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Dr. Gabriel Walton
Department of Geology and Geological Engineering, Colorado School of Mines, Golden, Colorado, USA

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0 Remote Sensing
0 Rock Mechanics
0 Geological engineering
0 numerical modelling
0 Rockmass characterization

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Rock Mechanics
numerical modelling

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Original paper
Published: 10 August 2021 in Rock Mechanics and Rock Engineering
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Brittleness is an important property of rocks in the context of engineering applications, as it often determines how severe the practical consequences of rock yield will be. Many authors have proposed various brittleness indices intended to allow for relative categorization of brittleness, but many are relatively simplified and/or only applicable for certain categories of rock. This study provides a new perspective on rock brittleness through study of the confining stress at the brittle–ductile transition. Based on previous findings regarding the brittle–ductile transition, an equation to predict this confining stress is derived, and three key material properties associated with material brittleness are identified. Considering these properties, existing assumptions regarding material brittleness as applied in the rock mechanics literature are identified and discussed. A preliminary analysis of data from the literature regarding the influences of fluid saturation and true triaxial loading conditions is presented.

ACS Style

G. Walton. A New Perspective on the Brittle–Ductile Transition of Rocks. Rock Mechanics and Rock Engineering 2021, 1 -14.

AMA Style

G. Walton. A New Perspective on the Brittle–Ductile Transition of Rocks. Rock Mechanics and Rock Engineering. 2021; ():1-14.

Chicago/Turabian Style

G. Walton. 2021. "A New Perspective on the Brittle–Ductile Transition of Rocks." Rock Mechanics and Rock Engineering , no. : 1-14.

Journal article
Published: 14 July 2021 in Sustainability
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The ability to predict the mechanical behavior of brittle rocks using bonded block models (BBM) depends on the accuracy of the geometrical representation of the grain-structure and the applied micro-properties. This paper evaluates the capabilities of BBMs for predictive purposes using an approach that employs published micro-properties in combination with a Voronoi BBM that properly approximates the real rock grain-structure. The Wausau granite, with Unconfined Compressive Strength (UCS) of 226 MPa and average grain diameter of 2 mm, is used to evaluate the effectiveness of the predictive approach. Four published sets of micro-properties calibrated for granites with similar mineralogy to the Wausau granite are used for the assessment. The effect of grain-structure representation in Voronoi BBMs is analyzed, considering grain shape, grain size and mineral arrangement. A unique contribution of this work is the explicit consideration of the effect of stochastic grain-structure generation on the obtained results. The study results show that the macro-properties of a rock can be closely replicated using the proposed approach. When using this approach, the micro-properties have a greater impact on the realism of the predictions than the specific grain-structure representation. The grain shape and grain size representations have a minor effect on the predictions for cases that do not deviate substantially from the real average grain geometry. However, the stochastic effect introduced by the use of randomly-generated Voronoi grain-structures can be significant, and this effect should be considered in future studies.

ACS Style

Carlos Contreras Inga; Gabriel Walton; Elizabeth Holley. Statistical Assessment of the Effects of Grain-Structure Representation and Micro-Properties on the Behavior of Bonded Block Models for Brittle Rock Damage Prediction. Sustainability 2021, 13, 7889 .

AMA Style

Carlos Contreras Inga, Gabriel Walton, Elizabeth Holley. Statistical Assessment of the Effects of Grain-Structure Representation and Micro-Properties on the Behavior of Bonded Block Models for Brittle Rock Damage Prediction. Sustainability. 2021; 13 (14):7889.

Chicago/Turabian Style

Carlos Contreras Inga; Gabriel Walton; Elizabeth Holley. 2021. "Statistical Assessment of the Effects of Grain-Structure Representation and Micro-Properties on the Behavior of Bonded Block Models for Brittle Rock Damage Prediction." Sustainability 13, no. 14: 7889.

