The fate and transport of metals and volatile organic compounds at two field sites were observed ... more The fate and transport of metals and volatile organic compounds at two field sites were observed and characterized at the coastline and the hyporheic zone. Metal concentrations were determined at West Neck Bay, both at the coastline and up to 90 ft offshore. Qualitatively, it appears that the groundwater discharging into West Neck Bay is composed of three components. These components result from groundwater originating near the coast, at a landfill approximately 1200 ft upgradient, and from residential areas further inland on Shelter Island. Comparison with an analytical flow net indicates that these observations cannot be explained by advective transport alone, and it is likely that colloidal transport plays a major role in the study area. Naphthalene concentrations entering Lawrence Creek in Bayshore, NY were also determined and a methodology is introduced at that site for determining contaminant or nutrient fluxes into a coastal environment.
Shelter Island draws all of its water from a thin wedge (with an average thickness of ~ 80’) of t... more Shelter Island draws all of its water from a thin wedge (with an average thickness of ~ 80’) of the anisotropic and unconfined Upper Glacial aquifer, that is surrounded on all sides and below by saline groundwater. Consequently, the aquifer is vulnerable to contamination, mainly salt water intrusion that may be aggravated by well pumping near the coast. In order to assess and manage threats to the water supply, such as chemical contamination and salt water intrusion, it is necessary to understand the nature of groundwater flow and its interplay with coastal dynamics in the region. The overall objective of this study is to construct a 3-dimensional, finite-difference model of the groundwater flow for the coastal areas of Shelter Island using the MODFLOW code. The prediction of a numerical model is sensitively dependent on the boundary conditions. For a steady flow model, it is necessary to prescribe the spatial extent and recharge of the contributing area, and the spatial extent of t...
International Journal of Rock Mechanics and Mining Sciences, 2018
In Fontainebleau sandstone, the evolution of transport properties with porosity is related to cha... more In Fontainebleau sandstone, the evolution of transport properties with porosity is related to changes in both the size and connectivity of the pore space. Microcomputed tomography can be used to characterize the relevant geometric attributes, with the resolution that is sufficiently refined for realistic simulation of transport properties based on the 3D image. In this study, we adopted a hybrid computation scheme that is based on a hierarchical multi-scale approach. The specimen was partitioned into cubic sub-volumes for pore-scale simulation of hydraulic permeability and formation factor using the lattice Boltzmann method. The pore-scale results were then linked with finite element simulation in a homogenized scheme to compute and upscale the transport properties to specimen scale. The simulated permeability and formation factor have magnitude and anisotropy that are in good agreement with experimental rock physics data. Together with simulated and measured values of connected porosity and specific surface area, they provide useful insights into how pore geometry controls the evolution of the transport properties.
We present a SE(3)-equivariant graph neural network (GNN) approach that directly predicting the f... more We present a SE(3)-equivariant graph neural network (GNN) approach that directly predicting the formation factor and effective permeability from micro-CT images. FFT solvers are established to compute both the formation factor and effective permeability, while the topology and geometry of the pore space are represented by a persistence-based Morse graph. Together, they constitute the database for training, validating, and testing the neural networks. While the graph and Euclidean convolutional approaches both employ neural networks to generate low-dimensional latent space to represent the features of the micro-structures for forward predictions, the SE(3) equivariant neural network is found to generate more accurate predictions, especially when the training data is limited. Numerical experiments have also shown that the new SE(3) approach leads to predictions that fulfill the material frame indifference whereas the predictions from classical convolutional neural networks (CNN) may suffer from spurious dependence on the coordinate system of the training data. Comparisons among predictions inferred from training the CNN and those from graph convolutional neural networks (GNN) with and without the equivariant constraint indicate that the equivariant graph neural network seems to perform better than the CNN and GNN without enforcing equivariant constraints.
