Flow and transport properties of fractured crystalline rock are of great interest for different geotechnical ap-plications,such as storage of carbon dioxide,extraction of geothermal energy,or geologic storage of hazar...Flow and transport properties of fractured crystalline rock are of great interest for different geotechnical ap-plications,such as storage of carbon dioxide,extraction of geothermal energy,or geologic storage of hazardous waste.For the long-term safety assessment of geological storage of hazardous waste,the understanding of flow and transport properties through the network of fractures is essential.The flow and transport behaviour can be explored using numerical models to investigate what parameters that affect the results.In this work a pilot study is carried out for multiple realizations of single realistic fractures,using fractal theories,which then are nu-merically sheared using a semi-analytical algorithm.The aperture field is calculated using the average distance of the volume integral of the void that a 1 mm lateral displacement of the sheared surfaces generates.The flow field through the aperture field is solved using Reynolds lubrication equation in linear triangular finite elements.The transport properties,travel length,travel time,transport resistance and specific flow wetted surface,are calculated in a Lagrangian framework using 10,000 particles for each of the 128 flow fields.Evaluating these four metrics,varying initial roughness,4<JRC<10 and normal stress between 0.2 and 20 MPa during shearing,it is concluded that an increase in normal stress generally results in longer travel paths,longer travel times,higher transport resistance and larger specific flow wetted surface while an increase of initial roughness will generally result in longer travel paths,shorter travel times,lower transport resistance and smaller specific flow wetted surface.展开更多
This study presents a calibration process of three-dimensional particle flow code(PFC3D)simulation of intact and fissured granite samples.First,laboratory stressestrain response from triaxial testing of intact and fis...This study presents a calibration process of three-dimensional particle flow code(PFC3D)simulation of intact and fissured granite samples.First,laboratory stressestrain response from triaxial testing of intact and fissured granite samples is recalled.Then,PFC3D is introduced,with focus on the bonded particle models(BPM).After that,we present previous studies where intact rock is simulated by means of flatjoint approaches,and how improved accuracy was gained with the help of parametric studies.Then,models of the pre-fissured rock specimens were generated,including modeled fissures in the form of“smooth joint”type contacts.Finally,triaxial testing simulations of 1 t 2 and 2 t 3 jointed rock specimens were performed.Results show that both elastic behavior and the peak strength levels are closely matched,without any additional fine tuning of micro-mechanical parameters.Concerning the postfailure behavior,models reproduce the trends of decreasing dilation with increasing confinement and plasticity.However,the dilation values simulated are larger than those observed in practice.This is attributed to the difficulty in modeling some phenomena of fissured rock behaviors,such as rock piece corner crushing with dust production and interactions between newly formed shear bands or axial splitting cracks with pre-existing joints.展开更多
Since each rock joint is unique by nature,the utilization of replicas in direct shear testing is required to carry out experimental parameter studies.However,information about the ability of the replicas to simulate t...Since each rock joint is unique by nature,the utilization of replicas in direct shear testing is required to carry out experimental parameter studies.However,information about the ability of the replicas to simulate the shear mechanical behavior of the rock joint and their dispersion in direct shear testing is lacking.With the aim to facilitate generation of high-quality direct shear test data from replicas,a novel component in the testing procedure is introduced by presenting two parameters for geometric quality assurance.The parameters are derived from surface comparisons of three-dimensional(3D)scanning data of the rock joint and its replicas.The first parameter,smf,captures morphological deviations between the replica and the rock joint surfaces.smf is derived as the standard deviation of the deviations between the coordinate points of the replica and the rock joint.Four sources of errors introduced in the replica manufacturing process employed in this study could be identified.These errors could be minimized,yielding replicas with smf0.06 mm.The second parameter is a vector,VHp100,which describes deviations with respect to the shear direction.It is the projection of the 100 mm long normal vector of the best-fit plane of the replica joint surface to the corresponding plane of the rock joint.VHp100was found to be less than or equal to 0.36 mm in this study.Application of these two geometric quality assurance parameters demonstrates that it is possible to manufacture replicas with high geometric similarity to the rock joint.In a subsequent paper(part 2),smf and VHp100 are incorporated in a novel quality assurance method,in which the parameters shall be evaluated prior to direct shear testing.Replicas having parameter values below established thresholds shall have a known and narrow dispersion and imitate the shear mechanical behavior of the rock joint.展开更多