Journal article
Published: 16 April 2021 in ISPRS Journal of Photogrammetry and Remote Sensing
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Photogrammetry is increasingly being used to characterize rock slope hazards in mountainous environments. With growth in the amount of point cloud data being collected, there is a need for algorithmic and rapid point cloud interpretation methods to prepare the data for engineering analysis. However, there is a lack of semantic segmentation literature focused on geological datasets and the potential challenges they pose in a practical setting, such as non-ideal data collection parameters, variable lighting conditions, and label noise. This study presents smartphone and UAV photogrammetry datasets including multiple slope morphologies and lighting conditions, manually labels them to create a training database, and classifies points into five geologically relevant categories using Random Forest. Datasets were collected at multiple times of day and seasons to include varying proportions of shadowed areas, examples of clear and overcast skies, and snow. We compared 12 different point cloud feature sets from previous studies, including combinations of geometric, slope, absolute color, and texture features. In addition, we propose multi-scale color standard deviation and the Grey-Level Co-occurrence Matrix as potentially useful descriptors of texture. Accuracy results generally indicate that feature sets containing absolute color features are highly sensitive to changes in lighting conditions and they are not able to discern between various geological materials (soil, talus, rock). In contrast, our novel feature sets with only geometry, slope, and texture were significantly less influenced by lighting and were on average the highest overall accuracy of any feature set tested, with an average overall accuracy of around 80%.

ACS Style

Luke Weidner; Gabriel Walton; Ashton Krajnovich. Classifying rock slope materials in photogrammetric point clouds using robust color and geometric features. ISPRS Journal of Photogrammetry and Remote Sensing 2021, 176, 15 -29.

AMA Style

Luke Weidner, Gabriel Walton, Ashton Krajnovich. Classifying rock slope materials in photogrammetric point clouds using robust color and geometric features. ISPRS Journal of Photogrammetry and Remote Sensing. 2021; 176 ():15-29.

Chicago/Turabian Style

Luke Weidner; Gabriel Walton; Ashton Krajnovich. 2021. "Classifying rock slope materials in photogrammetric point clouds using robust color and geometric features." ISPRS Journal of Photogrammetry and Remote Sensing 176, no. : 15-29.

Journal article
Published: 12 April 2021 in Remote Sensing
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While terrestrial laser scanning and photogrammetry provide high quality point cloud data that can be used for rock slope monitoring, their increased use has overwhelmed current data analysis methodologies. Accordingly, point cloud processing workflows have previously been developed to automate many processes, including point cloud alignment, generation of change maps and clustering. However, for more specialized rock slope analyses (e.g., generating a rockfall database), the creation of more specialized processing routines and algorithms is necessary. More specialized algorithms include the reconstruction of rockfall volumes from clusters and points and automatic classification of those volumes are both processing steps required to automate the generation of a rockfall database. We propose a workflow that can automate all steps of the point cloud processing workflow. In this study, we detail adaptions to commonly used algorithms for rockfall monitoring use cases, such as Multiscale Model to Model Cloud Comparison (M3C2). This workflow details the entire processing pipeline for rockfall database generation using terrestrial laser scanning.

ACS Style

Heather Schovanec; Gabriel Walton; Ryan Kromer; Adam Malsam. Development of Improved Semi-Automated Processing Algorithms for the Creation of Rockfall Databases. Remote Sensing 2021, 13, 1479 .

AMA Style

Heather Schovanec, Gabriel Walton, Ryan Kromer, Adam Malsam. Development of Improved Semi-Automated Processing Algorithms for the Creation of Rockfall Databases. Remote Sensing. 2021; 13 (8):1479.

Chicago/Turabian Style

Heather Schovanec; Gabriel Walton; Ryan Kromer; Adam Malsam. 2021. "Development of Improved Semi-Automated Processing Algorithms for the Creation of Rockfall Databases." Remote Sensing 13, no. 8: 1479.

Journal article
Published: 27 February 2021 in Journal of Rock Mechanics and Geotechnical Engineering
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The residual strength of rocks and rock masses is an important parameter to be constrained for analysis and design purposes in many rock engineering applications. A residual strength envelope in principal stress space is typically developed using residual strength data obtained from compression tests on many different specimens of the same rock type. In this study, we examined the potential for use of the continuous-failure-state testing concept as a means to constrain the residual strength envelope using a limited number of specimens. Specifically, cylindrical specimens of three rock types (granodiorite, diabase, and Stanstead granite) were unloaded at the residual state such that a full residual strength envelope for each individual specimen was obtained. Using a residual strength model that introduces a single new strength parameter (the residual strength index, or RSI), the results of the continuous-failure-state unloading tests were compared to conventionally obtained residual strength envelopes. Overall, the continuous-failure-state residual strength data were found to be consistent with the conventional residual strength data. However, it was identified that the primary factor limiting an accurate characterization of the residual strength for a given rock type is not the amount of data for a given specimen, but the variety of specimens available to characterize the inherent variability of the rock unit of interest. Accordingly, the use of continuous-failure-state testing for estimation of the residual strength of a rock unit is only recommended when the number of specimens available for testing is very limited (i.e. < 5).

