R. Choens, Kristopher L. Kuhlman, C. Herrick, Shawn Otto
A series of field-based multi-physics observations were conducted as part of the Brine Availability Test in Salt (BATS) underground at the Waste Isolation Pilot Plant (WIPP), near Carlsbad, NM. Observations were made of brine production, temperature, electrical resistivity, acoustic emissions (AE), and gas/liquid tracer migration through salt around twin heated/unheated borehole arrays. Here, we present AE results from thermal cycling experiments performed May – July 2021, during which the heater was pulsed several times followed by two longer heated periods. Sixteen AE sensors were installed in three parallel observational boreholes surrounding the central heated borehole. Observed AE demonstrate that heating and cooling cycles significantly impact salt behavior. AE rates increased during heating and increased further upon cooling. Average energy and frequency bandwidth also increased during heating and cooling of salt. Similar behavior was observed for each heating/cooling cycle, suggesting that temperature-enhanced salt healing may have eliminated any threshold loading associated with the onset of AE (i.e., the Kaiser effect). Locations of AE events remained centralized around the borehole. These results show that AE provide valuable information about the thermal behavior of salt, particularly that cooling of salt results in the highest AE behavior.
{"title":"Acoustic Emission Monitoring of Thermal Cycling in Salt at the Waste Isolation Pilot Plant","authors":"R. Choens, Kristopher L. Kuhlman, C. Herrick, Shawn Otto","doi":"10.56952/arma-2022-0296","DOIUrl":"https://doi.org/10.56952/arma-2022-0296","url":null,"abstract":"A series of field-based multi-physics observations were conducted as part of the Brine Availability Test in Salt (BATS) underground at the Waste Isolation Pilot Plant (WIPP), near Carlsbad, NM. Observations were made of brine production, temperature, electrical resistivity, acoustic emissions (AE), and gas/liquid tracer migration through salt around twin heated/unheated borehole arrays. Here, we present AE results from thermal cycling experiments performed May – July 2021, during which the heater was pulsed several times followed by two longer heated periods. Sixteen AE sensors were installed in three parallel observational boreholes surrounding the central heated borehole. Observed AE demonstrate that heating and cooling cycles significantly impact salt behavior. AE rates increased during heating and increased further upon cooling. Average energy and frequency bandwidth also increased during heating and cooling of salt. Similar behavior was observed for each heating/cooling cycle, suggesting that temperature-enhanced salt healing may have eliminated any threshold loading associated with the onset of AE (i.e., the Kaiser effect). Locations of AE events remained centralized around the borehole. These results show that AE provide valuable information about the thermal behavior of salt, particularly that cooling of salt results in the highest AE behavior.","PeriodicalId":418045,"journal":{"name":"Proceedings 56th US Rock Mechanics / Geomechanics Symposium","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114946203","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
W. Kibikas, Stephen Bauer, R. Choens, E. Shalev, V. Lyakhovsky
The Ghareb Formation in the Yasmin Plain of Israel is under investigation as a potential disposal rock for nuclear waste disposal. Triaxial deformation tests and hydrostatic water-permeability tests were conducted with samples of the Ghareb to assess relevant thermal, hydrological, and mechanical properties. Axial deformation tests were performed on dry and water-saturated samples at effective pressures ranging from 0.7 to 19.6 MPa and temperatures of 23 ˚C and 100 ˚C, while permeability tests were conducted at ambient temperatures and effective pressures ranging from 0.7 to 20 MPa. Strength and elastic moduli increase with increasing effective pressure for the triaxial tests. Dry room temperature tests are generally the strongest, while the samples deformed at 100 ˚C exhibit large permanent compaction even at low effective pressures. Water permeability decreases by 1-2 orders of magnitude under hydrostatic conditions while experiencing permanent volume loss of 4-5%. Permeability loss is retained after unloading, resulting from permanent compaction. A 3-D compaction model was used to demonstrate that compaction in one direction is associated with de-compaction in the orthogonal directions. The model accurately reproduces the measured axial and transverse strain components. The experimentally constrained deformational properties of the Ghareb will be used for 3-D thermal-hydrological-mechanical modelling of borehole stability.