Macbeth was wary when he heard the witches out. He deliberated. He dithered. And Lady Macbeth puckered his courage up to the hilt and egged him on to murder. Macbeth murdered. Then he balked. He hallucinated himself o...Macbeth was wary when he heard the witches out. He deliberated. He dithered. And Lady Macbeth puckered his courage up to the hilt and egged him on to murder. Macbeth murdered. Then he balked. He hallucinated himself out of his wits. Then he went on a rampage to save his own skin. He destroyed in fear of being destroyed. Yet all he ended up doing is losing his peace, his composure, his wife, and finally, his life. The whole of Operation Kingship, if the author may so call the whole business of eliminating Duncan out of the way of the royal throne, failed miserably. Macbeth, on the lookout for power found himself terribly, fearfully beaten, crestfallen, devastated. The million-dollar question then is -what is it that went so very wrong in the whole process？ Critics are often heard to cry his ambition--his ＂overvaulting ambition＂ down as his incorrigible hamartia. But living in the 21st century, one gets to hear that ambition is not bad after all--the higher the ＂ambi-horse＂ vaults, the higher the chances of success is. In this dissertation, the author proposes to analyze Macbeth＇s case from the perspective of management studies. This paper, more than setting forth a literary statement of Macbeth＇s predicament, aims at what management Gurus would love to call a candid SWOT （strength, weakness, opportunity, threat） and STEEPLED （social, technological, economic, educational, political, legal, environmental, and demographic factors） analysis of Macbeth＇s situation to find out where the shoe pinched, whether the whole project crashed because of inefficient leadership, or whether there was no leadership at all, whether organizational strategies were not properly formulated or whether the implementation capsized horribly, thereby making the whole business a rudderless wild goose chase. The discussion necessarily follows up with an insight into what Macbeth lacked as far as Maslow＇s Pyramid of Needs is concerned and what it could have been like, had it been rewritten with a corporate-friendly, management-savvy 21st century protagonist armed with well formulated action plans and stronger inter-personal skills, in the titular lead.展开更多
Each rock joint is unique by nature which means that utilization of replicas in direct shear tests is required in experimental parameter studies.However,a method to acquire knowledge about the ability of the replicas ...Each rock joint is unique by nature which means that utilization of replicas in direct shear tests is required in experimental parameter studies.However,a method to acquire knowledge about the ability of the replicas to imitate the shear mechanical behavior of the rock joint and their dispersion in direct shear testing is lacking.In this study,a novel method is presented for geometric quality assurance of replicas.The aim is to facilitate generation of high-quality direct shear testing data as a prerequisite for reliable subsequent analyses of the results.In Part 1 of this study,two quality assurance parameters,smf and V_(Hp100),are derived and their usefulness for evaluation of geometric deviations,i.e.geometric reproducibility,is shown.In Part 2,the parameters are validated by showing a correlation between the parameters and the shear mechanical behavior,which qualifies the parameters for usage in the quality assurance method.Unique results from direct shear tests presenting comparisons between replicas and the rock joint show that replicas fulfilling proposed threshold values of σ_(mf)<0.06 mm and|V_(Hp100)|<0.2 mm have a narrow dispersion and imitate the shear mechanical behavior of the rock joint in all aspects apart from having a slightly lower peak shear strength.The wear in these replicas,which have similar morphology as the rock joint,is in the same areas as in the rock joint.The wear is slightly larger in the rock joint and therefore the discrepancy in peak shear strength derives from differences in material properties,possibly from differences in toughness.It is shown by application of the suggested method that the quality assured replicas manufactured following the process employed in this study phenomenologically capture the shear strength characteristics,which makes them useful in parameter studies.展开更多
