A Directional Crack Damage Memory Effect in Sandstone Under True Triaxial Loading

Browning, John; Meredith, P. G.; Stuart, C.; Harland, Sophie; Healy, David; Mitchell, Thomas M.

doi:10.1029/2018gl078207

Cited by 29 publications

(20 citation statements)

References 23 publications

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“…It also corresponds to the nonlinearity D threshold, at about 90% of the previous maximum stress. This result has been recognized in previous studies (Browning et al, 2018;Holcomb, 1993;Kaiser, 1953;Lavrov, 2003;Lockner, 1993) and is known as the Kaiser effect.…”

Section: Direct Measurements: Mechanical Data Wave Velocities and Aessupporting

confidence: 69%

Development and Recovery of Stress‐Induced Elastic Anisotropy During Cyclic Loading Experiment on Westerly Granite

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Pimienta

Faulkner

et al. 2018

Geophysical Research Letters

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In the upper crust, where brittle deformation mechanisms dominate, the development of crack networks subject to anisotropic stress fields generates stress‐induced elastic anisotropy. Here a rock specimen of Westerly granite was submitted to differential stress cycles (i.e., loading and unloading) of increasing amplitudes, up to failure and under upper crustal conditions. Combined records of strains, acoustic emissions, and P and S elastic wave anisotropies demonstrate that increasing differential stress promotes crack opening, sliding, and propagation subparallel to the main compressive stress orientation. However, the significant elastic anisotropies observed during loading (≥20%) almost vanish upon stress removal, demonstrating that in the absence of stress, crack‐related elastic anisotropy remains limited (≤10%). As a consequence, (i) crack‐related elastic anisotropies measured in the crust will likely be a strong function of the level of differential stress, and consequently (ii) continuous monitoring of elastic wave velocity anisotropy along faults could shed light on the mechanism of stress accumulation during interseismic loading.

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Section: Direct Measurements: Mechanical Data Wave Velocities and Aessupporting

confidence: 69%

Development and Recovery of Stress‐Induced Elastic Anisotropy During Cyclic Loading Experiment on Westerly Granite

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Pimienta

Faulkner

et al. 2018

Geophysical Research Letters

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“…Browning et al (2017) expanded on this observation to suggest that it is not the individual stress state that controls the AE onset level but instead the crack damage state, and hence, the Kaiser effect is actually a damage memory effect rather than a stress memory effect. Browning et al (2018) used a true‐triaxial apparatus to extend this observation further and suggest that materials can exhibit multiple damage memories depending on the relative orientations of the principal stresses and also the stressing history. As such, mechanical cyclic loading is relatively well studied and understood.…”

Section: Introductionmentioning

confidence: 97%

“…For example, brittle materials such as rocks commonly exhibit a stress memory effect, or so‐called Kaiser effect , when cyclically deformed through mechanical loading (Browning et al, 2018; Holcomb, 1993; Kaiser, 1953; Lavrov, 2001, 2003; Lockner, 1993). This effect has been shown both in laboratory‐scale rock samples (e.g., Browning et al, 2018; Heap et al, 2009) and also on the scale of kilometers regionally in parts of Iceland (Heimisson et al, 2015). Manifestation of the Kaiser effect is most commonly discerned through monitoring the output of microseismicity or acoustic emissions (AEs) as a proxy for induced crack damage.…”

Section: Introductionmentioning

confidence: 99%

Microstructural Controls on Thermal Crack Damage and the Presence of a Temperature‐Memory Effect During Cyclic Thermal Stressing of Rocks

