The Experts below are selected from a list of 2124 Experts worldwide ranked by ideXlab platform
Paul Augustinus - One of the best experts on this subject based on the ideXlab platform.
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glacial valley cross profile development the influence of in situ Rock stress and Rock Mass Strength with examples from the southern alps new zealand
Geomorphology, 1995Co-Authors: Paul AugustinusAbstract:Abstract The evolution of the glacial valley cross-profile form is commonly attributed primarily to the glaciological variables that control the erosion of the channel. However, studies in the New Zealand Southern Alps suggest that the Rock Mass Strength (RMS) of the eroded Rock Mass is a major control on slope stability, and hence on the final form of the trough. RMS of the slope Rock will alter with time and erosional excavation and oversteepening of the valley slopes. The in situ Rock stress field induced by: (1) the extreme topography in the axial ranges of the New Zealand Southern Alps, and (2) tectonically by collision of the Australian and Pacific crustal plates, may play a role in valley slope development by controlling the location of Rock failure and reducing RMS. This provides weakened Rock that may provide sites for selective glacial erosion of the Rock Mass. Hence, valley form evolution models should also take into account the RMS and the in situ stress field acting in the eroded Rock Mass. This study has implications for the development and modification of alpine glacial troughs in similar tectonic settings elsewhere.
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the influence of Rock Mass Strength on glacial valley cross profile morphometry a case study from the southern alps new zealand
Earth Surface Processes and Landforms, 1992Co-Authors: Paul AugustinusAbstract:The erosional morphology in the vicinity of the Main Divide of the Southern Alps, and Fiordland, New Zealand, appears to be a product of the interaction between Alpine Fault-induced tectonic processes, Rock Mass Strength of the uplifted and eroded bedRock, and the processes acting to denude the developing mountain landscape. The magnitude of the effects of glacial erosion on the landscape is directly controlled by the size and physical properties of the glaciers, whilst the form of the trough is a direct consequence of the Rock Mass Strength (RMS) properties of the slope Rock. Realistic models of development of the cross-profile shape of glacial valleys must take into consideration the RMS properties of the eroded substrate.
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The influence of Rock Mass Strength on glacial valley cross‐profile morphometry: A case study from the Southern Alps, New Zealand
Earth Surface Processes and Landforms, 1992Co-Authors: Paul AugustinusAbstract:The erosional morphology in the vicinity of the Main Divide of the Southern Alps, and Fiordland, New Zealand, appears to be a product of the interaction between Alpine Fault-induced tectonic processes, Rock Mass Strength of the uplifted and eroded bedRock, and the processes acting to denude the developing mountain landscape. The magnitude of the effects of glacial erosion on the landscape is directly controlled by the size and physical properties of the glaciers, whilst the form of the trough is a direct consequence of the Rock Mass Strength (RMS) properties of the slope Rock. Realistic models of development of the cross-profile shape of glacial valleys must take into consideration the RMS properties of the eroded substrate.
Doug Stead - One of the best experts on this subject based on the ideXlab platform.
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Fault controls spatial variation of fracture density and Rock Mass Strength within the Yarlung Tsangpo Fault damage zone (southern Tibet)
2020Co-Authors: Xueliang Wang, Doug Stead, Giovanni B. Crosta, Shengwen Qi, Paolo FrattiniAbstract:Quantifying the relationship between faulting and the spatial geometrical and mechanical characteristics of a Rock Mass controlled by faulting is difficult, mainly because of varying lithology and Rock Mass characteristics, the effects of topography and vegetation and local erosion of weaker Rock Mass. In this study, the procedures, investigation approaches, evidence and criteria for defining the threshold distance for damage zones of Yarlung Tsangpo (YLTP) Fault of southern Tibet were studied quantitatively by combining the spatial variations of fracture density, Rock Mass Strength, Rockfall inventory and previous thermal evidence. The extent of threshold distance of damage zone of the YLTP Fault is estimated at 5.9±0.6km. The internal dynamic action of fault controls Rock Mass physical and mechanical properties in the study area. The fault first affects the characteristics of Rock Mass structures, and then the orientation of the Rock structures influences the stability of slope leading to Rockfall.