{"title":"Thermal-Hydrological-Mechanical Characterization of the Ghareb Formation at Conditions of High-Level Nuclear Waste Disposal","authors":"W. Kibikas, Stephen Bauer, R. Choens, E. Shalev, V. Lyakhovsky","doi":"10.56952/arma-2022-0291","DOIUrl":"https://doi.org/10.56952/arma-2022-0291","url":null,"abstract":"The Ghareb Formation in the Yasmin Plain of Israel is under investigation as a potential disposal rock for nuclear waste disposal. Triaxial deformation tests and hydrostatic water-permeability tests were conducted with samples of the Ghareb to assess relevant thermal, hydrological, and mechanical properties. Axial deformation tests were performed on dry and water-saturated samples at effective pressures ranging from 0.7 to 19.6 MPa and temperatures of 23 ˚C and 100 ˚C, while permeability tests were conducted at ambient temperatures and effective pressures ranging from 0.7 to 20 MPa. Strength and elastic moduli increase with increasing effective pressure for the triaxial tests. Dry room temperature tests are generally the strongest, while the samples deformed at 100 ˚C exhibit large permanent compaction even at low effective pressures. Water permeability decreases by 1-2 orders of magnitude under hydrostatic conditions while experiencing permanent volume loss of 4-5%. Permeability loss is retained after unloading, resulting from permanent compaction. A 3-D compaction model was used to demonstrate that compaction in one direction is associated with de-compaction in the orthogonal directions. The model accurately reproduces the measured axial and transverse strain components. The experimentally constrained deformational properties of the Ghareb will be used for 3-D thermal-hydrological-mechanical modelling of borehole stability.","PeriodicalId":418045,"journal":{"name":"Proceedings 56th US Rock Mechanics / Geomechanics Symposium","volume":"107 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116454332","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Rock salt is being considered as a medium for energy storage and radioactive waste disposal. A Disturbed Rock Zone (DRZ) develops in the immediate vicinity of excavations in rock salt, with an increase in permeability, which alters the migration of gases and liquids around the excavation. When creep occurs adjacent to a stiff inclusion such as a concrete plug, it is expected that the stress state near the inclusion will become more hydrostatic and less deviatoric, promoting healing (permeability reduction) of the DRZ. In this study, we measured the permeability of DRZ rock salt with time adjacent to inclusions (plugs) of varying stiffness to determine how the healing of rock salt, as reflected in the permeability changes, is a function of stress and time. Samples were created with three different inclusion materials in a central hole along the axis of a salt core: (i) very soft silicone sealant, (ii) sorel cement, and (iii) carbon steel. The measured permeabilities are corrected for the gas slippage effect. We observed that the permeability change is a function of the inclusion material. The stiffer the inclusion, the more rapidly the permeability reduces with time.
{"title":"Permeability changes of damaged rock salt adjacent to inclusions of different stiffness","authors":"Ishtiaque Anwar, M. Mills, E. Matteo, J. Stormont","doi":"10.56952/arma-2022-0449","DOIUrl":"https://doi.org/10.56952/arma-2022-0449","url":null,"abstract":"Rock salt is being considered as a medium for energy storage and radioactive waste disposal. A Disturbed Rock Zone (DRZ) develops in the immediate vicinity of excavations in rock salt, with an increase in permeability, which alters the migration of gases and liquids around the excavation. When creep occurs adjacent to a stiff inclusion such as a concrete plug, it is expected that the stress state near the inclusion will become more hydrostatic and less deviatoric, promoting healing (permeability reduction) of the DRZ. In this study, we measured the permeability of DRZ rock salt with time adjacent to inclusions (plugs) of varying stiffness to determine how the healing of rock salt, as reflected in the permeability changes, is a function of stress and time. Samples were created with three different inclusion materials in a central hole along the axis of a salt core: (i) very soft silicone sealant, (ii) sorel cement, and (iii) carbon steel. The measured permeabilities are corrected for the gas slippage effect. We observed that the permeability change is a function of the inclusion material. The stiffer the inclusion, the more rapidly the permeability reduces with time.","PeriodicalId":418045,"journal":{"name":"Proceedings 56th US Rock Mechanics / Geomechanics Symposium","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120839805","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We propose the use of balanced iterative reducing and clustering using hierarchies (BIRCH) combined with linear regression to predict the reduced Young's modulus and hardness of highly heterogeneous materials from a set of nanoindentation experiments. We first use BIRCH to cluster the dataset according to its mineral compositions, which are derived from the spectral matching of energy-dispersive spectroscopy data through the modular automated processing system (MAPS) platform. We observe that grouping our dataset into five clusters yields the best accuracy as well as a reasonable representation of mineralogy in each cluster. Subsequently, we test four types of regression models, namely linear regression, support vector regression, Gaussian process regression, and extreme gradient boosting regression. The linear regression and Gaussian process regression provide the most accurate prediction, and the proposed framework yields R^2 = 0.93 for the test set. Although the study is needed more comprehensively, our results shows that machine learning methods such as linear regression or Gaussian process regression can be used to accurately estimate mechanical properties with a proper number of grouping based on compositional data.
