Aly Abdelaziz - Academia.edu (original) (raw)

Papers by Aly Abdelaziz

Research paper thumbnail of Stability analysis of reservoir slopes under fluctuating water levels using the combined finite-discrete element method

Acta Geotechnica, Apr 18, 2023

Research paper thumbnail of The role of discontinuities in rock slope stability: Insights from a combined finite-discrete element simulation

Computers and Geotechnics, Jul 1, 2022

Research paper thumbnail of Simulating the entire progressive failure process of rock slopes using the combined finite-discrete element method

Computers and Geotechnics, 2022

Research paper thumbnail of Grain based modelling of rocks using the combined finite-discrete element method

Computers and Geotechnics, Nov 1, 2018

This paper describes the implementation and advantages of grain based modelling (GBM) in the comb... more This paper describes the implementation and advantages of grain based modelling (GBM) in the combined finitediscrete element method (FDEM) to study the mechanical behaviour of crystalline rocks. GBM in FDEM honours grain petrological properties and explicitly models grain boundaries. The simulation results demonstrated that GBM in FDEM predicted more realistic microscopic and macroscopic response of rocks than conventional FDEM models. The explicit modelling of crack boundaries captured microscopic failure transition from along grain boundaries to coalescence along the shear band, dominated by intraphase cracks. This novel framework presents a gateway into further understanding the behaviour of crystalline rocks and granular minerals.

Research paper thumbnail of Modelling Failure in Layered Geological Formations - FDEM: A Micro-mechanical Approach that Bridges Across Scales

Research paper thumbnail of Investigating Frictional Behavior of Micro-Cracks Using Grain Based Modelling in the Combined Finite-Discrete Element Method (FDEM)

52nd U.S. Rock Mechanics/Geomechanics Symposium, Jun 17, 2018

Research paper thumbnail of Example framework for evaluation of synthetic rock-like materials as applied to a commercial gypsum cement

International Journal of Rock Mechanics and Mining Sciences, Sep 1, 2023

Research paper thumbnail of Numerical Investigation of the Influence of Bedding Plane Thickness and Friction on Cracking Pattern and Mechanical Behavior of Shale Under Unconfined Loading Condition Using the Finite-Discrete Element Method (FDEM)

All Days, Jun 26, 2022

ABSTRACT: The finely bedded structure of shale makes its mechanical behavior highly anisotropic b... more ABSTRACT: The finely bedded structure of shale makes its mechanical behavior highly anisotropic both in terms of deformation and strength. The variations in the bedding plane thickness originates from different sedimentation processes occurred during the formation of the shale. It is well known that these features act as weakness planes in the rock matrix and thus studying the mechanical behavior of shale should incorporate the influence of bedding planes. Numerous investigations have been conducted so far to understand the influence of bedding plane orientation on the deformation and strength of shale. However, there exist only a few investigations which studied the influence that bedding plane thickness and friction might have on the mechanical response and cracking pattern of the rock. The present study discusses the results of a series of unconfined compressive test simulations conducted on shale samples with different bedding plane thickness and friction values using the combined Finite-Discrete Element Method (FDEM). The bedding planes have been discretely modeled as a distribution of preferentially oriented defects inside the rock matrix. Experimental results from the shaly facies of the Opalinus Clay at the Mont Terri Underground Research Laboratory (URL) have been used as input parameters to calibrate the numerical model. Simulation results show a difference in cracking pattern and strength of the rock owing to different bedding plane thicknesses but almost no effect due to different bedding plane frictions. 1. INTRODUCTION Shale formations play an integral role in many civil, petroleum, and environmental engineering projects. Shales not only act as an unconventional reservoir for extracting hydrocarbon resources, but also as a potential host rock for underground geological storage of nuclear wastes and as caprock for Carbon Capture and Sequestration (CCS) operations. Shale is formed through the sedimentation and subsequent hardening of fine sediments and thus it features a finely laminated and bedded structure. Platy particles tend to deposit in distinct orientations during the sedimentation of the shale causing an anisotropic texture at the macroscopic scale (Wenk et al., 2008). The layered structure of the shale makes its deformation and strength characteristics highly anisotropic at different scales, for example, at a larger scale it is attributed to the presence of bedding planes (Saroglou and Tsiambaos, 2008). The temporal variations in the sediment supply and flow velocity causes the thickness and properties of the bedding planes to differ along the deposition axis (O’Brien, 1996). These bedding planes act as weakness planes inside the rock matrix and thus understanding the shale mechanical behavior should incorporate the influence of bedding planes (Woo et al., 2021). In addition, the existence of physical discontinuities in the rock such as natural fractures or tectonic features contributes to the anisotropy at the rock mass scale.