Dilatancy is universally observed as a precursor of brittle faulting in geomaterials. Laboratory ... more Dilatancy is universally observed as a precursor of brittle faulting in geomaterials. Laboratory data on permeability of triaxially compressed rocks indicate that its evolution during deformation can be very complex. In low-porosity crystalline rocks, permeability enhancement is generally observed during dilatancy and a positive correlation exists between permeability and porosity. In porous siliciclastic rocks, experimental data show that the permeability would actually decrease while the pore space dilates as a sample is stressed to brittle failure. With constraints from microstructural observations, percolation network models provide physical insights into the interplay of stress-induced cracking and pre-existing pore structure that induces such negative correlation between porosity and permeability changes. The laboratory data suggest that tectonic deformation in a seismogenic system located in crystalline rock can potentially induce massive fluid discharge along conduits, which may be localized in a high-permeability heterogeneity such as the damage zone. However, it is unlikely that faulting in porous rock formations and shear displacement along gouge zones can provide conduits for fluid along fault zones. To emphasize the fundamental differences between a compact and a porous rock, separate deformation-permeability maps in the stress space are proposed as conceptual models for the permeability evolution. In a region of active faulting, the loading path typically involves variations in the deviatoric stresses, as well as the mean stress and pore pressure. Laboratory data provide important insight into the interplay of deviatoric stresses, mean stress, and pore pressure in relation to permeability evolution and fluid transport. Hydromechanical parameters that control the generation and maintenance of pore pressure excess are also identified.
HAL (Le Centre pour la Communication Scientifique Directe), Jun 25, 2011
HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
Geological Society, London, Special Publications, 2007
Crack and textural fabrics have significant control over the development of mechanical anisotropy... more Crack and textural fabrics have significant control over the development of mechanical anisotropy in a rock. Bedding in sedimentary rocks, cleavage in slates, preferred orientation of anisotropic minerals and anisotropic distribution of microcracks can all contribute to elastic anisotropy. Using Kachanov's (1992, 1993) formulation we analyzed the effects of an axisymmetric system of microcracks on seismic anisotropy. The elastic behavior of such a cracked rock is transversely isotropic, and its seismic properties can be characterized by the three Thomsen parameters. In this study we calculated the parameters ε, delta and gamma under dry and saturated conditions. We derived analytic expressions for the model proposed by Sayers & Kachanov (1995), which assumes that the contribution from the fourth rank crack density tensor is negligible. This model predicts that the elliptic anisotropy condition ε=delta is obeyed in a dry rock. Guided by microstructural observations we adopted a two-parameter axisymmetric distribution to characterize the crack density, which predicts that delta and gamma in a fluid saturated rock are related to ε in a nonlinear manner. All three Thomsen parameters are sensitively dependent on the crack density difference. While our model shows basic agreement with some of the laboratory data on seismic anisotropy in saturated shale, there are discrepancies which suggest that the petrofabric associated with preferred orientation of clay minerals and elastic anisotropy of the rock matrix may have considerable influence which should not be neglected in model. Preliminary comparison with borehole log data suggests rock physics tests which may be useful for interpreting the shear wave anisotropy observations.
We studied the brittle-ductile transition in three porous carbonates, Indiana, USA, Majella, Ital... more We studied the brittle-ductile transition in three porous carbonates, Indiana, USA, Majella, Italy, and Leitha, Austria, with porosity ranging between 16 and 31%. A series of triaxial experiments were performed at room temperature, constant strain rate, and at effective pressures ranging from 5 to 150 MPa. Several sets of X-ray Tomography images were acquired before and after deformation. 3D digital image correlation (DIC) was performed on the images of the intact and deformed samples. The use of 3D-volumetric DIC allowed us to map out the subtle development of strain localization associated with the transition from brittle faulting to cataclastic flow in the three limestones. Our observations showed that strain localization may develop at relatively small axial strains of ~1%, in both the brittle faulting and transitional regimes. In Majella limestone (porosity = 31%), the localized deformation involved both shear and compaction. Compaction bands were only observed in less cemented samples of Leitha limestone. (Less)
Journal of Geophysical Research: Solid Earth, 2020
HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. Copyright
We analyse a new model to estimate the change in gravity and in elevation caused by volcanic erup... more We analyse a new model to estimate the change in gravity and in elevation caused by volcanic eruption or inflation. In the new model, a permeable, porous zone surrounds a spherical magma chamber. Magma may enter or leave the magma chamber and, independently, the permeable zone. This arrangement simulates the flow processes inferred from field studies, and provides a degree of freedom not available in the classic model proposed by Mogi and used by many others since then. We find, in agreement with field data and previous analyses of the Mogi model, that the change in edifice volume is smaller than the volume of magma which produces it. The local change in gravity is found to be proportional to the local elevation change, the constant of proportionality being positive or negative, depending on whether magma flow is directed into or out of the chamber or infiltrated zone.
