Microscale characterization of rupture nucleation unravels precursors to faulting in rocks

Renard, François; Cordonnier, B.; Kobchenko, Maya; Kandula, Neelima; Weiss, Jérôme; Zhu, Wenlu

doi:10.1016/j.epsl.2017.08.002

Cited by 75 publications

(68 citation statements)

References 33 publications

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“…Optical microscopy (Moore & Lockner, ; Tapponnier & Brace, ), scanning electron microscopy (Brace et al, ), laser scanning confocal microscopy (Fredrich et al, ), and acoustic emissions (Lockner et al, ) have revealed some of the microstructural origins of precursors prior to macroscopic failure. Complementary to these techniques, dynamic X‐ray microtomography coupled with triaxial load cell is a unique tool for imaging the microstructure of crustal rocks that are subjected to deformation (e.g., Renard et al, ; Renard, Mcbeck, et al, ; Renard, Weiss, et al, ; Iglauer & Lebedev, ). This technique provides three‐dimensional microstructural information on damage distribution as failure is approached and is complementary to other imaging techniques such as acoustic emissions (e.g., Renard, McBeck, et al, ).…”

Section: Introductionmentioning

confidence: 99%

Dynamics of Microscale Precursors During Brittle Compressive Failure in Carrara Marble

et al. 2019

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Microscale heterogeneities influence failure mechanisms in the crust. To track the microstructural changes in rock samples when loaded until failure, we employed a novel experimental technique that couples dynamic X‐ray microtomography imaging with a triaxial deformation apparatus. We studied the brittle failure of Carrara marble under triaxial compression. Dynamic tomographic data revealed the spatial organization of microfractures and damage increments characterizing the precursory activity toward catastrophic failure. We quantified the emergence of scaling relationships between microstructural parameters, including total damage volume, incremental damage volume, the largest connected microfracture, and the applied differential stress. The total volume of microfractures accumulated from the beginning of the experiment as well as the incremental damage showed power law increase. The growth of the largest connected microfracture was related to differential stress as a power law with divergence at failure. The microfracture volume increments were distributed according to a power law with an upper cutoff that itself spanned the entire volume toward failure. These characteristic features of brittle failure in Carrara marble under compression are in agreement with theoretical models that consider failure as a critical phase transition. We also observed that, very close to failure, several power law relationships broke down, which we interpret to be related to the coalescence of the largest microfractures in a finite size volume. Scaling laws and associated exponents computed from our data are compared with predictions made from theoretical and numerical models. Our results show that precursors of macroscopic brittle failure in Carrara marble follow predictable trends.

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Section: Introductionmentioning

confidence: 99%

Dynamics of Microscale Precursors During Brittle Compressive Failure in Carrara Marble

et al. 2019

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“…Advances in time‐resolved three‐dimensional microtomography imaging (e.g., Renard et al, , ) and three‐dimensional digital volume correlation (DVC) analysis (e.g., Tudisco et al, ) enable in situ investigations of deformation processes via quantification of shear and volumetric strains within rocks and other materials. In this study, we aim to better understand fracture development within mechanically anisotropic shale and characterize the transition from diffuse deformation to strain localization and the propagation of and slip along shear fractures.…”

Section: Introductionmentioning

confidence: 99%

Investigating the Onset of Strain Localization Within Anisotropic Shale Using Digital Volume Correlation of Time‐Resolved X‐Ray Microtomography Images

