Volumetric and Shear Strain Localization in Mt. Etna Basalt

McBeck, Jessica; Cordonnier, B.; Vinciguerra, Sergio; Renard, François

doi:10.1029/2018gl081299

Cited by 20 publications

(33 citation statements)

References 29 publications

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“…The evolving statistics of the populations of dilatational, contractive and shear strains throughout the triaxial deformation enable comparing the relative importance of these deformation modes among different rock types. non-peer reviewed preprint submitted to EarthArXiv 9 DVC analysis on Fontainebleau sandstone (Renard et al, 2019a) and Mount Etna basalt (McBeck et al, 2019) indicate that shear and dilation dominated the deformation process in these porous rocks under low confining stress (10-20 MPa). The mean of the dilatational strain population increased by larger magnitudes than the shear strain throughout these experiments, suggesting the greater importance of the micromechanisms that produce local dilation rather than shear.…”

Section: Brittle Failure Processes In Rocksmentioning

confidence: 99%

“…Due to the stress-controlled loading, the rock cores fail with a rapid stress drop that prohibits imaging the rock as it supports decreasing axial stress. These experiments have been described in previous studies from our group, including the experiments on Green River shale (McBeck et al, 2018), Fontainebleau sandstone (Renard et al, 2019a), monzonite (Renard et al, 2017(Renard et al, , 2019b, Etna basalt (McBeck et al, 2019) and Anstrude limestone (Renard et al, 2017). The X-ray microtomography data for many of these experiments are available to the community (Renard, 2017(Renard, , 2018a).…”

Section: In Situ X-ray Tomography Experiments Conditionsmentioning

confidence: 99%

“…The strengths of local correlations between each pair of strain components in the examined sub-volumes are similar to each other (Figure 3). The link between shear strain and dilation has been well-recognized in the brittle failure of rocks under triaxial compression (e.g., Hamiel et al, 2004b, Stanchits et al, 2006Tal et al, 2016;McBeck et al, 2019;Renard et al, 2019a,b), and shear strain associated with contraction has been recognized in fewer geologic systems such as cataclastic compaction band development (e.g., Aydin & Johnson, 1983). However, the co-existence of contraction and dilation in small sub-volumes has received less attention (e.g., Renard et al, 2019b).…”

Section: Coincidence Of Strain Modesmentioning

confidence: 99%

“…In particular, we track the mean amplitude and rock volume occupied by four strain components: dilation, contraction, left-lateral shear strain and right-lateral shear strain at each DVC calculation ( Figures 5, S4, 6). Previous work indicates that the evolution of the rock volume occupied by dilation relative to contraction, and the volume occupied by leftlateral relative to right-lateral shear strain, signal approaching macroscopic failure (Renard et al, 2019b;McBeck et al, 2019).…”

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confidence: 97%

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The mixology of precursory strain partitioning approaching brittle failure in rocks

McBeck¹,

Ben‐Zion²,

Raffi³

2020

Preprint

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We examine the strain accumulation and localization process throughout twelve triaxial compression experiments on six rock types deformed in an X-ray transparent apparatus. In each experiment, we acquire 50-100 tomograms of rock samples at differential stress steps during loading, revealing the evolving 3D distribution of X-ray absorption contrasts, indicative of density. Using digital volume correlation (DVC) of pairs of tomograms, we build time series of 3D incremental strain tensor fields as the rocks are deformed toward failure. The Pearson correlation coefficients between components of the local incremental strain tensor at each stress step indicate that the correlation strength between pairs of local strain components, including dilation, contraction and shear strain, are moderate-strong in eleven of twelve experiments. In addition, changes in the local strain components from one DVC calculation to the next show differences in the correlations between pairs of strain components. In particular, the correlation of the local changes in dilation and shear strain tends to be stronger than the correlation of changes in dilation-contraction and contraction-shear strain. In eleven of twelve experiments, the most volumetrically frequent mode of strain accommodation includes a synchronized increase in multiple strain components. Early in loading, under lower differential stress, the most frequent strain accumulation mode involves the paired increase in dilation and contraction at neighboring locations. Under higher differential stress, the most frequent mode is the paired increase in dilation and shear strain. This mode is also the first or second most frequent throughout each complete experiment. Tracking the mean values of the strain components in the sample and the volume of rock that each component occupies reveals fundamental differences in the nature of strain accumulation and localization between the volumetric and shear strain modes. As the dilative strain increases in magnitude throughout loading, it tends to occupy larger volumes within the rock sample and thus delocalizes. In contrast, the increasing shear strain components (left- or right-lateral) do not necessarily occupy larger volume and so involve localization. Consistent with these evolutions, the correlation length of the dilatational strains tends to increase by the largest amounts of the strain components from lower to higher differential stress. In contrast, the correlation length of the shear strains does not consistently increase or decrease with increasing differential stress.