Research paper thumbnail of Understanding progressive rock failure using ultrasonic tomography and numerical simulation

Research paper thumbnail of Novel Mechanical Classification Method of Rock Based on the Uniaxial Compressive Strength and Brazilian Disc Strength

Rock Mechanics and Rock Engineering, Jan 25, 2022

• Graphical classification based on the UCS:BDS ratio. • Practical tool to estimate the strength ... more • Graphical classification based on the UCS:BDS ratio. • Practical tool to estimate the strength ratio of rock in a variety of engineering construction projects. • Estimating material properties in the pre-feasibility stages of projects. • Database of over 500 pairs of UCS and BDS values.

Research paper thumbnail of Mechanical Characterization, Anisotropy, and Failure Pattern of Unconventional Reservoirs for Wellbore Stability and Fracture Enhancement

Proceedings of the 11th Unconventional Resources Technology Conference

Research paper thumbnail of Rock Fabric Not Principal Stress Dictates SRV: The Story of How a ~70 Year Old Discounted Data Point Still Plagues Our Industry and How True Triaxial Testing Finally Confirms It

Proceedings of the 11th Unconventional Resources Technology Conference

Research paper thumbnail of Numerical investigation of progressive damage and the effect of layup in overheight compact tension tests

Composites Part A: Applied Science and Manufacturing, 2012

This paper presents results from a new approach to finite element modelling of notched damage in ... more This paper presents results from a new approach to finite element modelling of notched damage in composite materials using interface elements to model intra-and inter-ply damage. The technique is used to examine and predict the failures observed in tensile, double edge notched specimens using four different layups made up from glass/epoxy prepreg. Due to the detailed modelling of the individual damage modes their interaction is well characterised. The analytical results obtained compare well with detailed test observations, capturing delamination and intra-ply splitting. By including the sub-critical damage that occurs at the notch tip in the model, the stress singularity is removed and failure criteria can be used to predict ultimate ply failures.

Research paper thumbnail of Integrating Deep Learning and High-Resolution Imaging to Characterize Shale Fracture Network Generated by Laboratory True-Triaxial Hydraulic Fracturing

Social Science Research Network, 2023

Research paper thumbnail of Numerical investigation of progressive damage and associated seismicity on a laboratory fault

arXiv (Cornell University), Jan 10, 2023

Understanding rock shear failure behavior is crucial to gain insights into slip-related geohazard... more Understanding rock shear failure behavior is crucial to gain insights into slip-related geohazards such as rock avalanches, landslides, and earthquakes. However, descriptions of the progressive damage on the shear surface are still incomplete or ambiguous. In this study, we use the hybrid finite-discrete element method (FDEM) to simulate a shear experiment and obtain a detailed comprehension of shear induced progressive damage and the associated seismic activity. We built a laboratory fault model from high resolution surface scans and micro-CT imaging. Our results show that under quasi-static shear loading, the fault surface experiences local dynamic seismic activities. We found that the seismic activity is related to the stress concentration on interlocking asperities. This interlocking behavior (i) causes stress concentration at the region of contact that could reach the compressive strength, and (ii) produces tensile stress up to the tensile strength in the region adjacent to the contact area. Thus, different failure mechanisms and damage patterns including crushing and sub-vertical fracturing are observed on the rough surface. Asperity failure creates rapid local slips resulting in significant stress perturbations that alter the overall stress condition and may trigger the slip of adjacent critically stressed asperities. We found that the 2 spatial distribution of the damaged asperities and the seismic activity is highly heterogeneous; regions with intense asperity interactions formed gouge material, while others exhibit minimal to no damage. These results emphasize the important role of surface roughness in controlling the overall shear behavior and the local dynamic seismic activities on faults.

