pressures, which is consistent with the experimental observations.

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Three-dimensional evolution of damage in sandstone Brazilian discs by the concurrent use of active and passive ultrasonic techniques

Cited by 30 publications

References 31 publications

Evaluation of the characterization of acoustic emission of brittle rocks from the experiment to numerical simulation

Evaluation of the characterization of acoustic emission of brittle rocks from the experiment to numerical simulation

Spatial Characterization of Single-Cracked Space Based on Microcrack Distribution in Sandstone Failure

Elastoplastic constitutive behavior and strain localization of a low-porosity sandstone during brittle fracturing

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