{"title":"Estimation of Mechanical Properties of Mancos Shale using Machine Learning Methods","authors":"H. Yoon, T. Kadeethum","doi":"10.56952/arma-2022-0487","DOIUrl":"https://doi.org/10.56952/arma-2022-0487","url":null,"abstract":"We propose the use of balanced iterative reducing and clustering using hierarchies (BIRCH) combined with linear regression to predict the reduced Young's modulus and hardness of highly heterogeneous materials from a set of nanoindentation experiments. We first use BIRCH to cluster the dataset according to its mineral compositions, which are derived from the spectral matching of energy-dispersive spectroscopy data through the modular automated processing system (MAPS) platform. We observe that grouping our dataset into five clusters yields the best accuracy as well as a reasonable representation of mineralogy in each cluster. Subsequently, we test four types of regression models, namely linear regression, support vector regression, Gaussian process regression, and extreme gradient boosting regression. The linear regression and Gaussian process regression provide the most accurate prediction, and the proposed framework yields R^2 = 0.93 for the test set. Although the study is needed more comprehensively, our results shows that machine learning methods such as linear regression or Gaussian process regression can be used to accurately estimate mechanical properties with a proper number of grouping based on compositional data.","PeriodicalId":418045,"journal":{"name":"Proceedings 56th US Rock Mechanics / Geomechanics Symposium","volume":"83 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133667946","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
E. Robey, J. Pope, O. Vorobiev, S. Torres, M. Hargather, J. Kimberley, Dillon Mann
ABSTRACT: Stimulation of lab scale boreholes was studied using small explosives for improving the development of fracture networks in engineered rock surrogates. The experimental series examines the confluence of initial stress states, orientation of induced discontinuities and their interaction with source generated fracture growth. Density and stress response to the energetic was measured using high-speed schlieren imaging through the transparent polymethyl methacrylate (PMMA) sample. Outer surfaces were instrumented with an acoustic emissions (AE) array to detect 3D location of fracture evolution between wellbores. Prior to testing, the experiments were simulated to predict the generation of a shock induced fracture network between single and multiple wellbores in a variety of stress states. The quantification of wave arrivals, fracture growth, and development of the fracture network in transparent PMMA material is used as further validation against computational models. Understanding the conditions under which fractures propagate in the multivariate environment with small energetics results in improved modeling capability of larger scale wellbores and sources. The present work is part of a broader effort to accurize computational models necessary to predict formation interconnectivity established with energetics in low permeability reservoirs typical of enhanced geothermal systems (EGS).
{"title":"Fracture Detection of Lab Scale Energetic Stimulation","authors":"E. Robey, J. Pope, O. Vorobiev, S. Torres, M. Hargather, J. Kimberley, Dillon Mann","doi":"10.56952/arma-2022-0726","DOIUrl":"https://doi.org/10.56952/arma-2022-0726","url":null,"abstract":"ABSTRACT: Stimulation of lab scale boreholes was studied using small explosives for improving the development of fracture networks in engineered rock surrogates. The experimental series examines the confluence of initial stress states, orientation of induced discontinuities and their interaction with source generated fracture growth. Density and stress response to the energetic was measured using high-speed schlieren imaging through the transparent polymethyl methacrylate (PMMA) sample. Outer surfaces were instrumented with an acoustic emissions (AE) array to detect 3D location of fracture evolution between wellbores. Prior to testing, the experiments were simulated to predict the generation of a shock induced fracture network between single and multiple wellbores in a variety of stress states. The quantification of wave arrivals, fracture growth, and development of the fracture network in transparent PMMA material is used as further validation against computational models. Understanding the conditions under which fractures propagate in the multivariate environment with small energetics results in improved modeling capability of larger scale wellbores and sources. The present work is part of a broader effort to accurize computational models necessary to predict formation interconnectivity established with energetics in low permeability reservoirs typical of enhanced geothermal systems (EGS).","PeriodicalId":418045,"journal":{"name":"Proceedings 56th US Rock Mechanics / Geomechanics Symposium","volume":"234 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122624241","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Hydraulic fracture simulation is a viable tool for optimizing treatments in the field. Current large scale developments create a need for more efficient modeling approaches, which are capable of simulating pad-scale projects. One way to boost computational efficiency of a hydraulic fracturing simulator is to use a coarser mesh. This, however, can noticeably affect accuracy. Traditionally, hydraulic fracturing simulators incrementally propagate fracture by adding one element at a time or by breaking a bond to effectively create a fracture element. The former is the case for displacement discontinuity based methods, while the latter corresponds to finite element and discrete element methods. In this situation, the fracture geometry is inherently quantified within the error bound of a single element size. Alternatively, to reduce this error, one may employ a front tracking algorithm, in which the fracture position varies continuously as a function of the fill of the element. To better understand potential benefits, the purpose of this study is to evaluate accuracy of two hydraulic fracture front algorithms, namely the one with Multi Layer Tip Elements (MuLTipEl) and Implicit Level Set Algorithm (ILSA). Both of these algorithms use the tip asymptotic solution to advance the fracture front, but use very different logic underneath. A series of benchmarking numerical examples with various meshes and the degree of complexity is performed to reveal advantages and limitations of these approaches.