Research paper thumbnail of Stability analysis of reservoir slopes under fluctuating water levels using the combined finite-discrete element method

Research paper thumbnail of Example framework for evaluation of synthetic rock-like materials as applied to a commercial gypsum cement

International Journal of Rock Mechanics and Mining Sciences

Research paper thumbnail of Fracture Network in a Shale Cube Hydraulically Fractured in the Laboratory

Research paper thumbnail of Integrating Deep Learning and High-Resolution Imaging to Characterize Shale Fracture Network Generated by Laboratory True-Triaxial Hydraulic Fracturing

Research paper thumbnail of Numerical Investigation of the Influence of Bedding Plane Thickness and Friction on Cracking Pattern and Mechanical Behavior of Shale Under Unconfined Loading Condition Using the Finite-Discrete Element Method (FDEM)

All Days

ABSTRACT: The finely bedded structure of shale makes its mechanical behavior highly anisotropic b... more ABSTRACT: The finely bedded structure of shale makes its mechanical behavior highly anisotropic both in terms of deformation and strength. The variations in the bedding plane thickness originates from different sedimentation processes occurred during the formation of the shale. It is well known that these features act as weakness planes in the rock matrix and thus studying the mechanical behavior of shale should incorporate the influence of bedding planes. Numerous investigations have been conducted so far to understand the influence of bedding plane orientation on the deformation and strength of shale. However, there exist only a few investigations which studied the influence that bedding plane thickness and friction might have on the mechanical response and cracking pattern of the rock. The present study discusses the results of a series of unconfined compressive test simulations conducted on shale samples with different bedding plane thickness and friction values using the combin...

Research paper thumbnail of Stability analysis of reservoir slopes under fluctuating water levels using the combined finite-discrete element method

Acta Geotechnica, Apr 18, 2023

Research paper thumbnail of The role of discontinuities in rock slope stability: Insights from a combined finite-discrete element simulation

Computers and Geotechnics, Jul 1, 2022

Research paper thumbnail of Simulating the entire progressive failure process of rock slopes using the combined finite-discrete element method

Computers and Geotechnics, 2022

Research paper thumbnail of Grain based modelling of rocks using the combined finite-discrete element method

Computers and Geotechnics, Nov 1, 2018

This paper describes the implementation and advantages of grain based modelling (GBM) in the comb... more This paper describes the implementation and advantages of grain based modelling (GBM) in the combined finitediscrete element method (FDEM) to study the mechanical behaviour of crystalline rocks. GBM in FDEM honours grain petrological properties and explicitly models grain boundaries. The simulation results demonstrated that GBM in FDEM predicted more realistic microscopic and macroscopic response of rocks than conventional FDEM models. The explicit modelling of crack boundaries captured microscopic failure transition from along grain boundaries to coalescence along the shear band, dominated by intraphase cracks. This novel framework presents a gateway into further understanding the behaviour of crystalline rocks and granular minerals.

Research paper thumbnail of Modelling Failure in Layered Geological Formations - FDEM: A Micro-mechanical Approach that Bridges Across Scales

Research paper thumbnail of Investigating Frictional Behavior of Micro-Cracks Using Grain Based Modelling in the Combined Finite-Discrete Element Method (FDEM)

52nd U.S. Rock Mechanics/Geomechanics Symposium, Jun 17, 2018

Research paper thumbnail of Example framework for evaluation of synthetic rock-like materials as applied to a commercial gypsum cement