Daoud

Browning

Meredith

et al. 2020

Geophysical Research Letters

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We present results from a series of thermal stressing experiments that used three igneous rocks of different composition, grain size, and origin and contemporaneously recorded acoustic emissions (AEs) with changing temperature. Samples were subjected to both a single heating and cooling cycle and multiple heating/cooling cycles to different peak temperatures. The vast majority of thermal crack damage is generated during heating in the coarser-grained (quartz rich) rock but during cooling in the two finer-grained (quartz poor) rocks. Our AE results also demonstrate the presence of a temperature-memory effect, analogous to the Kaiser stress-memory effect observed during cyclic mechanical loading, but only in the coarser-grained rock. We suggest that the total amount of crack damage induced during either heating or cooling is dependent on the mineral composition and, most importantly, the grain size and arrangement, as well as the maximum temperature to which the rock was exposed. We use our laboratory-scale results to suggest ways in which crustal-scale geophysical data may need to be reinterpreted to provide more accurate estimates of total, accumulated damage and the approach to macroscopic failure in crustal segments hosting magma chambers and geothermal reservoirs. Plain Language Summary We present results from a series of laboratory thermal stressing experiments using three igneous rocks of different composition, grain size, and origin: a Granophyre (SGP) from the Slaufrudalur pluton in Iceland, an Andesite from Santorini, Greece (SA), and a Basalt from the Seljadalur region of Iceland (SB), in which acoustic emissions (AEs) were recorded at the same time as the temperature of the samples was experimentally increased or decreased. Samples were subjected to both a single heating and cooling cycle and multiple heating and cooling cycles to different peak temperatures. The vast majority of thermal crack damage was generated during heating in the larger-grained SGP but during cooling in the smaller-grained SA and SB. Our AE results demonstrate the presence of a temperature-memory effect in SGP, analogous to the Kaiser stress-memory effect observed during cyclic mechanical loading, but no similar effect is observed in either SA or SB. We suggest that the total amount of crack damage is dependent on the mineral composition and, most importantly, the grain size and arrangement, as well as the maximum temperature to which the rock was exposed. The results should be considered in models that consider the distribution of damage in cyclically thermally stressed regions such as crustal segments hosting geothermal reservoirs and/or magmatic intrusions.

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“…15, we plot the fluid velocity field in several orientations although the fracture network that creates the permeability is assumed to be isotropic. This is a limitation that we seek to investigate further in the future as it is well known that fault zones in complex tectonic regimes may be overprinted with anisotropic fracture networks (e.g., Browning et al, 2018).…”

Section: Thermal Numerical Modeling Setupmentioning

confidence: 99%

Thermal fluid circulation around the Karliova triple junction: Geochemical features and volcano-tectonic implications (Eastern Turkey)

et al. 2019

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The Karlıova triple junction (KTJ) in eastern Turkey has been subjected to incremental deformation resulting in complex kinematic and mechanical interactions throughout the upper crust. These interactions have generated tectonic inversions and uplift, extensive seismicity and volcanism. The regional tectonics generate local stresses, some of which are favorable to magma transport and thermal water circulation throughout the lithosphere. Here we evalauate hydrogeochemical, geological and numerical results relating to the mechanism of thermal fluid circulation around the KTJ. Hydrogeochemistry of the samples indicates that the thermal water springs are probably heated by steam. Volcanic rocks at the site appear to be the host rock owing to the enrichment of Na + and Cl − ions in water and the abundance of these elements in minerals of the volcanic rocks. In addition, it is clear that the thermal fluids are sourced from depth and migrate through permeable networks of faults. The effects of crustal heterogeneities, in particular the geometry and mechanical properties of many faults and layers, on thermal fluid circulation in relation to active magma chambers were investigated under a variety of different mechanical conditions. The numerical results indicate very close relationships between the stress field causing faulting and thermal fluid movement in the KTJ. The effect of thermal transfer was modeled with depth throughout the crust and along the the crustal surface. The models show that some faults encourage thermal fluid circulation below the Varto and Özenç volcanoes. Hydrogeochemical, geological and numerical results suggest that magmas residing beneath both the Varto caldera and the Özenç volcano are the main heat source for thermal fluid in the Varto region. Fluid-solid interactions and fluid circulation models show that the permeable faults are important factors affecting heat transport and fluid circulation. In a series of thermal fluid flow models we probe the mechanism for fluid and gas transport from the 900°C 'hot' zone around the deep magma chambers and investigate how heat is lost throughout the crust on the way to the surface and so eventually creates water channels of temperatures between 50 to 60°C.

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A Directional Crack Damage Memory Effect in Sandstone Under True Triaxial Loading

Cited by 29 publications

References 23 publications

Development and Recovery of Stress‐Induced Elastic Anisotropy During Cyclic Loading Experiment on Westerly Granite

Development and Recovery of Stress‐Induced Elastic Anisotropy During Cyclic Loading Experiment on Westerly Granite

Microstructural Controls on Thermal Crack Damage and the Presence of a Temperature‐Memory Effect During Cyclic Thermal Stressing of Rocks

Thermal fluid circulation around the Karliova triple junction: Geochemical features and volcano-tectonic implications (Eastern Turkey)

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