{"title":"A comparison of hydraulic fracture front tracking algorithms","authors":"E. Dontsov, C. Hewson, M. McClure","doi":"10.56952/arma-2022-0114","DOIUrl":"https://doi.org/10.56952/arma-2022-0114","url":null,"abstract":"Hydraulic fracture simulation is a viable tool for optimizing treatments in the field. Current large scale developments create a need for more efficient modeling approaches, which are capable of simulating pad-scale projects. One way to boost computational efficiency of a hydraulic fracturing simulator is to use a coarser mesh. This, however, can noticeably affect accuracy. Traditionally, hydraulic fracturing simulators incrementally propagate fracture by adding one element at a time or by breaking a bond to effectively create a fracture element. The former is the case for displacement discontinuity based methods, while the latter corresponds to finite element and discrete element methods. In this situation, the fracture geometry is inherently quantified within the error bound of a single element size. Alternatively, to reduce this error, one may employ a front tracking algorithm, in which the fracture position varies continuously as a function of the fill of the element. To better understand potential benefits, the purpose of this study is to evaluate accuracy of two hydraulic fracture front algorithms, namely the one with Multi Layer Tip Elements (MuLTipEl) and Implicit Level Set Algorithm (ILSA). Both of these algorithms use the tip asymptotic solution to advance the fracture front, but use very different logic underneath. A series of benchmarking numerical examples with various meshes and the degree of complexity is performed to reveal advantages and limitations of these approaches.","PeriodicalId":418045,"journal":{"name":"Proceedings 56th US Rock Mechanics / Geomechanics Symposium","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115160393","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Several analytical solutions for the hydraulic diffusivity equation (HDE) in poroelastic reservoirs with constantpermeability are available in the petroleum engineering literature. Although, the mathematical modeling of the permeabilitypressure-sensitive effect through the nonlinear hydraulic diffusivity equation (NHDE) still constitutes a challenge in the petroleumindustry. This work presents a new transient two-dimensional (2-D) analytical model for oil flow in an infinite permeability-hysteretic pressure-sensitive reservoir during alternating loading/unloading cycles. Two new hydraulic diffusivity deviator factorsare presented for drawdown and build-up periods in order to represent the permeability deviation during the drawdown and itspartial restoration in the build-up period. When the well is open to flow, the results show clearly the permeability deviationcompared to the linear solution (constant permeability), as well as, when the well is shut, the hysteresis-response is also noticedon the diagnostic plots. The model calibration is performed by a numerical oil flow simulator, widely used in the reservoirengineering literature. The accuracy, ease of implementation, and low computational costs constitute the main advantages relatedto the developed model. Therewith it may be a useful and attractive mathematical tool to support the well-reservoir performancemanagement.