International Journal of Rock Mechanics and Mining Sciences, Sep 1, 2023

Research paper thumbnail of Numerical Investigation of the Influence of Bedding Plane Thickness and Friction on Cracking Pattern and Mechanical Behavior of Shale Under Unconfined Loading Condition Using the Finite-Discrete Element Method (FDEM)

All Days, Jun 26, 2022

ABSTRACT: The finely bedded structure of shale makes its mechanical behavior highly anisotropic b... more ABSTRACT: The finely bedded structure of shale makes its mechanical behavior highly anisotropic both in terms of deformation and strength. The variations in the bedding plane thickness originates from different sedimentation processes occurred during the formation of the shale. It is well known that these features act as weakness planes in the rock matrix and thus studying the mechanical behavior of shale should incorporate the influence of bedding planes. Numerous investigations have been conducted so far to understand the influence of bedding plane orientation on the deformation and strength of shale. However, there exist only a few investigations which studied the influence that bedding plane thickness and friction might have on the mechanical response and cracking pattern of the rock. The present study discusses the results of a series of unconfined compressive test simulations conducted on shale samples with different bedding plane thickness and friction values using the combined Finite-Discrete Element Method (FDEM). The bedding planes have been discretely modeled as a distribution of preferentially oriented defects inside the rock matrix. Experimental results from the shaly facies of the Opalinus Clay at the Mont Terri Underground Research Laboratory (URL) have been used as input parameters to calibrate the numerical model. Simulation results show a difference in cracking pattern and strength of the rock owing to different bedding plane thicknesses but almost no effect due to different bedding plane frictions. 1. INTRODUCTION Shale formations play an integral role in many civil, petroleum, and environmental engineering projects. Shales not only act as an unconventional reservoir for extracting hydrocarbon resources, but also as a potential host rock for underground geological storage of nuclear wastes and as caprock for Carbon Capture and Sequestration (CCS) operations. Shale is formed through the sedimentation and subsequent hardening of fine sediments and thus it features a finely laminated and bedded structure. Platy particles tend to deposit in distinct orientations during the sedimentation of the shale causing an anisotropic texture at the macroscopic scale (Wenk et al., 2008). The layered structure of the shale makes its deformation and strength characteristics highly anisotropic at different scales, for example, at a larger scale it is attributed to the presence of bedding planes (Saroglou and Tsiambaos, 2008). The temporal variations in the sediment supply and flow velocity causes the thickness and properties of the bedding planes to differ along the deposition axis (O’Brien, 1996). These bedding planes act as weakness planes inside the rock matrix and thus understanding the shale mechanical behavior should incorporate the influence of bedding planes (Woo et al., 2021). In addition, the existence of physical discontinuities in the rock such as natural fractures or tectonic features contributes to the anisotropy at the rock mass scale.

Research paper thumbnail of Understanding progressive rock failure using ultrasonic tomography and numerical simulation

Research paper thumbnail of Novel Mechanical Classification Method of Rock Based on the Uniaxial Compressive Strength and Brazilian Disc Strength

Rock Mechanics and Rock Engineering, Jan 25, 2022

• Graphical classification based on the UCS:BDS ratio. • Practical tool to estimate the strength ... more • Graphical classification based on the UCS:BDS ratio. • Practical tool to estimate the strength ratio of rock in a variety of engineering construction projects. • Estimating material properties in the pre-feasibility stages of projects. • Database of over 500 pairs of UCS and BDS values.

Research paper thumbnail of Mechanical Characterization, Anisotropy, and Failure Pattern of Unconventional Reservoirs for Wellbore Stability and Fracture Enhancement

Proceedings of the 11th Unconventional Resources Technology Conference

Research paper thumbnail of Rock Fabric Not Principal Stress Dictates SRV: The Story of How a ~70 Year Old Discounted Data Point Still Plagues Our Industry and How True Triaxial Testing Finally Confirms It

Proceedings of the 11th Unconventional Resources Technology Conference

Research paper thumbnail of Numerical investigation of progressive damage and the effect of layup in overheight compact tension tests

Composites Part A: Applied Science and Manufacturing, 2012

This paper presents results from a new approach to finite element modelling of notched damage in ... more This paper presents results from a new approach to finite element modelling of notched damage in composite materials using interface elements to model intra-and inter-ply damage. The technique is used to examine and predict the failures observed in tensile, double edge notched specimens using four different layups made up from glass/epoxy prepreg. Due to the detailed modelling of the individual damage modes their interaction is well characterised. The analytical results obtained compare well with detailed test observations, capturing delamination and intra-ply splitting. By including the sub-critical damage that occurs at the notch tip in the model, the stress singularity is removed and failure criteria can be used to predict ultimate ply failures.