ACS Style

Gabriel Walton; Steven Gaines; Leandro R. Alejano. Validity of continuous-failure-state unloading triaxial tests as a means to estimate the residual strength of rocks. Journal of Rock Mechanics and Geotechnical Engineering 2021, 1 .

AMA Style

Gabriel Walton, Steven Gaines, Leandro R. Alejano. Validity of continuous-failure-state unloading triaxial tests as a means to estimate the residual strength of rocks. Journal of Rock Mechanics and Geotechnical Engineering. 2021; ():1.

Chicago/Turabian Style

Gabriel Walton; Steven Gaines; Leandro R. Alejano. 2021. "Validity of continuous-failure-state unloading triaxial tests as a means to estimate the residual strength of rocks." Journal of Rock Mechanics and Geotechnical Engineering , no. : 1.

Journal article
Published: 13 August 2019 in Remote Sensing
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An automated, fixed-location, time lapse camera system was developed as an alternative to monitoring geological processes with lidar or ground-based interferometric synthetic-aperture radar (GB-InSAR). The camera system was designed to detect fragmental rockfalls and pre-failure deformation at rock slopes. It was implemented at a site along interstate I70 near Idaho Springs, Colorado. The camera system consists of five digital single-lens reflex (DSLR) cameras which collect photographs of the rock slope daily and automatically upload them to a server for processing. Structure from motion (SfM) photogrammetry workflows were optimized to be used without ground control. An automated change detection pipeline registers the point clouds with scale adjustment and filters vegetation. The results show that if a fixed pre-calibration of internal camera parameters is used, an accuracy close to that obtained using ground control points can be achieved. Over the study period between March 19, 2018 and June 24, 2019, a level of detection between 0.02 to 0.03 m was consistently achieved, and over 50 rockfalls between 0.003 to 0.1 m3 were detected at the study site. The design of the system is fit for purpose in terms of its ground resolution size and accuracy and can be adapted to monitor a wide range of geological and geomorphic processes at a variety of time scales.

ACS Style

Ryan Kromer; Gabe Walton; Brian Gray; Matt Lato; Robert Group. Development and Optimization of an Automated Fixed-Location Time Lapse Photogrammetric Rock Slope Monitoring System. Remote Sensing 2019, 11, 1890 .

AMA Style

Ryan Kromer, Gabe Walton, Brian Gray, Matt Lato, Robert Group. Development and Optimization of an Automated Fixed-Location Time Lapse Photogrammetric Rock Slope Monitoring System. Remote Sensing. 2019; 11 (16):1890.

Chicago/Turabian Style

Ryan Kromer; Gabe Walton; Brian Gray; Matt Lato; Robert Group. 2019. "Development and Optimization of an Automated Fixed-Location Time Lapse Photogrammetric Rock Slope Monitoring System." Remote Sensing 11, no. 16: 1890.

Technical note
Published: 06 June 2019 in Rock Mechanics and Rock Engineering
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ACS Style

G. Walton; D. Labrie; L. R. Alejano. On the Residual Strength of Rocks and Rockmasses. Rock Mechanics and Rock Engineering 2019, 52, 4821 -4833.

AMA Style

G. Walton, D. Labrie, L. R. Alejano. On the Residual Strength of Rocks and Rockmasses. Rock Mechanics and Rock Engineering. 2019; 52 (11):4821-4833.

Chicago/Turabian Style

G. Walton; D. Labrie; L. R. Alejano. 2019. "On the Residual Strength of Rocks and Rockmasses." Rock Mechanics and Rock Engineering 52, no. 11: 4821-4833.