{"title":"Analytical Model for Mechanical Formation Damage Control in Permeability-Hysteretic Oil Reservoirs","authors":"F. Fernandes","doi":"10.56952/arma-2022-0014","DOIUrl":"https://doi.org/10.56952/arma-2022-0014","url":null,"abstract":"Several analytical solutions for the hydraulic diffusivity equation (HDE) in poroelastic reservoirs with constantpermeability are available in the petroleum engineering literature. Although, the mathematical modeling of the permeabilitypressure-sensitive effect through the nonlinear hydraulic diffusivity equation (NHDE) still constitutes a challenge in the petroleumindustry. This work presents a new transient two-dimensional (2-D) analytical model for oil flow in an infinite permeability-hysteretic pressure-sensitive reservoir during alternating loading/unloading cycles. Two new hydraulic diffusivity deviator factorsare presented for drawdown and build-up periods in order to represent the permeability deviation during the drawdown and itspartial restoration in the build-up period. When the well is open to flow, the results show clearly the permeability deviationcompared to the linear solution (constant permeability), as well as, when the well is shut, the hysteresis-response is also noticedon the diagnostic plots. The model calibration is performed by a numerical oil flow simulator, widely used in the reservoirengineering literature. The accuracy, ease of implementation, and low computational costs constitute the main advantages relatedto the developed model. Therewith it may be a useful and attractive mathematical tool to support the well-reservoir performancemanagement.","PeriodicalId":418045,"journal":{"name":"Proceedings 56th US Rock Mechanics / Geomechanics Symposium","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123118774","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Guillaume Sasseville, Pascal Turcotte, V. Falmagne
The LaRonde mine is a world-class deposit of gold-copper and zinc-silver along the Cadillac Fault in the Abitibi-Témiscamingue region of Quebec, Canada. Since its inauguration in 1988, the LaRonde mine has produced over 7 M ounces of gold. Mining operations currently extend 3.2 km below the surface with plans to reach 3.4 km. The LaRonde mine has been dealing with induced seismicity daily since 2003. The seismic activity can exceed MRichter 2, and the pro-active management of seismic risk is a key element to operate this mine at that depth and under these seismically active conditions.Seismic risk at the LaRonde mine is currently managed through a combination of control measures, including a ground-control-driven mining sequence and level design, dynamic ground support systems, and procedures to limit workforce exposure. These control measures have evolved over time and been adapted to the seismic risk as the operation becomes deeper and larger. The main objective is to maintain a safe work environment while meeting production requirements.Seismic risk management is an ongoing concern at the LaRonde mine. This paper presents the current state of the strategic and tactical control measures implemented on site to manage seismic risk at the LaRonde mine, and it documents some of the impacts on operational flexibility and performance. The effectiveness of control measures must be quantified to measure improvements year after year and to identify and correct observed deficiencies.
{"title":"Control Measures to Manage Seismic Risk at the LaRonde Mine, a Deep and Seismically Active Operation","authors":"Guillaume Sasseville, Pascal Turcotte, V. Falmagne","doi":"10.56952/arma-2022-0625","DOIUrl":"https://doi.org/10.56952/arma-2022-0625","url":null,"abstract":"The LaRonde mine is a world-class deposit of gold-copper and zinc-silver along the Cadillac Fault in the Abitibi-Témiscamingue region of Quebec, Canada. Since its inauguration in 1988, the LaRonde mine has produced over 7 M ounces of gold. Mining operations currently extend 3.2 km below the surface with plans to reach 3.4 km. The LaRonde mine has been dealing with induced seismicity daily since 2003. The seismic activity can exceed MRichter 2, and the pro-active management of seismic risk is a key element to operate this mine at that depth and under these seismically active conditions.Seismic risk at the LaRonde mine is currently managed through a combination of control measures, including a ground-control-driven mining sequence and level design, dynamic ground support systems, and procedures to limit workforce exposure. These control measures have evolved over time and been adapted to the seismic risk as the operation becomes deeper and larger. The main objective is to maintain a safe work environment while meeting production requirements.Seismic risk management is an ongoing concern at the LaRonde mine. This paper presents the current state of the strategic and tactical control measures implemented on site to manage seismic risk at the LaRonde mine, and it documents some of the impacts on operational flexibility and performance. The effectiveness of control measures must be quantified to measure improvements year after year and to identify and correct observed deficiencies.","PeriodicalId":418045,"journal":{"name":"Proceedings 56th US Rock Mechanics / Geomechanics Symposium","volume":"68 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125203848","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A simple testing apparatus has been designed for measurement of tensile strength of rock and characterization of fracture parameters such as critical crack opening displacement. The apparatus is a hardened-steel beam with a notch and a cut-out, designed so that the rock specimen is subjected to uniform stress through its thickness with negligible bending. The dimensions of the apparatus are length = 280.0 mm, height = 100.0 mm, and thickness = 26.5 mm; the notch length = 60.0 mm and width = 2.0 mm. Two strain gages, SG 1 and 2, are attached near the notch tip and the apparatus is calibrated to provide the tensile stress in the specimen. A Charcoal granite specimen with side notches at its center was used for testing within a closed-loop, servo-hydraulic load with crack opening displacement (COD) at a rate of 0.02 micron/s used as the feedback signal. The rock specimen was attached to the bottom cut-out using an epoxy adhesive. Two strain gages were installed on the rock surface close to the notch tips. Digital image correlation (DIC) was used to investigate the displacement field and the symmetry of displacement along the ligament length. The crack initiation and propagation in the post-peak regime is discussed using the data from the strain gages and DIC. The results show that the apparatus can be used to investigate post-peak response and critical crack opening displacement of a brittle rock.
