A clumped particle model for rock

Cho, N.; Martin, C. Derek; Sego, David C.

doi:10.1016/j.ijrmms.2007.02.002

Cited by 866 publications

(359 citation statements)

References 18 publications

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“…For the simulation ξ was selected to be 0.05 and the time step calculated to be 1×10 -7 s. For this study, the combination of loading rate and time step was chosen to ensure minimal dynamic effects with a total of 10,000 calculation steps required to be computed for the specimen to displace 1 mm; as a result, the dynamic effects were minimal [8].…”

Section: Model Input Parametersmentioning

confidence: 99%

“…They are capable of resisting the relative displacement of bonded particles in compression and tension; there is no resistance against shear, bending or twisting actions. An improved bonded contact model was developed by Potyondy and Cundall [7] where particles are connected by a point of glue which is represented by a pair of elastic springs with a constant normal and shear stiffness [8]. This was further developed by the authors into the more complex parallel bond model [7] which has since been used by many researchers [e.g.…”

Section: Introductionmentioning

confidence: 99%

“…This was further developed by the authors into the more complex parallel bond model [7] which has since been used by many researchers [e.g. 8,9].…”

Section: Introductionmentioning

confidence: 99%

“…The bonded contacts in the parallel bond model can be considered as "a set of elastic springs uniformly distributed over the cross section with a constant normal and shear bond stiffness lying on the contact plane and centred at the contact point" [8]. In addition to normal and shear forces, the parallel bond is also able to transmit moments.…”

Section: Introductionmentioning

confidence: 99%

“…Most of the work has covered the behaviour of cementitious materials under quasi-static uni-axial loading, such as rock in 2D [8] and 3D [6,7], and concrete in 2D [18] and 3D [12]. A uni-axial loading test is often used to calibrate models for different materials.…”

Section: Introductionmentioning

confidence: 99%

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A bond model for DEM simulation of cementitious materials and deformable structures

2014

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There is an increasing use of the discrete element method (DEM) to study cemented (e.g. concrete and rocks) and sintered particulate materials. The chief advantage of the DEM over continuum based techniques is that it does not make assumptions about how cracking and fragmentation initiate and propagate, since the DEM system is naturally discontinuous. The ability for the DEM to produce a realistic representation of a cemented granular material depends largely on the implementation of an inter-particle bonded contact model. This paper presents a new bonded contact model based on the Timoshenko beam theory which considers axial, shear and bending behaviour of the bond. The bond model was first verified by simulating both the bending and dynamic response of a simply supported beam. The loading response of a concrete cylinder was then investigated and compared with the Eurocode equation prediction. The results show significant potential for the new model to produce satisfactory predictions for cementitious materials. A unique feature of this model is that it can also be used to accurately represent many deformable structures such as frames and shells, so that both particles and structures or deformable boundaries can be described in the same DEM framework.

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Section: Model Input Parametersmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…This was further developed by the authors into the more complex parallel bond model [7] which has since been used by many researchers [e.g. 8,9].…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A bond model for DEM simulation of cementitious materials and deformable structures

2014

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Evolution of stress‐induced borehole breakout in inherently anisotropic rock: Insights from discrete element modeling

Kang

Kwok

2016

JGR Solid Earth

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The aim of this study is to better understand the mechanisms controlling the initiation, propagation, and ultimate pattern of borehole breakouts in shale formation when drilled parallel with and perpendicular to beddings. A two‐dimensional discrete element model is constructed to explicitly represent the microstructure of inherently anisotropic rocks by inserting a series of individual smooth joints into an assembly of bonded rigid discs. Both isotropic and anisotropic hollow square‐shaped samples are generated to represent the wellbores drilled perpendicular to and parallel with beddings at reduced scale. The isotropic model is validated by comparing the stress distribution around borehole wall and along X axis direction with analytical solutions. Effects of different factors including the particle size distribution, borehole diameter, far‐field stress anisotropy, and rock anisotropy are systematically evaluated on the stress distribution and borehole breakout propagation. Simulation results reveal that wider particle size distribution results in the local stress perturbations which cause localization of cracks. Reduction of borehole diameter significantly alters the crack failure from tensile to shear and raises the critical pressure. Rock anisotropy plays an important role on the stress state around wellbore which lead to the formation of preferred cracks under hydrostatic stress. Far‐field stress anisotropy plays a dominant role in the shape of borehole breakout when drilled perpendicular to beddings while a secondary role when drilled parallel with beddings. Results from this study can provide fundamental insights on the underlying particle‐scale mechanisms for previous findings in laboratory and field on borehole stability in anisotropic rock.

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Discrete element modeling of indentation tests to investigate mechanisms of CO₂‐related chemomechanical rock alteration

2016

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During CO2 injection into geological formations, petrophysical and geomechanical properties of host formations can be altered due to mineral dissolution and precipitation. Field and laboratory results have shown that sandstone and siltstone can be altered by CO2‐water mixtures, but few quantitative studies have been performed to fully investigate underlying mechanisms. Based on the hypothesis that CO2‐water mixtures alter the integrity of rock structure by attacking cements rather than grains, we attempt to explain the degradation of cementation due to long‐term contact with CO2 and water and mechanisms for changes in rock mechanical properties. Many sandstones, including calcite‐cemented quartzitic sandstone, chlorite‐cemented quartzitic sandstone, and hematite‐cemented quartzitic sandstone, contain interparticle cements that are more readily affected by CO2‐water mixtures than grains. A model that couples the discrete element method and the bonded‐particle model is used to perform simulations of indentation tests on synthetic rocks with crystal and random packings. The model is verified against the analytical cavity expansion model and validated against laboratory indentation tests on Entrada sandstone with and without CO2 alteration. Sensitivity analysis is performed for cementation microscopic parameters including stiffness, size, axial, and shear strength. The simulation results indicate that the CO2‐related degradation of mechanical properties in bleached Entrada sandstone can be attributed to the reduction of cement size rather than cement strength. Our study indicates that it is possible to describe the CO2‐related rock alteration through particle‐scale mechanisms.

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A clumped particle model for rock

Cited by 866 publications

References 18 publications

A bond model for DEM simulation of cementitious materials and deformable structures

A bond model for DEM simulation of cementitious materials and deformable structures

Evolution of stress‐induced borehole breakout in inherently anisotropic rock: Insights from discrete element modeling

Discrete element modeling of indentation tests to investigate mechanisms of CO₂‐related chemomechanical rock alteration

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A clumped particle model for rock

Cited by 866 publications

References 18 publications

A bond model for DEM simulation of cementitious materials and deformable structures

A bond model for DEM simulation of cementitious materials and deformable structures

Evolution of stress‐induced borehole breakout in inherently anisotropic rock: Insights from discrete element modeling

Discrete element modeling of indentation tests to investigate mechanisms of CO2‐related chemomechanical rock alteration

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Resources

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Discrete element modeling of indentation tests to investigate mechanisms of CO₂‐related chemomechanical rock alteration