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An Integrated Numerical Modelling–Discrete Fracture Network Approach Applied to the Characterisation of Rock Mass Strength of Naturally Fractured Pillars
Rock Mechanics and Rock Engineering, 2010Co-Authors: Davide Elmo, Doug SteadAbstract:Naturally fractured mine pillars provide an excellent example of the importance of accurately determining Rock Mass Strength. Failure in slender pillars is predominantly controlled by naturally occurring discontinuities, their influence diminishing with increasing pillar width, with wider pillars failing through a combination of brittle and shearing processes. To accurately simulate this behaviour by numerical modelling, the current analysis incorporates a more realistic representation of the mechanical behaviour of discrete fracture systems. This involves realistic simulation and representation of fracture networks, either as individual entities or as a collective system of fracture sets, or a combination of both. By using an integrated finite element/discrete element–discrete fracture network approach it is possible to study the failure of Rock Masses in tension and compression, along both existing pre-existing fractures and through intact Rock bridges, and incorporating complex kinematic mechanisms. The proposed modelling approach fully captures the anisotropic and inhomogeneous effects of natural jointing and is considered to be more realistic than methods relying solely on continuum or discontinuum representation. The paper concludes with a discussion on the development of synthetic Rock Mass properties, with the intention of providing a more robust link between Rock Mass Strength and Rock Mass classification systems.
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an integrated numerical modelling discrete fracture network approach applied to the characterisation of Rock Mass Strength of naturally fractured pillars
Rock Mechanics and Rock Engineering, 2010Co-Authors: Davide Elmo, Doug SteadAbstract:Naturally fractured mine pillars provide an excellent example of the importance of accurately determining Rock Mass Strength. Failure in slender pillars is predominantly controlled by naturally occurring discontinuities, their influence diminishing with increasing pillar width, with wider pillars failing through a combination of brittle and shearing processes. To accurately simulate this behaviour by numerical modelling, the current analysis incorporates a more realistic representation of the mechanical behaviour of discrete fracture systems. This involves realistic simulation and representation of fracture networks, either as individual entities or as a collective system of fracture sets, or a combination of both. By using an integrated finite element/discrete element–discrete fracture network approach it is possible to study the failure of Rock Masses in tension and compression, along both existing pre-existing fractures and through intact Rock bridges, and incorporating complex kinematic mechanisms. The proposed modelling approach fully captures the anisotropic and inhomogeneous effects of natural jointing and is considered to be more realistic than methods relying solely on continuum or discontinuum representation. The paper concludes with a discussion on the development of synthetic Rock Mass properties, with the intention of providing a more robust link between Rock Mass Strength and Rock Mass classification systems.
Davide Elmo - One of the best experts on this subject based on the ideXlab platform.
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An Integrated Numerical Modelling–Discrete Fracture Network Approach Applied to the Characterisation of Rock Mass Strength of Naturally Fractured Pillars
Rock Mechanics and Rock Engineering, 2010Co-Authors: Davide Elmo, Doug SteadAbstract:Naturally fractured mine pillars provide an excellent example of the importance of accurately determining Rock Mass Strength. Failure in slender pillars is predominantly controlled by naturally occurring discontinuities, their influence diminishing with increasing pillar width, with wider pillars failing through a combination of brittle and shearing processes. To accurately simulate this behaviour by numerical modelling, the current analysis incorporates a more realistic representation of the mechanical behaviour of discrete fracture systems. This involves realistic simulation and representation of fracture networks, either as individual entities or as a collective system of fracture sets, or a combination of both. By using an integrated finite element/discrete element–discrete fracture network approach it is possible to study the failure of Rock Masses in tension and compression, along both existing pre-existing fractures and through intact Rock bridges, and incorporating complex kinematic mechanisms. The proposed modelling approach fully captures the anisotropic and inhomogeneous effects of natural jointing and is considered to be more realistic than methods relying solely on continuum or discontinuum representation. The paper concludes with a discussion on the development of synthetic Rock Mass properties, with the intention of providing a more robust link between Rock Mass Strength and Rock Mass classification systems.