{"title":"Critical crack opening of Charcoal granite","authors":"A. Fakhimi, Poyan Asem, A. Tarokh, J. Labuz","doi":"10.56952/arma-2022-0447","DOIUrl":"https://doi.org/10.56952/arma-2022-0447","url":null,"abstract":"A simple testing apparatus has been designed for measurement of tensile strength of rock and characterization of fracture parameters such as critical crack opening displacement. The apparatus is a hardened-steel beam with a notch and a cut-out, designed so that the rock specimen is subjected to uniform stress through its thickness with negligible bending. The dimensions of the apparatus are length = 280.0 mm, height = 100.0 mm, and thickness = 26.5 mm; the notch length = 60.0 mm and width = 2.0 mm. Two strain gages, SG 1 and 2, are attached near the notch tip and the apparatus is calibrated to provide the tensile stress in the specimen. A Charcoal granite specimen with side notches at its center was used for testing within a closed-loop, servo-hydraulic load with crack opening displacement (COD) at a rate of 0.02 micron/s used as the feedback signal. The rock specimen was attached to the bottom cut-out using an epoxy adhesive. Two strain gages were installed on the rock surface close to the notch tips. Digital image correlation (DIC) was used to investigate the displacement field and the symmetry of displacement along the ligament length. The crack initiation and propagation in the post-peak regime is discussed using the data from the strain gages and DIC. The results show that the apparatus can be used to investigate post-peak response and critical crack opening displacement of a brittle rock.","PeriodicalId":418045,"journal":{"name":"Proceedings 56th US Rock Mechanics / Geomechanics Symposium","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127453200","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. M. Padilla, E. Rougier, E. Knight, M. R. Reda Taha, J. Stormont
Numerical modeling techniques using the combined finite-discrete element method have been utilized to explore the relationship between stress, damage, and crack propagation in concrete. Obtaining post-peak behavior from the Brazilian tension test is difficult because failure occurs abruptly. An experimental test method is described which enables monitoring of the post-peak cracking behavior in the Brazilian tension test by slowing the crack propagation. Experimental testing with this technique proved its capabilities in slowing crack propagation. The combined finite-discrete element method is used to further examine the stress states during this test and to understand the damage evolution present in this test prior to the peak strength. The method also allows for interpretation into the type of damage present throughout the entire test and the zones in which that damage initiates. A comparison is also performed between the numerical results and experimental observations to determine how well the numerical method captures the experimental results. This work enables a good understanding of how fractures form in the Brazilian tension test as well as a comparison between experimental and numerical technique results.
{"title":"Concrete Fracture and Stress Analysis using the Combined Finite-Discrete Element Method in the Brazilian Tension Test","authors":"A. M. Padilla, E. Rougier, E. Knight, M. R. Reda Taha, J. Stormont","doi":"10.56952/arma-2022-0465","DOIUrl":"https://doi.org/10.56952/arma-2022-0465","url":null,"abstract":"Numerical modeling techniques using the combined finite-discrete element method have been utilized to explore the relationship between stress, damage, and crack propagation in concrete. Obtaining post-peak behavior from the Brazilian tension test is difficult because failure occurs abruptly. An experimental test method is described which enables monitoring of the post-peak cracking behavior in the Brazilian tension test by slowing the crack propagation. Experimental testing with this technique proved its capabilities in slowing crack propagation. The combined finite-discrete element method is used to further examine the stress states during this test and to understand the damage evolution present in this test prior to the peak strength. The method also allows for interpretation into the type of damage present throughout the entire test and the zones in which that damage initiates. A comparison is also performed between the numerical results and experimental observations to determine how well the numerical method captures the experimental results. This work enables a good understanding of how fractures form in the Brazilian tension test as well as a comparison between experimental and numerical technique results.","PeriodicalId":418045,"journal":{"name":"Proceedings 56th US Rock Mechanics / Geomechanics Symposium","volume":"57 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124812047","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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