The thermal expansion of rocks has customarily been measured at room pressure; it is typically ir... more The thermal expansion of rocks has customarily been measured at room pressure; it is typically irreversible after heating above room temperature and the coefficient of thermal expansion of a rock is usually much larger than the average coefficients for the minerals in the rock. We ...
Microcrack statistical data required for the modelling of thermophysical properties and failure b... more Microcrack statistical data required for the modelling of thermophysical properties and failure behavior of rocks have been obtained by a geometric probability approach and by direct measurement on plane sections. A comparison of the two shows that the former is efficient and provides ...
Thrusting earthquakes in subduction zones generally occur along only part of the plate boundary, ... more Thrusting earthquakes in subduction zones generally occur along only part of the plate boundary, with motion along the shallowest part of the plate boundary occurring aseismically. The maximum size of subduction boundary thrust earthquakes depends strongly upon the down-dip width of the seismogenic zone. The single most uncertain factor in determining that width is the location of the up-dip limit of the zone (the seismic front), which depends upon the mechanical state of the sedimentary rocks in the plate boundary zone. In order to come to a better understanding of the seismic potential of sediments in a subduction zone, we carried out a series of triaxial experiments on Berea and Kayenta sandstones. Based on our experimental data, a brittle-ductile transition map was constructed showing that both porosity and effective pressure are important factors controlling the transition from brittle to macroscopically ductile behavior in porous rocks. In the brittle field, a sample fails by shear localization on one slip plane accompanied by strain softening and dilatancy, whereas in the ductile field, a sample deforms homogeneously with a constant yield stress or slight hardening. By comparing such a map with the estimated porosity profile of an accretionary wedge, the likely nature and rough location of the boundary between brittle and ductile behavior can be inferred. If the sediments along a plate boundary are too young and undercompacted to be capable of brittle shear localization, then their deformation is likely to be aseismic. In this way, it may be possible for even a very broad fore-arcs to produce no great earthquakes. However, great earthquakes are to be expected at margins that have large zones of plate contact along which many sediments are compacted and well lithified. Such rocks are expected to be capable of shear localization and brittle failure with the potential for stick-slip behavior.
Fluid inclusions break, or decrepitate, when the fluid pressure exceeds the least principal litho... more Fluid inclusions break, or decrepitate, when the fluid pressure exceeds the least principal lithostatic stress by a critical amount. After decrepitation, excess fluid pressure is relaxed, resulting in crack arrest; subsequently, crack healing may occur. Existing models of decrepitation do not ...
Journal of Geophysical Research: Solid Earth, 2019
HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
The pore structure in intact and inelastically deformed Indiana limestone have been studied using... more The pore structure in intact and inelastically deformed Indiana limestone have been studied using x-ray microtomography imaging. Guided by detailed microstructural observations and using Multi-level Otsu’s thresholding method, the 3D images acquired at voxel side length of 4 μm were segmented into three domains: solid grains, macropores and an intermediate zone dominated by microporosity. Local Porosity can be defined to infer the porosity of each voxel. The macropores were individually identified by morphological processing and their shape quantified by their sphericity and equivalent diameter. With this segmentation, we obtained statistics on macropores on intact and deformed Indiana limestone which shows that inelastic compaction was followed by a significant reduction in the number of macropores. And also our results revealed the great potentiality to produce a quantitative analysis on porous material with the aid of micro CT images.