et al. 2018

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Digital volume correlation analysis of time‐resolved X‐ray microtomography scans acquired during in situ triaxial compression of Green River shale cores provided time series of 3‐D incremental strain fields that elucidated evolving deformation processes by quantifying microscopic strain localization. With these data, we investigated the impact of mechanical anisotropy on microscopic strain localization culminating in macroscopic shear failure. We conducted triaxial compression experiments with the maximum compressive stress, σ1, aligned perpendicular and parallel to lamination planes in order to investigate end‐member stress states that arise within sedimentary basins. When the preexisting laminations were perpendicular to σ1, a lamination‐parallel region with high axial compaction developed within the macroscopically linear deformation phase of the experiment and then thickened with increasing applied differential stress. Scanning electron microscopy images indicate that this axial compaction occurred within a lower density lamination and that more axial compaction occurred within the center of the core than near its sides. Boundary element method simulations suggest that this compacting volume promoted shear fracture development within the upper portion of the shale. When the laminations were parallel to σ1, lamination‐parallel dilation bands formed, thickened, and intensified in dilation. Population densities of the distributions of incremental shear strain, radial dilation, and axial contraction calculated by digital volume correlation analysis enabled quantification of the evolving overall impact of, and interplay between, these various deformation modes.

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“…Similarities in the mode of fault development are observed for low (5 MPa) and intermediate (15 MPa) effective pressures: Pervasive tensile cracking initially affects the samples; subsequent interlinking reflects the formation crack clusters, which then coalesce to form the final shear plane. At relatively high effective pressure (30 MPa), cracks parallel to the applied main compressive stress ( σ 1 ) mostly form along a well‐developed plane; then rapid linkage localizes the fault along a finite‐size process zone (Reches & Lockner, ; Renard et al, ).…”

Section: Discussionmentioning

confidence: 99%

“…High-resolution BSE images allowed us to study fault initiation over a significant area within samples deformed under a range of effective pressures (from 5 to 30 MPa; Figure 4). ), cracks parallel to the applied main compressive stress ( 1 ) mostly form along a well-developed plane; then rapid linkage localizes the fault along a finite-size process zone (Reches & Lockner, 1994;Renard et al, 2017).…”

Section: Discussionmentioning

confidence: 99%

Detecting the Onset of Strain Localization Using Two‐Dimensional Wavelet Analysis on Sandstone Deformed at Different Effective Pressures

et al. 2018

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Laboratory brittle deformation experiments have shown that a rapid transition exists in the behavior of porous materials under stress: At a certain point, early formed and spatially distributed tensile cracks interact and coalesce forming a shear plane. In this work, we present and apply a novel image processing tool that is able to quantify this transition between distributed (“stable”) damage accumulation and localized (“unstable”) deformation, in terms of the size, density, and orientation of cracks at the point of strain localization. Our technique, based on a two‐dimensional Morlet wavelet analysis, can recognize, extract, and visually separate the multiscale changes occurring in the crack network during the deformation process. We first performed a series of triaxial experiments (σ1>σ2=σ3) on core plugs of Hopeman Sandstone (Scotland, UK) at different effective pressures (from 5 to 30 MPa). We then processed high‐resolution backscattered electron microscope images of thin sections of these core plugs and found differences in the strain localization process as effective pressure was increased. The critical length of tensile cracks required before the onset of strain localization was reduced from 0.24 to 0.15 mm as the effective pressure was increased to 30 MPa, resulting in a narrow fracture zone. Critically, by comparing patterns of fractures in these deformed sandstone samples, we can quantitatively explore the relationship between the observed geometry of the cracks and the inferred mechanical processes. This will eventually help us to better understand the physics underlying the initiation of catastrophic events, such as earthquakes, landslides, and volcanic eruptions.

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Microscale characterization of rupture nucleation unravels precursors to faulting in rocks

Cited by 75 publications

References 33 publications

Dynamics of Microscale Precursors During Brittle Compressive Failure in Carrara Marble

Dynamics of Microscale Precursors During Brittle Compressive Failure in Carrara Marble

Investigating the Onset of Strain Localization Within Anisotropic Shale Using Digital Volume Correlation of Time‐Resolved X‐Ray Microtomography Images

Detecting the Onset of Strain Localization Using Two‐Dimensional Wavelet Analysis on Sandstone Deformed at Different Effective Pressures

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