Imaging strain localisation in porous andesite using digital volume correlation

Heap, Michael; Baud, Patrick; McBeck, Jessica; Renard, F.; Carbillet, Lucille; Hall, Stephen A.

doi:10.1016/j.jvolgeores.2020.107038

Cited by 16 publications

(30 citation statements)

References 131 publications

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“…These authors found that the shear band increased in width as a function of increasing strain and that permeability increased by up to three orders of magnitude at inelastic axial strains of about 0.11 (Farquharson et al 2016). Increases in permeability following shear fracture formation were also reported for andesite from Volcán de Colima deformed at an effective pressure of 10 MPa (Heap et al 2020a).…”

Section: Triaxial Deformation Experimentsmentioning

confidence: 80%

“…pore-and crack-filling alteration) can increase strength (e.g. Heap et al 2020a). For example, at a given porosity, the argillic alteration that characterises Pinnacle Ridge at Mt Ruapehu (New Zealand) appears to decrease the strength of andesite (Fig.…”

Section: Factors That Influence the Uniaxial Compressive Strength Of Volcanic Rocksmentioning

confidence: 99%

“…Rizzo et al 2018), no such analysis currently exists for volcanic rocks. Insights into strain localisation in the brittle regime have been recently provided by digital volume correlation analysis performed on X-ray tomographic images (McBeck et al 2019;Heap et al 2020a). McBeck et al (2019) analysed the failure of a low-porosity basalt from Mt Etna deformed under an effective pressure of 10 MPa.…”

Section: Triaxial Deformation Experimentsmentioning

confidence: 99%

“…1a; Louis et al 2007) and that of a typical extrusive volcanic rock (andesite from Volcán de Colima, Mexico; Fig. 1b; Heap et al 2020a). The sandstone, which contains 99% quartz and has a porosity of 0.23 and a grain size of 50-500 μm, has a very homogeneous microstructure in comparison to the andesite, which is characterised by heterogeneously distributed pores of different sizes and shapes and phenocrysts of different types, sizes, and shapes (Fig.…”

Section: Introductionmentioning

confidence: 99%

“…1 (a) Two-dimensional slice extracted from a three-dimensional Xray tomographic image (cubic voxels of width 48.8 μm) of Bentheim sandstone (Germany) (from Louis et al 2007). (b) Two-dimensional slice extracted from a three-dimensional X-ray tomographic image (cubic voxels of width 23 μm) of an andesite from Volcán de Colima (Mexico) (from Heap et al 2020a). The grey level of the voxels corresponds to their density (black = low density; white = high density) risk) or effusive (lower risk) (e.g.…”

Section: Introductionmentioning

confidence: 99%

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The mechanical behaviour and failure modes of volcanic rocks: a review