The fate and transport of metals and volatile organic compounds at two field sites were observed ... more The fate and transport of metals and volatile organic compounds at two field sites were observed and characterized at the coastline and the hyporheic zone. Metal concentrations were determined at West Neck Bay, both at the coastline and up to 90 ft offshore. Qualitatively, it appears that the groundwater discharging into West Neck Bay is composed of three components. These components result from groundwater originating near the coast, at a landfill approximately 1200 ft upgradient, and from residential areas further inland on Shelter Island. Comparison with an analytical flow net indicates that these observations cannot be explained by advective transport alone, and it is likely that colloidal transport plays a major role in the study area. Naphthalene concentrations entering Lawrence Creek in Bayshore, NY were also determined and a methodology is introduced at that site for determining contaminant or nutrient fluxes into a coastal environment.
Shelter Island draws all of its water from a thin wedge (with an average thickness of ~ 80’) of t... more Shelter Island draws all of its water from a thin wedge (with an average thickness of ~ 80’) of the anisotropic and unconfined Upper Glacial aquifer, that is surrounded on all sides and below by saline groundwater. Consequently, the aquifer is vulnerable to contamination, mainly salt water intrusion that may be aggravated by well pumping near the coast. In order to assess and manage threats to the water supply, such as chemical contamination and salt water intrusion, it is necessary to understand the nature of groundwater flow and its interplay with coastal dynamics in the region. The overall objective of this study is to construct a 3-dimensional, finite-difference model of the groundwater flow for the coastal areas of Shelter Island using the MODFLOW code. The prediction of a numerical model is sensitively dependent on the boundary conditions. For a steady flow model, it is necessary to prescribe the spatial extent and recharge of the contributing area, and the spatial extent of t...
International Journal of Rock Mechanics and Mining Sciences, 2018
In Fontainebleau sandstone, the evolution of transport properties with porosity is related to cha... more In Fontainebleau sandstone, the evolution of transport properties with porosity is related to changes in both the size and connectivity of the pore space. Microcomputed tomography can be used to characterize the relevant geometric attributes, with the resolution that is sufficiently refined for realistic simulation of transport properties based on the 3D image. In this study, we adopted a hybrid computation scheme that is based on a hierarchical multi-scale approach. The specimen was partitioned into cubic sub-volumes for pore-scale simulation of hydraulic permeability and formation factor using the lattice Boltzmann method. The pore-scale results were then linked with finite element simulation in a homogenized scheme to compute and upscale the transport properties to specimen scale. The simulated permeability and formation factor have magnitude and anisotropy that are in good agreement with experimental rock physics data. Together with simulated and measured values of connected porosity and specific surface area, they provide useful insights into how pore geometry controls the evolution of the transport properties.
We present a SE(3)-equivariant graph neural network (GNN) approach that directly predicting the f... more We present a SE(3)-equivariant graph neural network (GNN) approach that directly predicting the formation factor and effective permeability from micro-CT images. FFT solvers are established to compute both the formation factor and effective permeability, while the topology and geometry of the pore space are represented by a persistence-based Morse graph. Together, they constitute the database for training, validating, and testing the neural networks. While the graph and Euclidean convolutional approaches both employ neural networks to generate low-dimensional latent space to represent the features of the micro-structures for forward predictions, the SE(3) equivariant neural network is found to generate more accurate predictions, especially when the training data is limited. Numerical experiments have also shown that the new SE(3) approach leads to predictions that fulfill the material frame indifference whereas the predictions from classical convolutional neural networks (CNN) may suffer from spurious dependence on the coordinate system of the training data. Comparisons among predictions inferred from training the CNN and those from graph convolutional neural networks (GNN) with and without the equivariant constraint indicate that the equivariant graph neural network seems to perform better than the CNN and GNN without enforcing equivariant constraints.
