Successive cracking steps of a limestone highlighted by ultrasonic wave propagation

Couvreur, J.F.; Vervoort, André; King, M. S.; Lousberg, E.; Thimus, Jean-François

doi:10.1046/j.1365-2478.2001.00242.x

Cited by 15 publications

(12 citation statements)

References 26 publications

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“…This can be further confirmed from the near‐linear relationship between the ε NE AT and the ultrasonic wave amplitude above the CI (Figure b), coherent with the findings of Wulff et al (). This observation is consistent with the studies of Wulff et al (), Couvreur et al (), and Barnhoorn et al (), who found that the changes in ultrasonic signals can be an objective signature of onset (not a precursor) of microcracking in rocks where the damage is diffuse (randomly distributed) and small relative to the ultrasonic wavelength (identical to the scenario in the present study).…”

Section: Resultssupporting

confidence: 94%

Experimental Relationship Between Compressional Wave Attenuation and Surface Strains in Brittle Rock

2019

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Linear ultrasonic testing (LUT) has been extensively used as a tool for the evaluation of damage processes in various materials ranging from synthetic metals to natural geomaterials, such as rocks. A key limitation of LUT‐based damage studies to date is the lack of explicit evidence used in associating material damage with the changes in measured LUT attributes (e.g., ultrasonic wave amplitude and velocity). In this study, the evolution of the full‐field strains in brittle rock specimens (Lyons sandstone) subjected to failure are analyzed in real time and linked with the changes in the ultrasonic wave amplitude in localized areas illuminated by ultrasonic beams, termed as the ultrasonic image areas. The noncontact optical full‐field displacement measurement method of 2‐D digital image correlation is implemented in combination with the LUT procedure to continuously track changes in the ultrasonic wave amplitude with the evolution of strains across the surface of the uniaxially loaded intact rock specimens. The ultrasonic amplitude showed near‐linear correlation with the intensity of inelastic tensile strain recorded in the rock specimens. The results from the study corroborate that the ultrasonic changes are in fact influenced by the regions of tensile cracking, which is the primary inelastic deformation mechanism in brittle rocks.

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Section: Resultssupporting

confidence: 94%

Experimental Relationship Between Compressional Wave Attenuation and Surface Strains in Brittle Rock

2019

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“…The subsequent increase in attenuation in the inelastic regime observed here for all three studied rock types confirms the observation of Couvreur et al (2001) that an increase in attenuation can be attributed to the appearance of new brittle fractures. Here, we have shown consistently that a minimum in attenuation occurs at the onset of inelastic deformation.…”

Section: Discussionsupporting

confidence: 90%

“…The formation of new fractures beyond the elastic limit generally decreases the wave velocity (Hadley, 1976;Granryd et al 1983;Yukutake, 1989;Sayers, 2002a;Fortin et al, 2007;Eslami et al, 2010;Nicolas et al 2016Nicolas et al , 2017Bonnelye et al, 2017). However, the change in attenuation during the fracturing process beyond the elastic limit has not yet been investigated extensively (Couvreur et al, 2001;Goodfellow et al, 2015); it is the main objective of this study. In analogy to fracture closure, where attenuation generally decreases (Zhubayev et al, 2016), fracture formation should cause an increase in attenuation.…”

Section: Introductionmentioning

confidence: 99%

“…In analogy to fracture closure, where attenuation generally decreases (Zhubayev et al, 2016), fracture formation should cause an increase in attenuation. Indeed, Couvreur et al (2001) measure in a limestone sample a decrease, stabilization, and increase of attenuation with increasing stress, and they relate this effect to pore closure and appearance of cracks. Here, we report an experimental study on shale, limestone, and sandstone samples, in which P-and S-wave velocities and attenuation were measured during an increase in stress and fracture formation until complete failure of the rock samples.…”

Section: Introductionmentioning

confidence: 99%

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Experimental identification of the transition from elasticity to inelasticity from ultrasonic attenuation analyses

et al. 2018

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The transition from recoverable elastic to permanent inelastic deformation is marked by the onset of fracturing in the brittle field. Detection of this transition in materials is crucial to predict imminent failure/fracturing. We have used an ultrasonic pulse transmission method to record the change in waveform across this transition during fracturing experiments. The transition from elastic to inelastic deformation coincides with a minimum in ultrasonic attenuation (i.e., maximum wave amplitude). Prior to this attenuation minimum, the existing microfractures close. After this minimum, new microfractures form and attenuation increases until peak stress conditions, at which point, larger fractures form leading to complete sample failure. In our experiments, velocity changes are not sensitive enough to be indicative for the transition from elastic to inelastic deformation. Analysis of attenuation, not velocity, may thus detect imminent failure in materials. Our results may help detect fracturing in borehole casings or the near-wellbore area, or they may help predict imminent release of energy by seismic rupture.

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“…The link between compressibility and chemical processes made in section 3 must therefore be taken into account while interpreting the present ultrasonic velocity measurements. Crack propagation may also lower elastic wave velocity [ Couvreur et al , 2001], and reactive surface areas lower grain contact stiffness [ Vanorio et al , 2010], which might also explain lower velocity measurements in samples saturated with reactive fluids (Figures 5a and 5b). …”

Section: Discussionmentioning

confidence: 99%

Experimental mechanical and chemical compaction of carbonate sand

Croizé¹,

Bjørlykke²,

Jahren³

et al. 2010

J. Geophys. Res.

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[1] Uniaxial compression tests were conducted on bioclastic sand and crushed calcite crystals. Mechanical and chemical processes were investigated to better quantify petrophysical properties of carbonates and their evolution with burial or during fault zone processes. The grain size was in the range 63-500 mm, and the samples were saturated with water in equilibrium with carbonate, glycol, decane, or air. During loading, effective stress was increased to 32 MPa. Mechanical compaction processes (i.e., grain rearrangement, crushing) could be separated from chemical processes (i.e., pressure solution, subcritical crack growth). P and S waves monitored during the tests showed low velocity in samples saturated with reactive fluids. This suggested that chemical reactions at grain contacts reduced the grain framework stiffness. Creep tests were also carried out on bioclastic sand at effective stress of 10, 20, and 30 MPa. No creep was observed in samples saturated with nonreactive fluids. For all the samples saturated with reactive fluids, strain as a function of time was described by a power law of time with a single exponent close to 0.23. Parameters controlling creep rate were, in order of importance, grain size, effective stress, and water saturation. Microstructural observations showed that compaction of bioclastic carbonate sand occurred both mechanically and chemically. Crack propagation probably contributed to mechanical compaction and enhanced chemical compaction during creep. Experimental compaction showed that compaction of carbonates should be modeled as a function of both mechanical and chemical processes, also at relatively shallow depth and low temperature.

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Successive cracking steps of a limestone highlighted by ultrasonic wave propagation

Cited by 15 publications

References 26 publications

Experimental Relationship Between Compressional Wave Attenuation and Surface Strains in Brittle Rock

Experimental Relationship Between Compressional Wave Attenuation and Surface Strains in Brittle Rock

Experimental identification of the transition from elasticity to inelasticity from ultrasonic attenuation analyses

Experimental mechanical and chemical compaction of carbonate sand

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