Relationship between the deformation characteristics and microscopic properties of sandstone explored by the bonded-particle model

Weng, Meng-Chia; Li, Hung Hui

doi:10.1016/j.ijrmms.2012.07.003

Cited by 45 publications

(12 citation statements)

References 39 publications

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“…Similar with the bonded‐particle model, it is difficult to determine the parameters for SJM directly by laboratory tests. Studies have been carried out to provide guidance for the selection of parameters for bonded‐particle model, but a calibration process for SJM is necessary. Comprehensive understanding of the effect of smooth‐joint parameters on the mechanical properties on jointed rock is essential for the selection of microparameters and for the understanding of mechanisms of dominating joints with different properties.…”

Section: Introductionmentioning

confidence: 99%

Parametric study of the smooth‐joint contact model on the mechanical behavior of jointed rock

Kwok

Kang

et al. 2017

Num Anal Meth Geomechanics

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The smooth-joint contact model based on distinct element method has been widely used to represent discontinuity in the simulation of fractured rock mass, but there is rare efficient guidance for the selection of proper parameters of smooth-joint contact model, which is the basement for using this model properly. In this paper, the effect of smooth joint parameters on the macroscopic properties and failure mechanism of jointed rock under triaxial compression test is investigated. The numerical results reveal that the friction coefficient of smooth joint plays a dominant role in controlling mechanical behaviors. The stiffness of smooth joint has a relative small influence on the mechanical behaviors. Poisson ratio decreases with the reduction of normal stiffness but increases with the reduction of shear stiffness. The reduction of smooth joint strength, which is determined by normal strength, cohesion, and friction angle of smooth joint, contributes to the breakage of bonded smooth joint and ultimately decreases the strength of the specimen. We proposed a detailed calibration process for smooth-joint contact model according to the relationship between smooth-joint parameters and mechanical properties. By following this process, the numerical results are validated against corresponding experimental results and good agreement between them can be found in stress-strain curves and failure modes of different joint orientations. Further analyses from the microperspective are performed by looking at transmission of contact force, the nature and distribution of microcracks, and the particle displacement to show the failure process and failure modes.KEYWORDS compression test, distinct element method, failure mode, smooth-joint contact | INTRODUCTIONThe mechanical behavior of jointed rock mass is strongly dependent on the combined behavior of intact rock and joints. According to different criterions, joints can be classified into various types, eg, persistent/nonpersistent joints based on the presence of collinear rock bridges, filled/unfilled joints based on the containing of soft materials such as clays, and rough/smooth joints based on the surface characteristic. In the case of unfilled joints, the roughness and compressive strength of the joint walls are found important, while in the case of filled joints, the physical and mechanical properties of the filling material are of primary concern 1 . Moreover, joint roughness has been recognized to have a significant impact on the shear behavior of joints 2 . In many engineering structures constructed within or upon rock masses, such

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Section: Introductionmentioning

confidence: 99%

Parametric study of the smooth‐joint contact model on the mechanical behavior of jointed rock

Kwok

Kang

et al. 2017

Num Anal Meth Geomechanics

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“…The Distinct Element Method (DEM) proposed by Cundall and Strack has proved to be a very promising tool in granular mechanics . During the last ten years DEM has been improved to investigate the mechanical behavior of bonded granulates . It has been accepted that the key to the application of DEM to bonded granular assemblies is the bond contact model for describing the behavior of bonding.…”

Section: Introductionmentioning

confidence: 99%

“…This is because the microscopic information on bonded sands during loading, especially the evolution of bond degradation, is extremely difficult to obtain in the laboratory, even with current advanced technologies such as X-ray radiography [28], laser-aided tomography [29], X-ray computed tomography [30] and synchrotron microtomography [31].The Distinct Element Method (DEM) proposed by Cundall and Strack [32] has proved to be a very promising tool in granular mechanics [32][33][34][35][36]. During the last ten years DEM has been improved to investigate the mechanical behavior of bonded granulates [26,[37][38][39][40][41][42][43][44][45]. It has been accepted that the key to the application of DEM to bonded granular assemblies is the bond contact model for describing the behavior of bonding.…”

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confidence: 99%

A simple three‐dimensional distinct element modeling of the mechanical behavior of bonded sands

Jiang

Zhang

Thornton

2015

Num Anal Meth Geomechanics

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Summary This paper presents a simple three‐dimensional (3D) Distinct Element Method (DEM) for numerical simulation of the mechanical behavior of bonded sands. First, a series of micro‐mechanical tests on a pair of aluminum rods glued together by cement with different bond sizes were performed to obtain the contact mechanical responses of ideally bonded granular material. Second, a 3D bond contact model, which takes into account the influences of bond sizes, was established by extending the obtained 2D experimental results to 3D case. Then, a DEM incorporating the new contact model was employed to perform a set of drained triaxial compression tests on the DEM bonded specimens with different cement contents under different confining pressures. Finally, the mechanical behavior of the bonded specimens was compared with the available experimental results. The results show that the DEM incorporating the simple 3D bond contact model is able to capture the main mechanical behavior of bonded sands. The bonded specimen with higher cement content under lower confining pressure exhibits more pronounced strain softening and shear dilatancy. The peak and residual strengths, the apparent cohesion and peak/residual friction angles, and the position and slope of the critical state line increase with increase in cement content. Microscopically, bond breakage starts when the system starts to dilate and the maximum rate of bond breakage coincides with the maximum rate of dilation. Bond breakage is primarily due to tension‐shear failure and the percentage of such failures is independent of both confining pressure and cement content. Copyright © 2015 John Wiley & Sons, Ltd.

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“…As can be seen, it includes the micromechanical parameters of the particles and the parallel bond between them. According to the existing literature [31,32] and our calibration process, the macro elastic modulus of the model was controlled by the contact modulus, and Poisson's ratio was affected by the ratio of normal stiffness to shear stiffness. The strength of the model was mainly decided by the tensile and shear strengths of the bond.…”

Section: Calibration Of the Microparametersmentioning

confidence: 99%

Numerical Investigation of Mineral Grain Shape Effects on Strength and Fracture Behaviors of Rock Material

2019

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Rock is an aggregate of mineral grains, and the grain shape has an obvious influence on rock mechanical behaviors. Current research on grain shape mostly focuses on loose granular materials and lacks standardized quantitative methods. Based on the CLUMP method in the two-dimensional particle flow code (PFC 2D ), three different grain groups were generated: strip, triangle, and square. Flatness and roughness were adopted to describe the overall contour and the surface morphology of the mineral grains, respectively. Simulated results showed that the grain shape significantly affected rock porosity and further influenced the peak strength and elastic modulus. The peak strength and elastic modulus of the model with strip-shaped grains were the highest, followed by the models with triangular and square grains. The effects of flatness and roughness on rock peak strength were the opposite, and the peak strength had a significant, positive correlation with cohesion. Tensile cracking was dominant among the generated microcracks, and the percentage of tensile cracking was maximal in the model with square grains. At the postpeak stage, the interlocking between grains was enhanced along with the increased surface roughness, which led to a slower stress drop.

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Relationship between the deformation characteristics and microscopic properties of sandstone explored by the bonded-particle model

Cited by 45 publications

References 39 publications

Parametric study of the smooth‐joint contact model on the mechanical behavior of jointed rock

Parametric study of the smooth‐joint contact model on the mechanical behavior of jointed rock

A simple three‐dimensional distinct element modeling of the mechanical behavior of bonded sands

Numerical Investigation of Mineral Grain Shape Effects on Strength and Fracture Behaviors of Rock Material

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