Dilatancy is universally observed as a precursor of brittle faulting in geomaterials. Laboratory ... more Dilatancy is universally observed as a precursor of brittle faulting in geomaterials. Laboratory data on permeability of triaxially compressed rocks indicate that its evolution during deformation can be very complex. In low-porosity crystalline rocks, permeability enhancement is generally observed during dilatancy and a positive correlation exists between permeability and porosity. In porous siliciclastic rocks, experimental data show that the permeability would actually decrease while the pore space dilates as a sample is stressed to brittle failure. With constraints from microstructural observations, percolation network models provide physical insights into the interplay of stress-induced cracking and pre-existing pore structure that induces such negative correlation between porosity and permeability changes. The laboratory data suggest that tectonic deformation in a seismogenic system located in crystalline rock can potentially induce massive fluid discharge along conduits, which may be localized in a high-permeability heterogeneity such as the damage zone. However, it is unlikely that faulting in porous rock formations and shear displacement along gouge zones can provide conduits for fluid along fault zones. To emphasize the fundamental differences between a compact and a porous rock, separate deformation-permeability maps in the stress space are proposed as conceptual models for the permeability evolution. In a region of active faulting, the loading path typically involves variations in the deviatoric stresses, as well as the mean stress and pore pressure. Laboratory data provide important insight into the interplay of deviatoric stresses, mean stress, and pore pressure in relation to permeability evolution and fluid transport. Hydromechanical parameters that control the generation and maintenance of pore pressure excess are also identified.
HAL (Le Centre pour la Communication Scientifique Directe), Jun 25, 2011
HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
Geological Society, London, Special Publications, 2007
Crack and textural fabrics have significant control over the development of mechanical anisotropy... more Crack and textural fabrics have significant control over the development of mechanical anisotropy in a rock. Bedding in sedimentary rocks, cleavage in slates, preferred orientation of anisotropic minerals and anisotropic distribution of microcracks can all contribute to elastic anisotropy. Using Kachanov's (1992, 1993) formulation we analyzed the effects of an axisymmetric system of microcracks on seismic anisotropy. The elastic behavior of such a cracked rock is transversely isotropic, and its seismic properties can be characterized by the three Thomsen parameters. In this study we calculated the parameters ε, delta and gamma under dry and saturated conditions. We derived analytic expressions for the model proposed by Sayers & Kachanov (1995), which assumes that the contribution from the fourth rank crack density tensor is negligible. This model predicts that the elliptic anisotropy condition ε=delta is obeyed in a dry rock. Guided by microstructural observations we adopted a two-parameter axisymmetric distribution to characterize the crack density, which predicts that delta and gamma in a fluid saturated rock are related to ε in a nonlinear manner. All three Thomsen parameters are sensitively dependent on the crack density difference. While our model shows basic agreement with some of the laboratory data on seismic anisotropy in saturated shale, there are discrepancies which suggest that the petrofabric associated with preferred orientation of clay minerals and elastic anisotropy of the rock matrix may have considerable influence which should not be neglected in model. Preliminary comparison with borehole log data suggests rock physics tests which may be useful for interpreting the shear wave anisotropy observations.
We studied the brittle-ductile transition in three porous carbonates, Indiana, USA, Majella, Ital... more We studied the brittle-ductile transition in three porous carbonates, Indiana, USA, Majella, Italy, and Leitha, Austria, with porosity ranging between 16 and 31%. A series of triaxial experiments were performed at room temperature, constant strain rate, and at effective pressures ranging from 5 to 150 MPa. Several sets of X-ray Tomography images were acquired before and after deformation. 3D digital image correlation (DIC) was performed on the images of the intact and deformed samples. The use of 3D-volumetric DIC allowed us to map out the subtle development of strain localization associated with the transition from brittle faulting to cataclastic flow in the three limestones. Our observations showed that strain localization may develop at relatively small axial strains of ~1%, in both the brittle faulting and transitional regimes. In Majella limestone (porosity = 31%), the localized deformation involved both shear and compaction. Compaction bands were only observed in less cemented samples of Leitha limestone. (Less)
Journal of Geophysical Research: Solid Earth, 2020
HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. Copyright
We analyse a new model to estimate the change in gravity and in elevation caused by volcanic erup... more We analyse a new model to estimate the change in gravity and in elevation caused by volcanic eruption or inflation. In the new model, a permeable, porous zone surrounds a spherical magma chamber. Magma may enter or leave the magma chamber and, independently, the permeable zone. This arrangement simulates the flow processes inferred from field studies, and provides a degree of freedom not available in the classic model proposed by Mogi and used by many others since then. We find, in agreement with field data and previous analyses of the Mogi model, that the change in edifice volume is smaller than the volume of magma which produces it. The local change in gravity is found to be proportional to the local elevation change, the constant of proportionality being positive or negative, depending on whether magma flow is directed into or out of the chamber or infiltrated zone.
