Acoustic emission and fluid permeability measurements on thermally cracked rocks

Jones, Callum M. S.; Keaney, Gemma; Meredith, P. G.; Murrell, Stanley A.

doi:10.1016/s0079-1946(97)00071-2

Cited by 59 publications

(30 citation statements)

References 5 publications

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“…However, rock physical properties also deteriorate in a “closed” system, due to thermal microcracking [see also Yavuz et al , 2010, and references therein]. The thermal microcracking within a “closed” system would quickly convert it to an “open” system (since thermal microcracking has been previously shown to dramatically increase permeability, see Jones et al [1997]). Therefore, given time, CO 2 will be quickly and efficiently removed in both scenarios, fuelling decarbonation, and resulting in detrimental changes to rock physical properties.…”

Section: Resultsmentioning

confidence: 99%

Volcanic edifice weakening via decarbonation: A self‐limiting process?

Mollo

Heap

Iezzi

et al. 2012

Geophysical Research Letters

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The inherent instability of volcanic edifices, and their resultant propensity for catastrophic collapse, is a constant source of volcanic risk. Structural instability of volcanic edifices may be amplified by the presence of carbonate rocks in the sub‐volcanic strata, due to the debilitating response of carbonates to thermally‐induced alteration. Nonetheless, decarbonation reactions (the primary weakening mechanism), may stall when the system becomes buffered by rising levels of a reaction product, carbon dioxide. Such thermodynamic stalling might be inferred to serve to circumvent the weakness of volcanic structures. However, the present study shows that, even when decarbonation is halted, rock physical properties continue to degrade due to thermal microcracking. Furthermore, as a result, the pathways for the escape of carbon dioxide are numerous within a volcanic edifice. Therefore, in the case of an edifice with a sub‐volcanic sedimentary basement, the generation of carbon dioxide via decarbonation is unlikely to hinder its impact on instability, and thus potentially devastating flank collapse.

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Section: Resultsmentioning

confidence: 99%

Volcanic edifice weakening via decarbonation: A self‐limiting process?

Mollo

Heap

Iezzi

et al. 2012

Geophysical Research Letters

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“…Porosity also controls the mechanical response of materials whereby their strength decreases and elasticity increases with porosity (e.g., Al-Harthi et al, 1999;Spieler et al, 2004;Paterson and Wong, 2005;Heap et al, 2014a,b). Thermal stressing of rock has also been argued to affect its strength, although damage imparted by thermal cracking has been shown to lead to unsystematic changes in mechanical response (Jones et al, 1997;Rocchi et al, 2003;Balme et al, 2004;Kendrick et al, 2013a;Heap et al, 2014a); the ambiguity of this claim has been linked to the extent of pre-existing microcrack damage in a rock (Vinciguerra et al, 2005;Heap et al, 2014a). Other rocks can debilitate upon thermal stressing, as is the case during decarbonation and dehydroxylization (Heap et al, 2012) of certain rock-forming minerals.…”

Section: Introductionmentioning

confidence: 99%

Geomechanical rock properties of a basaltic volcano

et al. 2015

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In volcanic regions, reliable estimates of mechanical properties for specific volcanic events such as cyclic inflation-deflation cycles by magmatic intrusions, thermal stressing, and high temperatures are crucial for building accurate models of volcanic phenomena. This study focuses on the challenge of characterizing volcanic materials for the numerical analyses of such events. To do this, we evaluated the physical (porosity, permeability) and mechanical (strength) properties of basaltic rocks at Pacaya Volcano (Guatemala) through a variety of laboratory experiments, including: room temperature, high temperature (935 • C), and cyclically-loaded uniaxial compressive strength tests on as-collected and thermally-treated rock samples. Knowledge of the material response to such varied stressing conditions is necessary to analyze potential hazards at Pacaya, whose persistent activity has led to 13 evacuations of towns near the volcano since 1987. The rocks show a non-linear relationship between permeability and porosity, which relates to the importance of the crack network connecting the vesicles in these rocks. Here we show that strength not only decreases with porosity and permeability, but also with prolonged stressing (i.e., at lower strain rates) and upon cooling. Complimentary tests in which cyclic episodes of thermal or load stressing showed no systematic weakening of the material on the scale of our experiments. Most importantly, we show the extremely heterogeneous nature of volcanic edifices that arise from differences in porosity and permeability of the local lithologies, the limited lateral extent of lava flows, and the scars of previous collapse events. Input of these process-specific rock behaviors into slope stability and deformation models can change the resultant hazard analysis. We anticipate that an increased parameterization of rock properties will improve mitigation power.

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“…Acoustic emission (AE) is a phenomenon of ultrasonic or acoustic wave emission occurring dining fracture formation, without finite destruction of the material (Jones et al 1997;Zietlow & Labuz 1998). Elastic waves from acoustic emission are characterized by the frequency of emitted waves (F) with activity A (the number of events per time unit), intensity I (energy characteristic of a separate event) and some other particular features.…”

Section: Acoustic Emission Datamentioning

confidence: 99%

Deformation of metavolcanics in the Karachay Lake area, Southern Urals: petrophysical and mineral-chemical aspects

Петров

Poluektov

Zharikov

et al. 2005

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This paper is the result of laboratory tests aimed at comparative assessment of the filtration, elastic and mechanical properties of metavolcanics, as well as a preliminary investigation of the nature of characteristic variations in P-T parameters, simulating the conditions in the vicinity of an underground storage facility for heat-generating radioactive waste. The properties have been studied in cores collected from the deepest (1200 m) hole in the metavolcanics, focusing on intervals subjected to different strain intensities. Interpretation of the data obtained suggests that the identification of the most probable pathways for fluid flow and radionuclide transport depends on estimates of the retardation characteristics of zones of disjunctive dislocation. However, the widespread occurrence of linear zones of schistosity, mylonitization and brecciation may not be a decisive negative factor in the long-term performance assessment of the underground storage facility, because these minerals, which concentrate radionuclides such as epidote, chlorite, sericite, and Fe oxyhydroxides are widely distributed in these zones. Moreover, open microfractures and pores affected by heat will be filled with neoformed minerals (epidote, chlorite, carbonate) characterized by high sorption capacity with respect to radionuclides, due to release of intergranular water, as well as carbonatization reactions. Simultaneously, the system of open macro-and microfractures that resulted from stress affecting relatively undisturbed blocks may be one of the factors dramatically reducing country rock retention capability. Therefore, the results of petrophysical and mineral-chemical investigations must be taken into account in feasibility studies of designs for the construction of underground systems for final disposal of high-level wastes and/or long-term storage of spent nuclear fuel in the PA Mayak area.

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Acoustic emission and fluid permeability measurements on thermally cracked rocks

Cited by 59 publications

References 5 publications

Volcanic edifice weakening via decarbonation: A self‐limiting process?

Volcanic edifice weakening via decarbonation: A self‐limiting process?

Geomechanical rock properties of a basaltic volcano

Deformation of metavolcanics in the Karachay Lake area, Southern Urals: petrophysical and mineral-chemical aspects

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