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an integrated numerical modelling discrete fracture network approach applied to the characterisation of Rock Mass Strength of naturally fractured pillars
Rock Mechanics and Rock Engineering, 2010Co-Authors: Davide Elmo, Doug SteadAbstract:Naturally fractured mine pillars provide an excellent example of the importance of accurately determining Rock Mass Strength. Failure in slender pillars is predominantly controlled by naturally occurring discontinuities, their influence diminishing with increasing pillar width, with wider pillars failing through a combination of brittle and shearing processes. To accurately simulate this behaviour by numerical modelling, the current analysis incorporates a more realistic representation of the mechanical behaviour of discrete fracture systems. This involves realistic simulation and representation of fracture networks, either as individual entities or as a collective system of fracture sets, or a combination of both. By using an integrated finite element/discrete element–discrete fracture network approach it is possible to study the failure of Rock Masses in tension and compression, along both existing pre-existing fractures and through intact Rock bridges, and incorporating complex kinematic mechanisms. The proposed modelling approach fully captures the anisotropic and inhomogeneous effects of natural jointing and is considered to be more realistic than methods relying solely on continuum or discontinuum representation. The paper concludes with a discussion on the development of synthetic Rock Mass properties, with the intention of providing a more robust link between Rock Mass Strength and Rock Mass classification systems.
Tao Xu - One of the best experts on this subject based on the ideXlab platform.
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Estimating in situ Rock Mass Strength and elastic modulus of granite from the Soultz-sous-Forêts geothermal reservoir (France)
Geothermal Energy, 2018Co-Authors: Marlène C. Villeneuve, Alexandra R. L. Kushnir, Patrick Baud, Guanglei Zhou, Michael J. Heap, Tao Qin, Tao XuAbstract:Knowledge of the Strength and elastic modulus of a reservoir Rock is important for the optimisation of a particular geothermal resource. The reservoir Rock for many geothermal projects in the Upper Rhine Graben, such as those at Soultz-sous-Forêts and Rittershoffen (both France), is porphyritic granite. High fracture densities (up to ~ 30 fractures/m) in this reservoir Rock require that we consider the Strength and elastic modulus of the Rock Mass, rather than the intact Rock. Here we use uniaxial and triaxial deformation experiments performed on intact Rock coupled with Geological Strength Index assessments—using the wealth of information from core and borehole analyses—to provide Rock Mass Strength and elastic modulus estimates for the granite reservoir at Soultz-sous-Forêts (from a depth of 1400 to 2200 m) using the generalised Hoek–Brown failure criterion. The average uniaxial compressive Strength and elastic modulus of the intact granite are 140 MPa (this study) and 40 GPa (data from this study and the literature), respectively. The modelled Strength of the intact granite is 360 MPa at a depth of 1400 m and increases to 455 MPa at 2200 m (using our estimate for the empirical m _ i term of 30, determined using triaxial and tensile Strength measurements on the intact granite). Strength of the Rock Mass varies in accordance with the fracture density and the extent and nature of the fracture infill, reaching lows of ~ 40–50 MPa (in, for example, the densely fractured zones in EPS-1 at depths of ~ 1650 and ~ 2160 m, respectively) and highs of above 400 MPa (in, for example, the largely unfractured zone at a depth of ~ 1940–2040 m). Variations in Rock Mass elastic modulus are qualitatively similar (values vary from 1 to 2 GPa up to the elastic modulus of the intact Rock, 40 GPa). Our study highlights that macrofractures and joints reduce Rock Mass Strength and should be considered when assessing the Rock Mass for well stability and Rock Mass deformation due to stress redistribution in the reservoir. We present a case study to demonstrate how a simple and cost-effective engineering method can be used to provide an indication of the in situ Strength and elastic modulus of reservoir Rock Masses, important for a wide range of modelling and stimulation strategies. We recommend that the effect of macrofractures on Rock Mass Strength and stiffness be validated for incorporation into geomechanical characterisation for geothermal reservoirs worldwide.