Journal article
Published: 01 May 2019 in Environmental and Engineering Geoscience
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Terrestrial laser scanning (TLS) is a surveying technology that has seen increasing use in the field of geosciences in recent years. One potential application for this technology is to aid in quantitative stratigraphy. Given a point cloud containing multiple lithologies, the points associated with a specific lithology can be analyzed to quantify the geometric characteristics of that lithology, such as apparent dip, thickness, and spacing. In this study, a semi-automated work flow to perform such a characterization is presented and applied to a case study from an oil sands pit mine in the Athabasca region of Alberta, Canada. The results obtained using data collected with mobile and static TLS systems are compared to evaluate the effects of the various measurements and resolutions on the resulting stratigraphic statistics. In addition, mobile data collected for a small portion of the pit that was actively being mined are compared over time to evaluate changes in sedimentary layering in the direction perpendicular to the pit face. This component of the study highlights the impact of data quality on the resulting interpretations and represents a potential methodology for enhancing three-dimensional quantitative spatial modeling in a sedimentary environment.

ACS Style

Gabriel Walton; Georgia Fotopoulos; Robert Radovanovic. Extraction and Comparison of Spatial Statistics For Geometric Parameters of Sedimentary Layers from Static and Mobile Terrestrial Laser Scanning Data. Environmental and Engineering Geoscience 2019, 25, 155 -168.

AMA Style

Gabriel Walton, Georgia Fotopoulos, Robert Radovanovic. Extraction and Comparison of Spatial Statistics For Geometric Parameters of Sedimentary Layers from Static and Mobile Terrestrial Laser Scanning Data. Environmental and Engineering Geoscience. 2019; 25 (2):155-168.

Chicago/Turabian Style

Gabriel Walton; Georgia Fotopoulos; Robert Radovanovic. 2019. "Extraction and Comparison of Spatial Statistics For Geometric Parameters of Sedimentary Layers from Static and Mobile Terrestrial Laser Scanning Data." Environmental and Engineering Geoscience 25, no. 2: 155-168.

Journal article
Published: 23 November 2018 in Tunnelling and Underground Space Technology
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Recent studies on the behaviour of brittle rock under high stress around excavations have found that the use of a cohesion-weakening-friction-strengthening (CWFS) strength criterion in continuum models has provided excellent agreement with observations made in-situ, including fracture zone size, fracture zone shape, and ground displacement magnitudes. Despite continued success in the application of this strength model for brittle rock, the lack of rigorously established guidelines for CWFS model input parameter selection have limited the use of this approach. In this study, a review of published case studies using the CWFS strength models is provided, and parametric relationships are examined based on the most reliable data sets. Each model parameter is considered individually, and guidelines for parameter selection are provided. In addition, the process of numerical back analysis using the CWFS is discussed and a proposed back analysis methodology is outlined. The use of these guidelines, along with the suggested back analysis approach, will allow for an easier and more effective implementation of the CWFS strength model for numerical modelling of future case studies on brittle rock damage around highly stressed excavations.

ACS Style

G. Walton. Initial guidelines for the selection of input parameters for cohesion-weakening-friction-strengthening (CWFS) analysis of excavations in brittle rock. Tunnelling and Underground Space Technology 2018, 84, 189 -200.

AMA Style

G. Walton. Initial guidelines for the selection of input parameters for cohesion-weakening-friction-strengthening (CWFS) analysis of excavations in brittle rock. Tunnelling and Underground Space Technology. 2018; 84 ():189-200.

Chicago/Turabian Style

G. Walton. 2018. "Initial guidelines for the selection of input parameters for cohesion-weakening-friction-strengthening (CWFS) analysis of excavations in brittle rock." Tunnelling and Underground Space Technology 84, no. : 189-200.

Journal article
Published: 06 October 2018 in Tunnelling and Underground Space Technology
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When constructing an excavation, the segmental lining installed in an anisotropic rock mass is susceptible to asymmetrical pressure and substantial local instabilities. To promote liner stability in such cases, a support system that combines a segmental lining with a highly deformable expanded clay and rock bolts is proposed. A series of physical model tests were performed to study the effect of this support system. In the tests, different dip angles of the primary rock mass jointing, different thicknesses of the expanded clay and different lengths and spacings of rock bolts were considered. Variations in the internal forces and deformation of the segmental lining were recorded in each case. The distribution of the internal forces and deformation of the segmental lining were anisotropic due to the rock mass anisotropy; the maximum positive bending moment and positive deformation on the liner mainly developed in the direction normal to the stratification. By using a sufficiently thick deformable clay layer, the anisotropy of the load transferred to the segmental liner can be minimized. By adding rock bolts, the combined support system can take full advantage of the reinforcement effect of the rock bolts and the yielding effect of the deformable clay layer, and the effect of the rock bolts plus the yielding layer is greater than the sum of the two individual effects. Such a system can change the internal force and deformation distribution of the segmental lining to improve liner stability.