2021

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The microstructure and mineralogy of volcanic rocks is varied and complex, and their mechanical behaviour is similarly varied and complex. This review summarises recent developments in our understanding of the mechanical behaviour and failure modes of volcanic rocks. Compiled data show that, although porosity exerts a first-order influence on the uniaxial compressive strength of volcanic rocks, parameters such as the partitioning of the void space (pores and microcracks), pore and crystal size and shape, and alteration also play a role. The presence of water, strain rate, and temperature can also influence uniaxial compressive strength. We also discuss the merits of micromechanical models in understanding the mechanical behaviour of volcanic rocks (which includes a review of the available fracture toughness data). Compiled data show that the effective pressure required for the onset of hydrostatic inelastic compaction in volcanic rocks decreases as a function of increasing porosity, and represents the pressure required for cataclastic pore collapse. Differences between brittle and ductile mechanical behaviour (stress-strain curves and the evolution of porosity and acoustic emission activity) from triaxial deformation experiments are outlined. Brittle behaviour is typically characterised by shear fracture formation, and an increase in porosity and permeability. Ductile deformation can either be distributed (cataclastic pore collapse) or localised (compaction bands) and is characterised by a decrease in porosity and permeability. The available data show that tuffs deform by delocalised cataclasis and extrusive volcanic rocks develop compaction bands (planes of collapsed pores connected by microcracks). Brittle failure envelopes and compactive yield caps for volcanic rocks are compared, highlighting that porosity exerts a first-order control on the stresses required for the brittle-ductile transition and shear-enhanced compaction. However, these data cannot be explained by porosity alone and other microstructural parameters, such as pore size, must also play a role. Compactive yield caps for tuffs are elliptical, similar to data for sedimentary rocks, but are linear for extrusive volcanic rocks. Linear yield caps are considered to be a result of a high pre-existing microcrack density and/or a heterogeneous distribution of porosity. However, it is still unclear, with the available data, why compaction bands develop in some volcanic rocks but not others, which microstructural attributes influence the stresses required for the brittle-ductile transition and shear-enhanced compaction, and why the compactive yield caps of extrusive volcanic rocks are linear. We also review the Young’s modulus, tensile strength, and frictional properties of volcanic rocks. Finally, we review how laboratory data have and can be used to improve our understanding of volcanic systems and highlight directions for future research. A deep understanding of the mechanical behaviour and failure modes of volcanic rock can help refine and develop tools to routinely monitor the hazards posed by active volcanoes.

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Section: Triaxial Deformation Experimentsmentioning

confidence: 80%

Section: Factors That Influence the Uniaxial Compressive Strength Of Volcanic Rocksmentioning

confidence: 99%

Section: Triaxial Deformation Experimentsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The mechanical behaviour and failure modes of volcanic rocks: a review

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The influence of heterogeneity on the strength of volcanic rocks and the stability of lava domes

Heap,

Harnett,

Nazarbayov

et al. 2023

Bull Volcanol

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The collapse of lava domes, inherently heterogeneous structures, represents a significant volcanic hazard.Numerical and analogue models designed to model dome instability and collapse have incorporated heterogeneity 2 in the form of discrete zones with homogeneous properties. Based on an assessment of dome rock heterogeneity, we explore whether material property heterogeneity ("diffuse" heterogeneity) within these discrete zones can promote dome instability. X-ray computed tomography shows that dome samples are characterised by high microstructural heterogeneities; e.g., porosity varies from 0.07 to 0.20 over millimetric lengthscales. To explore how microstructural heterogeneity influences sample-scale strength, we performed numerical simulations using Rock Failure and Process Analysis. The mean mechanical properties of the numerical samples were constant, and we introduced heterogeneity by varying their distribution using a Weibull probability function. The models show that increasing heterogeneity can reduce sample-scale strength by more than a factor of two. To explore the influence of dome-scale heterogeneity, we numerically generated lava domes in Particle Flow Code. The domes have the same bulk strength but are characterised by different degrees of heterogeneity by varying the distribution of cohesion using a Weibull probability function. The models show that a greater degree of heterogeneity induces higher dome-scale displacements and that, when there is also a discrete weakened zone, the addition of diffuse heterogeneity leads to more widely distributed deformation. Therefore, alongside discrete zones defined by different material properties, we find that the diffuse heterogeneity inherent to a dome is sufficient to compromise dome stability and should be incorporated in future modelling endeavours.

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Full-field quantification of time-dependent and -independent deformation and fracturing of double-notch flawed rock using digital image correlation

Xue

Zhu

et al. 2021

Geomech. Geophys. Geo-energ. Geo-resour.

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Imaging strain localisation in porous andesite using digital volume correlation

Cited by 16 publications

References 131 publications

The mechanical behaviour and failure modes of volcanic rocks: a review

The mechanical behaviour and failure modes of volcanic rocks: a review

The influence of heterogeneity on the strength of volcanic rocks and the stability of lava domes

Full-field quantification of time-dependent and -independent deformation and fracturing of double-notch flawed rock using digital image correlation

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