文摘Flow and transport properties of fractured crystalline rock are of great interest for different geotechnical ap-plications,such as storage of carbon dioxide,extraction of geothermal energy,or geologic storage of hazardous waste.For the long-term safety assessment of geological storage of hazardous waste,the understanding of flow and transport properties through the network of fractures is essential.The flow and transport behaviour can be explored using numerical models to investigate what parameters that affect the results.In this work a pilot study is carried out for multiple realizations of single realistic fractures,using fractal theories,which then are nu-merically sheared using a semi-analytical algorithm.The aperture field is calculated using the average distance of the volume integral of the void that a 1 mm lateral displacement of the sheared surfaces generates.The flow field through the aperture field is solved using Reynolds lubrication equation in linear triangular finite elements.The transport properties,travel length,travel time,transport resistance and specific flow wetted surface,are calculated in a Lagrangian framework using 10,000 particles for each of the 128 flow fields.Evaluating these four metrics,varying initial roughness,4<JRC<10 and normal stress between 0.2 and 20 MPa during shearing,it is concluded that an increase in normal stress generally results in longer travel paths,longer travel times,higher transport resistance and larger specific flow wetted surface while an increase of initial roughness will generally result in longer travel paths,shorter travel times,lower transport resistance and smaller specific flow wetted surface.
基金The University of Vigo is acknowledged for financing part of the first author’s PhD studiesthe Spanish Ministry of Economy and Competitiveness for funding of the project‘Deepening on the behaviour of rock masses:Scale effects on the stressestrain response of fissured rock samples with particular emphasis on post-failure’,awarded under Contract Reference No.RTI2018-093563-B-I00partially financed by means of European Regional Development Funds from the European Union(EU)。
文摘This study presents a calibration process of three-dimensional particle flow code(PFC3D)simulation of intact and fissured granite samples.First,laboratory stressestrain response from triaxial testing of intact and fissured granite samples is recalled.Then,PFC3D is introduced,with focus on the bonded particle models(BPM).After that,we present previous studies where intact rock is simulated by means of flatjoint approaches,and how improved accuracy was gained with the help of parametric studies.Then,models of the pre-fissured rock specimens were generated,including modeled fissures in the form of“smooth joint”type contacts.Finally,triaxial testing simulations of 1 t 2 and 2 t 3 jointed rock specimens were performed.Results show that both elastic behavior and the peak strength levels are closely matched,without any additional fine tuning of micro-mechanical parameters.Concerning the postfailure behavior,models reproduce the trends of decreasing dilation with increasing confinement and plasticity.However,the dilation values simulated are larger than those observed in practice.This is attributed to the difficulty in modeling some phenomena of fissured rock behaviors,such as rock piece corner crushing with dust production and interactions between newly formed shear bands or axial splitting cracks with pre-existing joints.
文摘Since each rock joint is unique by nature,the utilization of replicas in direct shear testing is required to carry out experimental parameter studies.However,information about the ability of the replicas to simulate the shear mechanical behavior of the rock joint and their dispersion in direct shear testing is lacking.With the aim to facilitate generation of high-quality direct shear test data from replicas,a novel component in the testing procedure is introduced by presenting two parameters for geometric quality assurance.The parameters are derived from surface comparisons of three-dimensional(3D)scanning data of the rock joint and its replicas.The first parameter,smf,captures morphological deviations between the replica and the rock joint surfaces.smf is derived as the standard deviation of the deviations between the coordinate points of the replica and the rock joint.Four sources of errors introduced in the replica manufacturing process employed in this study could be identified.These errors could be minimized,yielding replicas with smf0.06 mm.The second parameter is a vector,VHp100,which describes deviations with respect to the shear direction.It is the projection of the 100 mm long normal vector of the best-fit plane of the replica joint surface to the corresponding plane of the rock joint.VHp100was found to be less than or equal to 0.36 mm in this study.Application of these two geometric quality assurance parameters demonstrates that it is possible to manufacture replicas with high geometric similarity to the rock joint.In a subsequent paper(part 2),smf and VHp100 are incorporated in a novel quality assurance method,in which the parameters shall be evaluated prior to direct shear testing.Replicas having parameter values below established thresholds shall have a known and narrow dispersion and imitate the shear mechanical behavior of the rock joint.