ACS Style

Xiongyu Hu; Yong Fang; Gabriel Walton; Chuan He. Analysis of the behaviour of a novel support system in an anisotropically jointed rock mass. Tunnelling and Underground Space Technology 2018, 83, 113 -134.

AMA Style

Xiongyu Hu, Yong Fang, Gabriel Walton, Chuan He. Analysis of the behaviour of a novel support system in an anisotropically jointed rock mass. Tunnelling and Underground Space Technology. 2018; 83 ():113-134.

Chicago/Turabian Style

Xiongyu Hu; Yong Fang; Gabriel Walton; Chuan He. 2018. "Analysis of the behaviour of a novel support system in an anisotropically jointed rock mass." Tunnelling and Underground Space Technology 83, no. : 113-134.

Journal article
Published: 01 May 2018 in International Journal of Rock Mechanics and Mining Sciences
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ACS Style

Gabriel Walton; Mark S. Diederichs; Klaus Weinhardt; Dani Delaloye; Matthew J. Lato; Allan Punkkinen. Change detection in drill and blast tunnels from point cloud data. International Journal of Rock Mechanics and Mining Sciences 2018, 105, 172 -181.

AMA Style

Gabriel Walton, Mark S. Diederichs, Klaus Weinhardt, Dani Delaloye, Matthew J. Lato, Allan Punkkinen. Change detection in drill and blast tunnels from point cloud data. International Journal of Rock Mechanics and Mining Sciences. 2018; 105 ():172-181.

Chicago/Turabian Style

Gabriel Walton; Mark S. Diederichs; Klaus Weinhardt; Dani Delaloye; Matthew J. Lato; Allan Punkkinen. 2018. "Change detection in drill and blast tunnels from point cloud data." International Journal of Rock Mechanics and Mining Sciences 105, no. : 172-181.

Journal article
Published: 13 April 2018 in International Journal of Rock Mechanics and Mining Sciences
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During construction of a deep shaft at Hecla's Lucky Friday Mine, excessive anisotropic ground deformation led to significant damage to the shaft liner. This necessitated a major design change during construction, with the excavated shape of the shaft being changed from a circular to an approximately elliptical geometry. This study utilizes extensometer data collected during construction as well as a three-dimensional finite-difference model of stress redistribution around the shaft and a calibrated two-dimensional discontinuum numerical model to develop an understanding of the factors affecting the relative stability of both shaft geometries. Although the focus of the work is the deformation behavior of the foliated rock surrounding the shaft, the role of liner installation in suppressing ground displacements is also considered. The change in shaft geometry was found to be highly effective in improving stability of the shaft, with the maximum time-dependent displacement around the shaft decreasing by approximately an order of magnitude. Additionally, finite-difference models confirmed that increased stress concentrations around the shaft caused by adjacent level developments played a significant role in exacerbating ground deformation in the circular portion of the shaft.

ACS Style

G. Walton; E. Kim; S. Sinha; G. Sturgis; D. Berberick. Investigation of shaft stability and anisotropic deformation in a deep shaft in Idaho, United States. International Journal of Rock Mechanics and Mining Sciences 2018, 105, 160 -171.

AMA Style

G. Walton, E. Kim, S. Sinha, G. Sturgis, D. Berberick. Investigation of shaft stability and anisotropic deformation in a deep shaft in Idaho, United States. International Journal of Rock Mechanics and Mining Sciences. 2018; 105 ():160-171.

Chicago/Turabian Style

G. Walton; E. Kim; S. Sinha; G. Sturgis; D. Berberick. 2018. "Investigation of shaft stability and anisotropic deformation in a deep shaft in Idaho, United States." International Journal of Rock Mechanics and Mining Sciences 105, no. : 160-171.

