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| 1 | Characterizing the influence of stress-induced microcracks on the laboratory strength and fracture development in brittle rocks using a finite-discrete element method-micro discrete fracture network FDEM-μDFN approach显示文摘Heterogeneity is an inherent component of rock and may be present in different forms including mineral heterogeneity,geometrical heterogeneity,weak grain boundaries and micro-defects.Microcracks are usually observed in crystalline rocks in two forms:natural and stress-induced;the amount of stressinduced microcracking increases with depth and in-situ stress.Laboratory results indicate that the physical properties of rocks such as strength,deformability,P-wave velocity and permeability are influenced by increase in miciocrack intensity.In this study,the finite-discrete element method(FDEM)is used to model microcrack heterogeneity by introducing into a model sample sets of microcracks using the proposed micro discrete fracture network(μDFN) approach.The characteristics of the microcracks required to create μDFN models are obtained through image analyses of thin sections of Lac du Bonnet granite adopted from published literature.A suite of two-dimensional laboratory tests including uniaxial,triaxial compression and Brazilian tests is simulated and the results are compared with laboratory data.The FDEM-μDFN models indicate that micro-heterogeneity has a profound influence on both the mechanical behavior and resultant fracture pattern.An increase in the microcrack intensity leads to a reduction in the strength of the sample and changes the character of the rock strength envelope.Spalling and axial splitting dominate the failure mode at low confinement while shear failure is the dominant failure mode at high confinement.Numerical results from simulated compression tests show that microcracking reduces the cohesive component of strength alone,and the frictional strength component remains unaffected.Results from simulated Brazilian tests show that the tensile strength is influenced by the presence of microcracks,with a reduction in tensile strength as microcrack intensity increases.The importance of microcrack heterogeneity in reproducing a bi-linear or S-shape failure envelope and its effects on the mechanisms leading to spalling damage near an underground opening are also discussed. | Pooya Hamdi Doug Stead Davide Elmo | 2015 | Journal of Rock Mechanics and Geotechnical Engineering2015，7，6： | 6 |
| 2 | Development of a spring analogue approach for the study of pillars and shafts显示文摘In civil and mining operations that involve ground excavation and support, the loads are distributed between the ground and support depending on their relative stiffness. This paper presents the development of conceptual single-degree-of-freedom models, which are used to derive equations for estimating displacements and stresses for ground-support interaction problems encountered in pillars in room-andpillar mining(natural support system), and liners for circular vertical shafts(artificial support systems).For pillar assessment, mine-pillar interaction curves can be constructed using a double spring analogy.Additionally, the effectiveness of different support systems can be evaluated depending on their effect upon the mine-pillar system. For shaft design, an initial estimation of the required lining strength and thickness can be readily made based on a double ring analogue. For both problems, the results from the proposed approach compare well with those obtained by finite element numerical simulations. | Amichai Mitelman Davide Elmo Doug Stead | 2018 | International Journal of Mining Science and Technology2018，28，2： | 2 |
| 3 | The role of tectonic damage and brittle rock fracture in the development of large rock slope failures显示文摘 | Brideau Marc-Andr6 Yah Ming Stead Doug | 2009 | Geomorphology2009，103，1： | 1 |
| 4 | The role of tectonic damage and brittle rock fracture in the development of large rock slope failures显示文摘 | Marc-André Brideau Ming Yan Doug Stead | 2008 | Geomorphology2008，，1： | 1 |
| 5 | Numerical mod- elfing of the effects of weak immediate roof lithology on coal mine roadway stability 显示文摘 | John Cegsan Fucliang Gao Doug Stead et at | 2012 | International Journal of Coal Geolo-gy2012，9091，1： | 1 |
| 6 | New approaches to quantify progressive damage and associated dynamic rock mass blockiness显示文摘In the past decade, numerical modelling has been increasingly used for simulating the mechanical behaviour of naturally fractured rock masses. In this paper, we introduce new algorithms for spatial and temporal analyses of newly generated fractures and blocks using an integrated discrete fracture network (DFN)-finite-discrete element method (FDEM) (DFN-FDEM) modelling approach. A fracture line calculator and analysis technique (i.e. discrete element method (DEM) fracture analysis, DEMFA) calculates the geometrical aspects of induced fractures using a dilation criterion. The resultant two-dimensional (2D) blocks are then identified and characterised using a graph structure. Block tracking trees allow track of newly generated blocks across timesteps and to analyse progressive breakage of these blocks into smaller blocks. Fracture statistics (number and total length of initial and induced fractures) are then related to the block forming processes to investigate damage evolution. The combination of various proposed methodologies together across various stages of modelling processes provides new insights to investigate the dependency of structure's resistance on the initial fracture configuration. | Ladan Karimi Sharif Davide Elmo Doug Stead | 2023 | Journal of Rock Mechanics and Geotechnical Engineering2023，15，2： | 0 |
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