文摘Macbeth was wary when he heard the witches out. He deliberated. He dithered. And Lady Macbeth puckered his courage up to the hilt and egged him on to murder. Macbeth murdered. Then he balked. He hallucinated himself out of his wits. Then he went on a rampage to save his own skin. He destroyed in fear of being destroyed. Yet all he ended up doing is losing his peace, his composure, his wife, and finally, his life. The whole of Operation Kingship, if the author may so call the whole business of eliminating Duncan out of the way of the royal throne, failed miserably. Macbeth, on the lookout for power found himself terribly, fearfully beaten, crestfallen, devastated. The million-dollar question then is -what is it that went so very wrong in the whole process？ Critics are often heard to cry his ambition--his ＂overvaulting ambition＂ down as his incorrigible hamartia. But living in the 21st century, one gets to hear that ambition is not bad after all--the higher the ＂ambi-horse＂ vaults, the higher the chances of success is. In this dissertation, the author proposes to analyze Macbeth＇s case from the perspective of management studies. This paper, more than setting forth a literary statement of Macbeth＇s predicament, aims at what management Gurus would love to call a candid SWOT （strength, weakness, opportunity, threat） and STEEPLED （social, technological, economic, educational, political, legal, environmental, and demographic factors） analysis of Macbeth＇s situation to find out where the shoe pinched, whether the whole project crashed because of inefficient leadership, or whether there was no leadership at all, whether organizational strategies were not properly formulated or whether the implementation capsized horribly, thereby making the whole business a rudderless wild goose chase. The discussion necessarily follows up with an insight into what Macbeth lacked as far as Maslow＇s Pyramid of Needs is concerned and what it could have been like, had it been rewritten with a corporate-friendly, management-savvy 21st century protagonist armed with well formulated action plans and stronger inter-personal skills, in the titular lead.
文摘Each rock joint is unique by nature which means that utilization of replicas in direct shear tests is required in experimental parameter studies.However,a method to acquire knowledge about the ability of the replicas to imitate the shear mechanical behavior of the rock joint and their dispersion in direct shear testing is lacking.In this study,a novel method is presented for geometric quality assurance of replicas.The aim is to facilitate generation of high-quality direct shear testing data as a prerequisite for reliable subsequent analyses of the results.In Part 1 of this study,two quality assurance parameters,smf and V_(Hp100),are derived and their usefulness for evaluation of geometric deviations,i.e.geometric reproducibility,is shown.In Part 2,the parameters are validated by showing a correlation between the parameters and the shear mechanical behavior,which qualifies the parameters for usage in the quality assurance method.Unique results from direct shear tests presenting comparisons between replicas and the rock joint show that replicas fulfilling proposed threshold values of σ_(mf)<0.06 mm and|V_(Hp100)|<0.2 mm have a narrow dispersion and imitate the shear mechanical behavior of the rock joint in all aspects apart from having a slightly lower peak shear strength.The wear in these replicas,which have similar morphology as the rock joint,is in the same areas as in the rock joint.The wear is slightly larger in the rock joint and therefore the discrepancy in peak shear strength derives from differences in material properties,possibly from differences in toughness.It is shown by application of the suggested method that the quality assured replicas manufactured following the process employed in this study phenomenologically capture the shear strength characteristics,which makes them useful in parameter studies.