Original paper
Published: 30 September 2017 in Geotechnical and Geological Engineering
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Scale effects refer to changes in mechanical behaviour associated with the volume of material being loaded or deformed. Scale effects in rocks and rockmasses are particularly complex, as an increased volume of interest changes not only the measured behaviour of intact rock, but also results in an increased sampling of natural fractures, which can often significantly influence rockmass mechanical behaviour. To isolate one component of these effects, laboratory tests performed using different size specimens can be used (scale effects in the absence of jointing). Previous studies on scale effects based on laboratory testing have tended to focus on changes in stiffness and peak strength, particularly under unconfined conditions. In this study, data are examined from specimens tested in uniaxial and triaxial compression considering not only stiffness and peak strength, but also strength evolution and post-peak dilatancy evolution. The crack initiation and crack damage stresses are found to be scale independent, whereas the post-yield rate of cohesion loss appears to change as a function of specimen size. Trends in the dilation angle are shown to be relatively scale independent, which is consistent with prior studies that found laboratory-based dilation angle models could be used to accurately replicate data collected from sparsely fractured in situ rockmasses.

ACS Style

G. Walton. Scale Effects Observed in Compression Testing of Stanstead Granite Including Post-peak Strength and Dilatancy. Geotechnical and Geological Engineering 2017, 1 .

AMA Style

G. Walton. Scale Effects Observed in Compression Testing of Stanstead Granite Including Post-peak Strength and Dilatancy. Geotechnical and Geological Engineering. 2017; ():1.

Chicago/Turabian Style

G. Walton. 2017. "Scale Effects Observed in Compression Testing of Stanstead Granite Including Post-peak Strength and Dilatancy." Geotechnical and Geological Engineering , no. : 1.

Original paper
Published: 04 March 2017 in Rock Mechanics and Rock Engineering
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An extensive uniaxial and triaxial compression testing programme was performed on Indiana Limestone to assess its behaviour across the brittle–ductile transition. Particular attention has been paid to the post-yield evolution of strength and dilatancy. Specimens tested at σ3 = 30 MPa displayed a fully ductile failure mechanism, whereas specimens tested at σ3 = 15 MPa and σ3 = 20 MPa displayed transitional mechanisms, which were neither fully brittle nor fully ductile. Based on an examination of failure localization and dilatancy characteristics, the stress at which crack volumetric strain begins to increase was found to be an indicator of individual specimen ductility. In contrast to less porous rocks, the reversal of total volumetric strain did not coincide with the onset of axial strain nonlinearity under unconfined conditions. With respect to post-yield strength, a major change in the rate of friction mobilization relative to plastic shear strain was observed across the brittle–ductile transition. The dilatancy of the specimens was also found to undergo a major change, with the plastic shear strains to mobilization of peak dilatancy in the ductile regime being approximately one order of magnitude higher than in the brittle regime.

ACS Style

G. Walton; Ahmadreza Hedayat; Eunhye Kim; D. Labrie. Post-yield Strength and Dilatancy Evolution Across the Brittle–Ductile Transition in Indiana Limestone. Rock Mechanics and Rock Engineering 2017, 50, 1691 -1710.

AMA Style

G. Walton, Ahmadreza Hedayat, Eunhye Kim, D. Labrie. Post-yield Strength and Dilatancy Evolution Across the Brittle–Ductile Transition in Indiana Limestone. Rock Mechanics and Rock Engineering. 2017; 50 (7):1691-1710.

Chicago/Turabian Style

G. Walton; Ahmadreza Hedayat; Eunhye Kim; D. Labrie. 2017. "Post-yield Strength and Dilatancy Evolution Across the Brittle–Ductile Transition in Indiana Limestone." Rock Mechanics and Rock Engineering 50, no. 7: 1691-1710.

Journal article
Published: 01 October 2015 in Geomechanics and Tunnelling
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Based on recent advances in modelling the post-yield behaviour of brittle rock, the authors have developed a calibrated inelastic model of the 7,910 level (2.4 km depth) at the Creighton Mine in Sudbury, Ontario, Canada using data collected from the monitoring of pillar dilatancy. While this calibrated model represents a state-of-the-art continuum approach for capturing the progressive development of yield and stresses in mine pillars, alternative state-of-practice approaches (elastic and perfectly plastic material models, for example) represent potentially acceptable options for practical application.The purpose of this study is to examine the influence of constitutive model choice on stress paths throughout the pillar system at the mining level of interest. The strengths and limitations of various material models are compared and contrasted. Elastic models are shown to adequately represent the larger scale pillar system behaviour from a stress transfer perspective, whereas the state-of-art brittle modelling approach is shown to be ideal for understanding specific pillar-scale stresses and yield.

ACS Style

Gabriel Walton; Mark Diederichs; Allan Punkkinen. The influence of constitutive model selection on predicted stresses and yield in deep mine pillars - A case study at the Creighton mine, Sudbury, Canada. Geomechanics and Tunnelling 2015, 8, 441 -449.

