Fracture Network Localization Preceding Catastrophic Failure in Triaxial Compression Experiments on Rocks

We quantify the spatial distribution of fracture networks throughout six in situ X-ray tomography triaxial compression experiments on crystalline rocks at confining stresses of 5–35 MPa in order to quantify how fracture development controls the final macroscopic failure of the rock, a process analog...

Descripción completa

Guardado en:

Detalles Bibliográficos
Autores principales:	Jessica McBeck, Yehuda Ben-Zion, François Renard
Formato:	article
Lenguaje:	EN
Publicado:	Frontiers Media S.A. 2021
Materias:	fractures localization X-ray tomography crystalline rock triaxial compression Science Q
Acceso en línea:	https://doaj.org/article/4dd578450ca7488896b35c056976c691
Etiquetas:	Agregar Etiqueta Sin Etiquetas, Sea el primero en etiquetar este registro!

id	oai:doaj.org-article:4dd578450ca7488896b35c056976c691
record_format	dspace
spelling	oai:doaj.org-article:4dd578450ca7488896b35c056976c6912021-12-01T14:06:51ZFracture Network Localization Preceding Catastrophic Failure in Triaxial Compression Experiments on Rocks2296-646310.3389/feart.2021.778811https://doaj.org/article/4dd578450ca7488896b35c056976c6912021-11-01T00:00:00Zhttps://www.frontiersin.org/articles/10.3389/feart.2021.778811/fullhttps://doaj.org/toc/2296-6463We quantify the spatial distribution of fracture networks throughout six in situ X-ray tomography triaxial compression experiments on crystalline rocks at confining stresses of 5–35 MPa in order to quantify how fracture development controls the final macroscopic failure of the rock, a process analogous to those that control geohazards such as earthquakes and landslides. Tracking the proportion of the cumulative volume of fractures with volumes >90th percentile to the total fracture volume, ∑v90/vtot indicates that the fracture networks tend to increase in localization toward these largest fractures for up to 80% of the applied differential stress. The evolution of this metric also matches the evolution of the Gini coefficient, which measures the deviation of a population from uniformity. These results are consistent with observations of localizing low magnitude seismicity before large earthquakes in southern California. In both this analysis and the present work, phases of delocalization interrupt the general increase in localization preceding catastrophic failure, indicating that delocalization does not necessarily indicate a reduction of seismic hazard. However, the proportion of the maximum fracture volume to the total fracture volume does not increase monotonically. Experiments with higher confining stress tend to experience greater localization. To further quantify localization, we compare the geometry of the largest fractures, with volumes >90th percentile, to the best fit plane through these fractures immediately preceding failure. The r2 scores and the mean distance of the fractures to the plane indicate greater localization in monzonite than in granite. The smaller mean mineral diameter and lower confining stress in the granite experiments may contribute to this result. Tracking these various metrics of localization reveals a close association between macroscopic yielding and the acceleration of fracture network localization. Near yielding, ∑v90/vtot and the Gini coefficient increase while the mean distance to the final failure plane decreases. Macroscopic yielding thus occurs when the rate of fracture network localization increases.Jessica McBeckYehuda Ben-ZionFrançois RenardFrançois RenardFrontiers Media S.A.articlefractureslocalizationX-ray tomographycrystalline rocktriaxial compressionScienceQENFrontiers in Earth Science, Vol 9 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	fractures localization X-ray tomography crystalline rock triaxial compression Science Q
spellingShingle	fractures localization X-ray tomography crystalline rock triaxial compression Science Q Jessica McBeck Yehuda Ben-Zion François Renard François Renard Fracture Network Localization Preceding Catastrophic Failure in Triaxial Compression Experiments on Rocks
description	We quantify the spatial distribution of fracture networks throughout six in situ X-ray tomography triaxial compression experiments on crystalline rocks at confining stresses of 5–35 MPa in order to quantify how fracture development controls the final macroscopic failure of the rock, a process analogous to those that control geohazards such as earthquakes and landslides. Tracking the proportion of the cumulative volume of fractures with volumes >90th percentile to the total fracture volume, ∑v90/vtot indicates that the fracture networks tend to increase in localization toward these largest fractures for up to 80% of the applied differential stress. The evolution of this metric also matches the evolution of the Gini coefficient, which measures the deviation of a population from uniformity. These results are consistent with observations of localizing low magnitude seismicity before large earthquakes in southern California. In both this analysis and the present work, phases of delocalization interrupt the general increase in localization preceding catastrophic failure, indicating that delocalization does not necessarily indicate a reduction of seismic hazard. However, the proportion of the maximum fracture volume to the total fracture volume does not increase monotonically. Experiments with higher confining stress tend to experience greater localization. To further quantify localization, we compare the geometry of the largest fractures, with volumes >90th percentile, to the best fit plane through these fractures immediately preceding failure. The r2 scores and the mean distance of the fractures to the plane indicate greater localization in monzonite than in granite. The smaller mean mineral diameter and lower confining stress in the granite experiments may contribute to this result. Tracking these various metrics of localization reveals a close association between macroscopic yielding and the acceleration of fracture network localization. Near yielding, ∑v90/vtot and the Gini coefficient increase while the mean distance to the final failure plane decreases. Macroscopic yielding thus occurs when the rate of fracture network localization increases.
format	article
author	Jessica McBeck Yehuda Ben-Zion François Renard François Renard
author_facet	Jessica McBeck Yehuda Ben-Zion François Renard François Renard
author_sort	Jessica McBeck
title	Fracture Network Localization Preceding Catastrophic Failure in Triaxial Compression Experiments on Rocks
title_short	Fracture Network Localization Preceding Catastrophic Failure in Triaxial Compression Experiments on Rocks
title_full	Fracture Network Localization Preceding Catastrophic Failure in Triaxial Compression Experiments on Rocks
title_fullStr	Fracture Network Localization Preceding Catastrophic Failure in Triaxial Compression Experiments on Rocks
title_full_unstemmed	Fracture Network Localization Preceding Catastrophic Failure in Triaxial Compression Experiments on Rocks
title_sort	fracture network localization preceding catastrophic failure in triaxial compression experiments on rocks
publisher	Frontiers Media S.A.
publishDate	2021
url	https://doaj.org/article/4dd578450ca7488896b35c056976c691
work_keys_str_mv	AT jessicamcbeck fracturenetworklocalizationprecedingcatastrophicfailureintriaxialcompressionexperimentsonrocks AT yehudabenzion fracturenetworklocalizationprecedingcatastrophicfailureintriaxialcompressionexperimentsonrocks AT francoisrenard fracturenetworklocalizationprecedingcatastrophicfailureintriaxialcompressionexperimentsonrocks AT francoisrenard fracturenetworklocalizationprecedingcatastrophicfailureintriaxialcompressionexperimentsonrocks
_version_	1718405055954026496

Fracture Network Localization Preceding Catastrophic Failure in Triaxial Compression Experiments on Rocks

Ejemplares similares