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estimating in situ Rock Mass Strength and elastic modulus of granite from the soultz sous forets geothermal reservoir france
Geothermal Energy, 2018Co-Authors: Marlène C. Villeneuve, Alexandra R. L. Kushnir, Patrick Baud, Guanglei Zhou, Michael J. Heap, Tao XuAbstract:Knowledge of the Strength and elastic modulus of a reservoir Rock is important for the optimisation of a particular geothermal resource. The reservoir Rock for many geothermal projects in the Upper Rhine Graben, such as those at Soultz-sous-Forets and Rittershoffen (both France), is porphyritic granite. High fracture densities (up to ~ 30 fractures/m) in this reservoir Rock require that we consider the Strength and elastic modulus of the Rock Mass, rather than the intact Rock. Here we use uniaxial and triaxial deformation experiments performed on intact Rock coupled with Geological Strength Index assessments—using the wealth of information from core and borehole analyses—to provide Rock Mass Strength and elastic modulus estimates for the granite reservoir at Soultz-sous-Forets (from a depth of 1400 to 2200 m) using the generalised Hoek–Brown failure criterion. The average uniaxial compressive Strength and elastic modulus of the intact granite are 140 MPa (this study) and 40 GPa (data from this study and the literature), respectively. The modelled Strength of the intact granite is 360 MPa at a depth of 1400 m and increases to 455 MPa at 2200 m (using our estimate for the empirical m i term of 30, determined using triaxial and tensile Strength measurements on the intact granite). Strength of the Rock Mass varies in accordance with the fracture density and the extent and nature of the fracture infill, reaching lows of ~ 40–50 MPa (in, for example, the densely fractured zones in EPS-1 at depths of ~ 1650 and ~ 2160 m, respectively) and highs of above 400 MPa (in, for example, the largely unfractured zone at a depth of ~ 1940–2040 m). Variations in Rock Mass elastic modulus are qualitatively similar (values vary from 1 to 2 GPa up to the elastic modulus of the intact Rock, 40 GPa). Our study highlights that macrofractures and joints reduce Rock Mass Strength and should be considered when assessing the Rock Mass for well stability and Rock Mass deformation due to stress redistribution in the reservoir. We present a case study to demonstrate how a simple and cost-effective engineering method can be used to provide an indication of the in situ Strength and elastic modulus of reservoir Rock Masses, important for a wide range of modelling and stimulation strategies. We recommend that the effect of macrofractures on Rock Mass Strength and stiffness be validated for incorporation into geomechanical characterisation for geothermal reservoirs worldwide.
Marlène C. Villeneuve - One of the best experts on this subject based on the ideXlab platform.
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Rock Mass properties and edifice Strength data from pinnacle ridge mt ruapehu new zealand
Journal of Volcanology and Geothermal Research, 2018Co-Authors: S P Mordensky, Marlène C. Villeneuve, Michael J. Heap, Jamie I Farquharson, Ben Kennedy, D M GravleyAbstract:Abstract Volcanic edifices exhibit spatially variable physical and mechanical properties. Magmatic intrusions are common at shallow depths within the volcanic edifice and are a poorly-understood contributor to this spatial variability. Intrusion-related alteration has been found to weaken Rock Mass Strength through the development of joints and fractures; however, there is a paucity of research investigating how intrusions affect Rock Mass Strength specific to the geotechnical units that define the Rock Masses. In this study, we employ a range of field techniques—field permeametry, Rock hardness assessment, Rock Mass classification, and discontinuity mapping—to characterise an exposed fossil geothermal system produced by a shallow intrusion at Pinnacle Ridge, Mt. Ruapehu (New Zealand). We find that intrusions detrimentally affect the Rock Mass characteristics of altered brecciated lava margins. The resulting change in Rock Mass Strength may be offset by an increase in intact Rock Strength as a product of alteration mineral precipitation in microfractures. Consequently, the final Strength of the Rock Mass of the altered brecciated lava margins has the potential to be lowest of any of the geotechnical units in the volcanic edifice. We also conclude that these discontinuities increase permeability of the host Rock at distances from the intrusion roughly proportional to 1–2 times the thickness of the intrusion itself under near-surface conditions. The data and conclusions presented in this study help to bridge the gap between the lab- and the field-scale and have immediate relevance to engineering geology and geothermal applications worldwide, and to Rock Mass classification assessments in volcanic environments.