AMA Style

Gabriel Walton, Mark Diederichs, Allan Punkkinen. The influence of constitutive model selection on predicted stresses and yield in deep mine pillars - A case study at the Creighton mine, Sudbury, Canada. Geomechanics and Tunnelling. 2015; 8 (5):441-449.

Chicago/Turabian Style

Gabriel Walton; Mark Diederichs; Allan Punkkinen. 2015. "The influence of constitutive model selection on predicted stresses and yield in deep mine pillars - A case study at the Creighton mine, Sudbury, Canada." Geomechanics and Tunnelling 8, no. 5: 441-449.

Journal article
Published: 01 September 2015 in Engineering Geology
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ACS Style

G. Walton; M. Lato; H. Anschütz; Matthew Perras; M.S. Diederichs. Non-invasive detection of fractures, fracture zones, and rock damage in a hard rock excavation — Experience from the Äspö Hard Rock Laboratory in Sweden. Engineering Geology 2015, 196, 210 -221.

AMA Style

G. Walton, M. Lato, H. Anschütz, Matthew Perras, M.S. Diederichs. Non-invasive detection of fractures, fracture zones, and rock damage in a hard rock excavation — Experience from the Äspö Hard Rock Laboratory in Sweden. Engineering Geology. 2015; 196 ():210-221.

Chicago/Turabian Style

G. Walton; M. Lato; H. Anschütz; Matthew Perras; M.S. Diederichs. 2015. "Non-invasive detection of fractures, fracture zones, and rock damage in a hard rock excavation — Experience from the Äspö Hard Rock Laboratory in Sweden." Engineering Geology 196, no. : 210-221.

Journal article
Published: 01 December 2014 in Journal of Rock Mechanics and Geotechnical Engineering
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With respect to constitutive models for continuum modeling applications, the post-yield domain remains the area of greatest uncertainty. Recent studies based on laboratory testing have led to the development of a number of models for brittle rock dilation, which account for both the plastic shear strain and confining stress dependencies of this phenomenon. Although these models are useful in providing an improved understanding of how dilatancy evolves during a compression test, there has been relatively little work performed examining their validity for modeling brittle rock yield in situ. In this study, different constitutive models for rock dilation are reviewed and then tested, in the context of a number of case studies, using a continuum finite-difference approach (FLAC). The uncertainty associated with the modeling of brittle fracture localization is addressed, and the overall ability of mobilized dilation models to replicate in situ deformation measurements and yield patterns is evaluated

ACS Style

G. Walton; M.S. Diederichs; Leandro R. Alejano; Javier Arzúa. Verification of a laboratory-based dilation model for in situ conditions using continuum models. Journal of Rock Mechanics and Geotechnical Engineering 2014, 6, 522 -534.

AMA Style

G. Walton, M.S. Diederichs, Leandro R. Alejano, Javier Arzúa. Verification of a laboratory-based dilation model for in situ conditions using continuum models. Journal of Rock Mechanics and Geotechnical Engineering. 2014; 6 (6):522-534.

Chicago/Turabian Style

G. Walton; M.S. Diederichs; Leandro R. Alejano; Javier Arzúa. 2014. "Verification of a laboratory-based dilation model for in situ conditions using continuum models." Journal of Rock Mechanics and Geotechnical Engineering 6, no. 6: 522-534.

Journal article
Published: 01 July 2014 in Tunnelling and Underground Space Technology
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ACS Style

Gabriel Walton; Danielle Delaloye; Mark S. Diederichs. Development of an elliptical fitting algorithm to improve change detection capabilities with applications for deformation monitoring in circular tunnels and shafts. Tunnelling and Underground Space Technology 2014, 43, 336 -349.

AMA Style

Gabriel Walton, Danielle Delaloye, Mark S. Diederichs. Development of an elliptical fitting algorithm to improve change detection capabilities with applications for deformation monitoring in circular tunnels and shafts. Tunnelling and Underground Space Technology. 2014; 43 ():336-349.

Chicago/Turabian Style

Gabriel Walton; Danielle Delaloye; Mark S. Diederichs. 2014. "Development of an elliptical fitting algorithm to improve change detection capabilities with applications for deformation monitoring in circular tunnels and shafts." Tunnelling and Underground Space Technology 43, no. : 336-349.