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Section: Brittle Failure Processes In Rocksmentioning

confidence: 99%

Section: In Situ X-ray Tomography Experiments Conditionsmentioning

confidence: 99%

Section: Coincidence Of Strain Modesmentioning

confidence: 99%

mentioning

confidence: 97%

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The mixology of precursory strain partitioning approaching brittle failure in rocks

McBeck¹,

Ben‐Zion²,

Raffi³

2020

Preprint

Self Cite

View full text Add to dashboard Cite

show abstract

“…Digital volume correlation (DVC) analysis was performed to extract the evolution of the displacement field within the sample, using the software Tomowarp2; 40 see also refs ( 41 ) and ( 42 ). DVC analysis cross-correlates voxel intensities in series of tomograms in order to derive the displacement field as a function of time.…”

Section: Materials and Methodsmentioning

confidence: 99%

Real Time 3D Observations of Portland Cement Carbonation at CO₂ Storage Conditions

Panduro

Cordonnier

Gawel

et al. 2020

Environ. Sci. Technol.

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Depleted oil reservoirs are considered a viable solution to the global challenge of CO 2 storage. A key concern is whether the wells can be suitably sealed with cement to hinder the escape of CO 2 . Under reservoir conditions, CO 2 is in its supercritical state, and the high pressures and temperatures involved make real-time microscopic observations of cement degradation experimentally challenging. Here, we present an in situ 3D dynamic X-ray micro computed tomography (μ-CT) study of well cement carbonation at realistic reservoir stress, pore-pressure, and temperature conditions. The high-resolution time-lapse 3D images allow monitoring the progress of reaction fronts in Portland cement, including density changes, sample deformation, and mineral precipitation and dissolution. By switching between flow and nonflow conditions of CO 2 -saturated water through cement, we were able to delineate regimes dominated by calcium carbonate precipitation and dissolution. For the first time, we demonstrate experimentally the impact of the flow history on CO 2 leakage risk for cement plugging. In-situ μ-CT experiments combined with geochemical modeling provide unique insight into the interactions between CO 2 and cement, potentially helping in assessing the risks of CO 2 storage in geological reservoirs.

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Strain localization criteria for viscoplastic geomaterials

Deng

Shahin

Lü

et al. 2022

Num Anal Meth Geomechanics

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This work presents a viscoplastic localization criterion to detect quasi‐instantaneous (i.e., load‐induced) and delayed (creep‐induced) strain localization in rate‐dependent solids. The study is based on the theory of controllability and a viscoplastic description of the mechanical response. Analytical precursors of unstable states are defined through systems of ordinary differential equations (OEDs). The use of the proposed criteria is illustrated at the material point level through a set of strain localization analyses simulating active strain localization of a porous rock. In addition, full‐field finite element simulations of compression tests conducted under various pressures are reported to demonstrate the role of local unstable viscoplasticity in the spontaneous propagation of deformation bands under stationary boundary conditions. The study shows that the viscoplastic localization criterion maintains a negative sign as long as the behavior is unstable, that is, the rate of deformation is accelerating. The sign switch coincides with the transition to decelerating deformation. The analyses revealed that pulses of overstress always emerge in correspondence with the growth of unstable behavior, and the peak matches the transition to stable behavior. The local responses recovered from full‐field analyses were consistent with those observed in analyses at material point level and the predictions of the presented theory.

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Volumetric and Shear Strain Localization in Mt. Etna Basalt

Cited by 20 publications

References 29 publications

The mixology of precursory strain partitioning approaching brittle failure in rocks

The mixology of precursory strain partitioning approaching brittle failure in rocks

Real Time 3D Observations of Portland Cement Carbonation at CO₂ Storage Conditions

Strain localization criteria for viscoplastic geomaterials

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Volumetric and Shear Strain Localization in Mt. Etna Basalt

Cited by 20 publications

References 29 publications

The mixology of precursory strain partitioning approaching brittle failure in rocks

The mixology of precursory strain partitioning approaching brittle failure in rocks

Real Time 3D Observations of Portland Cement Carbonation at CO2 Storage Conditions

Strain localization criteria for viscoplastic geomaterials

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Product

Resources

About

Real Time 3D Observations of Portland Cement Carbonation at CO₂ Storage Conditions