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Estimating in situ Rock Mass Strength and elastic modulus of granite from the Soultz-sous-Forêts geothermal reservoir (France)
Geothermal Energy, 2018Co-Authors: Marlène C. Villeneuve, Alexandra R. L. Kushnir, Patrick Baud, Guanglei Zhou, Michael J. Heap, Tao Qin, Tao XuAbstract:Knowledge of the Strength and elastic modulus of a reservoir Rock is important for the optimisation of a particular geothermal resource. The reservoir Rock for many geothermal projects in the Upper Rhine Graben, such as those at Soultz-sous-Forêts and Rittershoffen (both France), is porphyritic granite. High fracture densities (up to ~ 30 fractures/m) in this reservoir Rock require that we consider the Strength and elastic modulus of the Rock Mass, rather than the intact Rock. Here we use uniaxial and triaxial deformation experiments performed on intact Rock coupled with Geological Strength Index assessments—using the wealth of information from core and borehole analyses—to provide Rock Mass Strength and elastic modulus estimates for the granite reservoir at Soultz-sous-Forêts (from a depth of 1400 to 2200 m) using the generalised Hoek–Brown failure criterion. The average uniaxial compressive Strength and elastic modulus of the intact granite are 140 MPa (this study) and 40 GPa (data from this study and the literature), respectively. The modelled Strength of the intact granite is 360 MPa at a depth of 1400 m and increases to 455 MPa at 2200 m (using our estimate for the empirical m _ i term of 30, determined using triaxial and tensile Strength measurements on the intact granite). Strength of the Rock Mass varies in accordance with the fracture density and the extent and nature of the fracture infill, reaching lows of ~ 40–50 MPa (in, for example, the densely fractured zones in EPS-1 at depths of ~ 1650 and ~ 2160 m, respectively) and highs of above 400 MPa (in, for example, the largely unfractured zone at a depth of ~ 1940–2040 m). Variations in Rock Mass elastic modulus are qualitatively similar (values vary from 1 to 2 GPa up to the elastic modulus of the intact Rock, 40 GPa). Our study highlights that macrofractures and joints reduce Rock Mass Strength and should be considered when assessing the Rock Mass for well stability and Rock Mass deformation due to stress redistribution in the reservoir. We present a case study to demonstrate how a simple and cost-effective engineering method can be used to provide an indication of the in situ Strength and elastic modulus of reservoir Rock Masses, important for a wide range of modelling and stimulation strategies. We recommend that the effect of macrofractures on Rock Mass Strength and stiffness be validated for incorporation into geomechanical characterisation for geothermal reservoirs worldwide.
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estimating in situ Rock Mass Strength and elastic modulus of granite from the soultz sous forets geothermal reservoir france
Geothermal Energy, 2018Co-Authors: Marlène C. Villeneuve, Alexandra R. L. Kushnir, Patrick Baud, Guanglei Zhou, Michael J. Heap, Tao XuAbstract:Knowledge of the Strength and elastic modulus of a reservoir Rock is important for the optimisation of a particular geothermal resource. The reservoir Rock for many geothermal projects in the Upper Rhine Graben, such as those at Soultz-sous-Forets and Rittershoffen (both France), is porphyritic granite. High fracture densities (up to ~ 30 fractures/m) in this reservoir Rock require that we consider the Strength and elastic modulus of the Rock Mass, rather than the intact Rock. Here we use uniaxial and triaxial deformation experiments performed on intact Rock coupled with Geological Strength Index assessments—using the wealth of information from core and borehole analyses—to provide Rock Mass Strength and elastic modulus estimates for the granite reservoir at Soultz-sous-Forets (from a depth of 1400 to 2200 m) using the generalised Hoek–Brown failure criterion. The average uniaxial compressive Strength and elastic modulus of the intact granite are 140 MPa (this study) and 40 GPa (data from this study and the literature), respectively. The modelled Strength of the intact granite is 360 MPa at a depth of 1400 m and increases to 455 MPa at 2200 m (using our estimate for the empirical m i term of 30, determined using triaxial and tensile Strength measurements on the intact granite). Strength of the Rock Mass varies in accordance with the fracture density and the extent and nature of the fracture infill, reaching lows of ~ 40–50 MPa (in, for example, the densely fractured zones in EPS-1 at depths of ~ 1650 and ~ 2160 m, respectively) and highs of above 400 MPa (in, for example, the largely unfractured zone at a depth of ~ 1940–2040 m). Variations in Rock Mass elastic modulus are qualitatively similar (values vary from 1 to 2 GPa up to the elastic modulus of the intact Rock, 40 GPa). Our study highlights that macrofractures and joints reduce Rock Mass Strength and should be considered when assessing the Rock Mass for well stability and Rock Mass deformation due to stress redistribution in the reservoir. We present a case study to demonstrate how a simple and cost-effective engineering method can be used to provide an indication of the in situ Strength and elastic modulus of reservoir Rock Masses, important for a wide range of modelling and stimulation strategies. We recommend that the effect of macrofractures on Rock Mass Strength and stiffness be validated for incorporation into geomechanical characterisation for geothermal reservoirs worldwide.