Research paper thumbnail of Integrating Deep Learning and High-Resolution Imaging to Characterize Shale Fracture Network Generated by Laboratory True-Triaxial Hydraulic Fracturing

Social Science Research Network, 2023

Research paper thumbnail of Numerical investigation of progressive damage and associated seismicity on a laboratory fault

arXiv (Cornell University), Jan 10, 2023

Understanding rock shear failure behavior is crucial to gain insights into slip-related geohazard... more Understanding rock shear failure behavior is crucial to gain insights into slip-related geohazards such as rock avalanches, landslides, and earthquakes. However, descriptions of the progressive damage on the shear surface are still incomplete or ambiguous. In this study, we use the hybrid finite-discrete element method (FDEM) to simulate a shear experiment and obtain a detailed comprehension of shear induced progressive damage and the associated seismic activity. We built a laboratory fault model from high resolution surface scans and micro-CT imaging. Our results show that under quasi-static shear loading, the fault surface experiences local dynamic seismic activities. We found that the seismic activity is related to the stress concentration on interlocking asperities. This interlocking behavior (i) causes stress concentration at the region of contact that could reach the compressive strength, and (ii) produces tensile stress up to the tensile strength in the region adjacent to the contact area. Thus, different failure mechanisms and damage patterns including crushing and sub-vertical fracturing are observed on the rough surface. Asperity failure creates rapid local slips resulting in significant stress perturbations that alter the overall stress condition and may trigger the slip of adjacent critically stressed asperities. We found that the 2 spatial distribution of the damaged asperities and the seismic activity is highly heterogeneous; regions with intense asperity interactions formed gouge material, while others exhibit minimal to no damage. These results emphasize the important role of surface roughness in controlling the overall shear behavior and the local dynamic seismic activities on faults.

Research paper thumbnail of Stability analysis of reservoir slopes under fluctuating water levels using the combined finite-discrete element method

Research paper thumbnail of Example framework for evaluation of synthetic rock-like materials as applied to a commercial gypsum cement

International Journal of Rock Mechanics and Mining Sciences

Research paper thumbnail of Fracture Network in a Shale Cube Hydraulically Fractured in the Laboratory

Research paper thumbnail of Integrating Deep Learning and High-Resolution Imaging to Characterize Shale Fracture Network Generated by Laboratory True-Triaxial Hydraulic Fracturing

Research paper thumbnail of Numerical Investigation of the Influence of Bedding Plane Thickness and Friction on Cracking Pattern and Mechanical Behavior of Shale Under Unconfined Loading Condition Using the Finite-Discrete Element Method (FDEM)

All Days

ABSTRACT: The finely bedded structure of shale makes its mechanical behavior highly anisotropic b... more ABSTRACT: The finely bedded structure of shale makes its mechanical behavior highly anisotropic both in terms of deformation and strength. The variations in the bedding plane thickness originates from different sedimentation processes occurred during the formation of the shale. It is well known that these features act as weakness planes in the rock matrix and thus studying the mechanical behavior of shale should incorporate the influence of bedding planes. Numerous investigations have been conducted so far to understand the influence of bedding plane orientation on the deformation and strength of shale. However, there exist only a few investigations which studied the influence that bedding plane thickness and friction might have on the mechanical response and cracking pattern of the rock. The present study discusses the results of a series of unconfined compressive test simulations conducted on shale samples with different bedding plane thickness and friction values using the combin...