DEM Simulation of Direct Shear: 2. Grain Boundary and Mineral Grain Strength Component Influence on Shear Rupture

Bewick, Rob; Kaiser, Peter K.; Bawden, W.F.

doi:10.1007/s00603-013-0494-4

Cited by 57 publications

(19 citation statements)

References 8 publications

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“…This mimics the real microstructure of crystalline rocks more closely and allows matching the ratio between unconfined-compressive strength and direct-tension strength more closely, as well [39]. Recently PFC2D GBM studies have been conducted [40][41][42][43], however, while the ratio between direct tensile strength and unconfined compressive strength could be matched by the GBM approach, the Brazilian tensile tests and unconfined compression test results can still not be reproduced with the same model when only one mineral type is considered in the model [43]. Therefore, four different mineral types are explicitly modeled in this study.…”

Section: Pfc2d Grain Based Modeling (Gbm) Of Brittle Failure Of Granitesmentioning

confidence: 98%

A grain based modeling study of mineralogical factors affecting strength, elastic behavior and micro fracture development during compression tests in granites

Hofmann

Babadagli

Yoon

et al. 2015

Engineering Fracture Mechanics

134

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Section: Pfc2d Grain Based Modeling (Gbm) Of Brittle Failure Of Granitesmentioning

confidence: 98%

A grain based modeling study of mineralogical factors affecting strength, elastic behavior and micro fracture development during compression tests in granites

Hofmann

Babadagli

Yoon

et al. 2015

Engineering Fracture Mechanics

134

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“…One merit of the PFC2D grain-based model Journal of Geophysical Research: Solid Earth 10.1002/2016JB013469 is that the model can not only simulate the microcrack initiation and interaction at the grain boundary but also capture the microcracking behavior inside the grains which is associated with intragranular microcracking. This method has been demonstrated to be capable of simulating the failure behavior and microcracking process of crystalline rocks [Bahrani and Kaiser, 2016;Bahrani et al, 2014;Bewick et al, 2014aBewick et al, , 2014bHofmann et al, 2015aHofmann et al, , 2015b.…”

Section: Grain-based Modeling Approach In Pfc2dmentioning

confidence: 99%

Influence of grain size heterogeneity on strength and microcracking behavior of crystalline rocks

2017

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This study numerically investigates the influence of material heterogeneity on the strength and deformation behavior and the associated microcracking process of a felsic crystalline rock using a grain‐based modeling approach in two‐dimensional Particle Flow Code. By using a heterogeneity index defined in this study, the heterogeneity induced by variation of grain size distribution can be explicitly incorporated into the numerical specimen models quantitatively. Under compressive loading, the peak strength and the elastic modulus are found to increase as the numerical model gradually changes from heterogeneous to homogeneous, i.e., a decrease of heterogeneity index. Meanwhile, the number of grain boundary tensile cracks gradually decreases and the number of intragrain cracks increases at the moment of failure. However, the total number of generated microcracks seems not to be significantly influenced by heterogeneity. The orientation of grain boundary microcracks is mainly controlled by the geometry of assembled grain structure of the numerical specimen model, while the orientation of intragrain microcracks is to a large degree influenced by the confinement. In addition, the development of intragrain cracks (both tensile and shear) is much more favored in quartz than in other minerals. Under direct tensile loading, heterogeneity is found to have no significant influence on the simulated stress‐strain responses and rock strength. Only grain boundary tensile cracks are generated when the numerical models are loaded in direct tension, and the position of generated macroscopic fracture developed upon failure of the specimen is largely affected by heterogeneity.

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“…To resolve this issue, Potyondy [34] developed a methodology in PFC2D, where a rock is simulated by deformable and breakable polygonal grains. The results of the calibration of the grain-based model (GBM) to laboratory test results of Äspӧ Diorite, Wombeyan marble, LdB granite, Lodève sandstone have been reported by Potyondy [34], Bahrani et al [35], Bahrani et al [36], and Bewick et al [37,38], respectively. For the GBM with breakable grains, the micro-properties of both grains and grain boundaries must be defined.…”

Section: Calibration Of Pfc Model To Laboratory Properties Of Intact mentioning

confidence: 98%

Distinct element method simulation of an analogue for a highly interlocked, non-persistently jointed rockmass

Bahrani

Kaiser

Valley

2014

International Journal of Rock Mechanics and Mining Sciences

143

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A grain-based distinct element model is used to reproduce the laboratory response of both intact and granulated Wombeyan marble. The term "granulated" refers to a heat treated marble where the cohesion of grain boundaries has been destroyed. The unconfined compressive strength of granulated marble is less than 50% of that of intact marble, while the strength of the granulated marble increases to about 80% of that of the intact marble at higher confining stresses. An iterative calibration approach is developed to match the unconfined and confined strengths of the models to those of intact and granulated marble. The simulation test results of the models of intact and granulated marble including the transition in the failure mode, stress-strain response, and the evolution of inter-and intra-grain micro-cracks with increasing confinement are discussed. The observed rapid strengthening effect, in terms of increasing confinement, is interpreted to be due to the high degree of grain assembly geometric interlock, which arises from the tight fit geometric shape of the grains as well as the roughness of the grain boundaries. It is suggested that the granulated marble can be considered to be an analogue for a highly interlocked, non-persistently jointed rockmass. It is shown that when the generalized Hoek-Brown failure criterion and the Geological Strength Index (GSI) are used to match the strength of the granulated marble at zero confinement, the confined strength of the granulated marble is underestimated by as much as a factor of two. Therefore, the confined strength of a highly interlocked, nonpersistently jointed rockmass, with strong, brittle rock blocks, could be significantly higher than that predicted by commonly adopted empirical approaches. This has practical implications for the design of highly confined pillars and abutments, which is discussed in this paper.

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DEM Simulation of Direct Shear: 2. Grain Boundary and Mineral Grain Strength Component Influence on Shear Rupture

Cited by 57 publications

References 8 publications

A grain based modeling study of mineralogical factors affecting strength, elastic behavior and micro fracture development during compression tests in granites

A grain based modeling study of mineralogical factors affecting strength, elastic behavior and micro fracture development during compression tests in granites

Influence of grain size heterogeneity on strength and microcracking behavior of crystalline rocks

Distinct element method simulation of an analogue for a highly interlocked, non-persistently jointed rockmass

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