The thermal expansion of rocks has customarily been measured at room pressure; it is typically ir... more The thermal expansion of rocks has customarily been measured at room pressure; it is typically irreversible after heating above room temperature and the coefficient of thermal expansion of a rock is usually much larger than the average coefficients for the minerals in the rock. We ...
Microcrack statistical data required for the modelling of thermophysical properties and failure b... more Microcrack statistical data required for the modelling of thermophysical properties and failure behavior of rocks have been obtained by a geometric probability approach and by direct measurement on plane sections. A comparison of the two shows that the former is efficient and provides ...
Thrusting earthquakes in subduction zones generally occur along only part of the plate boundary, ... more Thrusting earthquakes in subduction zones generally occur along only part of the plate boundary, with motion along the shallowest part of the plate boundary occurring aseismically. The maximum size of subduction boundary thrust earthquakes depends strongly upon the down-dip width of the seismogenic zone. The single most uncertain factor in determining that width is the location of the up-dip limit of the zone (the seismic front), which depends upon the mechanical state of the sedimentary rocks in the plate boundary zone. In order to come to a better understanding of the seismic potential of sediments in a subduction zone, we carried out a series of triaxial experiments on Berea and Kayenta sandstones. Based on our experimental data, a brittle-ductile transition map was constructed showing that both porosity and effective pressure are important factors controlling the transition from brittle to macroscopically ductile behavior in porous rocks. In the brittle field, a sample fails by shear localization on one slip plane accompanied by strain softening and dilatancy, whereas in the ductile field, a sample deforms homogeneously with a constant yield stress or slight hardening. By comparing such a map with the estimated porosity profile of an accretionary wedge, the likely nature and rough location of the boundary between brittle and ductile behavior can be inferred. If the sediments along a plate boundary are too young and undercompacted to be capable of brittle shear localization, then their deformation is likely to be aseismic. In this way, it may be possible for even a very broad fore-arcs to produce no great earthquakes. However, great earthquakes are to be expected at margins that have large zones of plate contact along which many sediments are compacted and well lithified. Such rocks are expected to be capable of shear localization and brittle failure with the potential for stick-slip behavior.
Fluid inclusions break, or decrepitate, when the fluid pressure exceeds the least principal litho... more Fluid inclusions break, or decrepitate, when the fluid pressure exceeds the least principal lithostatic stress by a critical amount. After decrepitation, excess fluid pressure is relaxed, resulting in crack arrest; subsequently, crack healing may occur. Existing models of decrepitation do not ...
Journal of Geophysical Research: Solid Earth, 2019
HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
The pore structure in intact and inelastically deformed Indiana limestone have been studied using... more The pore structure in intact and inelastically deformed Indiana limestone have been studied using x-ray microtomography imaging. Guided by detailed microstructural observations and using Multi-level Otsu’s thresholding method, the 3D images acquired at voxel side length of 4 μm were segmented into three domains: solid grains, macropores and an intermediate zone dominated by microporosity. Local Porosity can be defined to infer the porosity of each voxel. The macropores were individually identified by morphological processing and their shape quantified by their sphericity and equivalent diameter. With this segmentation, we obtained statistics on macropores on intact and deformed Indiana limestone which shows that inelastic compaction was followed by a significant reduction in the number of macropores. And also our results revealed the great potentiality to produce a quantitative analysis on porous material with the aid of micro CT images.
Uploads
Papers by TENG-FONG WONG