A study on the effects of microparameters on macroproperties for specimens created by bonded particles

Yang, Bowei; Jiao, Yue; Lei, Shuting

doi:10.1108/02644400610680333

Cited by 168 publications

(74 citation statements)

References 62 publications

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“…The results show that E c increases with the increasing of k s /k n at different values of k m /(k n R), and v c decreases with the increasing of k s /k n . The trends are in accord with those in [28,29,34]. With the values of the k s /k n changing from 0.1 to 1.0, Poisson's ratio decreases from 0.45 to 0.…”

Section: Effect Of Bond Stiffness On Macro Parameterssupporting

confidence: 83%

Bonded-Particle Model with Nonlinear Elastic Tensile Stiffness for Rock-Like Materials

Ouyang

Chen

2017

Applied Sciences

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Abstract:The bonded-particle model (BPM) is a very efficient numerical method in dealing with initiation and propagation of cracks in rocks and can model the fracture processes and most of macro parameters of rocks well. However, typical discrete element method (DEM) underestimates the ratio of the uniaxial compressive strength to the tensile strength (UCS/TS). In this paper, a new DEM method with a nonlinear elastic tensile model embedded in BPM is proposed, which is named as nonlinear elastic tensile bonded particle model (NET-BPM). The relationships between micro parameters in NET-BPM and macro parameters of specimens are investigated by simulating uniaxial compression tests and direct tension tests. The results show that both the shape coefficient of the nonlinear elastic model and the bond width coefficient are important in predicting the value of UCS/TS, whose value ranging from 5 to 45 was obtained in our simulations. It is shown that the NET-BPM model is able to reproduce the nonlinear behavior of hard rocks such as Lac du Bonnet (LDB) granite and the quartzite under tension and the ratio of compressive Young's modulus to tensile Young's modulus higher than 1.0. Furthermore, the stress-strain curves in the simulations of LDB granite and the quartzite with NET-BPM model are in good agreement with the experimental results. NET-BPM is proved to be a very suitable method for modelling the deformation and fracture of rock-like materials.

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Section: Effect Of Bond Stiffness On Macro Parameterssupporting

confidence: 83%

Bonded-Particle Model with Nonlinear Elastic Tensile Stiffness for Rock-Like Materials

Ouyang

Chen

2017

Applied Sciences

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“…Contact normal stiffness (k n ) of the disks was set to 5·10 9 N/m, and the contact shear stiffness (k s ) was set to half of the contact normal stiffness because results are not 130 affected significantly for different ratios of k n /k s . A recent paper by Yang et al (2006) also found that k n /k s ratios have little effect on the compressive strength of the material created by bonded particles. Therefore, k n /k s = 2 was assumed in this analysis following a linear contact law.…”

Section: Simulation Of Granular Assemblymentioning

confidence: 96%

DEM analysis of angular ballast breakage under cyclic loading

Hossain

Indraratna

Darve

et al. 2007

Geomechanics and Geoengineering

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Railway ballast particles undergo significant amount of breakage under repeated train load. Breakage of ballast particles, especially highly angular fresh ones, causes an increase in settlement, contributing to track degradation. The quantitative analysis of the influence of breakage on the stress-strain properties of ballast can be performed either experimentally or numerically. Numerical modeling has the advantage of simulating ballast breakage 10 subject to various types of loading and different boundary conditions for a range of material properties. In this paper, ballast breakage under cyclic loading is simulated using a 2D discrete element method (DEM) utilizing the software PFC 2D . A new subroutine is developed and incorporated in the PFC 2D analysis to study ballast breakage and to quantify breakage in relation to particle size distribution. The influence of confining pressure on both breakage and permanent deformation is also studied and compared with laboratory observations. The findings of this paper provide an insight into the true ballast behavior under cyclic loading and are expected to assist railway practitioners in developing suitable design criteria for track stability. 15

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“…In the present work, the micromechanical parameters have been determined using the methodology based on the dimensional analysis proposed by Huang (1999) and used later in other works, cf. (Fakhimi and Villegas 2007;Yang et al 2006;Rojek et al 2011;Labra 2012). Results of numerical simulations of the standard laboratory tests for rocks, the unconfined compressive strength (UCS) test and the Brazilian tensile strength (BTS), will allow us to establish dimensionless relationships between the contact parameters and the mechanical material properties.…”

Section: Determination Of Dem Parametersmentioning

confidence: 99%

Discrete/Finite Element Modelling of Rock Cutting with a TBM Disc Cutter

Labra¹,

Rojek

Oñate

2016

Rock Mech Rock Eng

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This paper presents advanced computer simulation of rock cutting process typical for excavation works in civil engineering. Theoretical formulation of the hybrid discrete/finite element model has been presented. The discrete and finite element methods have been used in different subdomains of a rock sample according to expected material behaviour, the part which is fractured and damaged during cutting is discretized with the discrete elements while the other part is treated as a continuous body and it is modelled using the finite element method. In this way, an optimum model is created, enabling a proper representation of the physical phenomena during cutting and efficient numerical computation. The model has been applied to simulation of the laboratory test of rock cutting with a single TBM (tunnel boring machine) disc cutter. The micromechanical parameters have been determined using the dimensionless relationships between micro-and macroscopic parameters. A number of numerical simulations of the LCM test in the unrelieved and relieved cutting modes have been performed. Numerical results have been compared with available data from in-situ measurements in a real TBM as well as with the theoretical predictions showing quite a good agreement. The numerical model has provided a new insight into the cutting mechanism enabling us to investigate the stress and pressure distribution at the tool-rock interaction. Sensitivity analysis of rock cutting performed for different parameters including disc geometry, cutting velocity, disc penetration and spacing has shown that the presented numerical model is a suitable tool for the design and optimization of rock cutting process.

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A study on the effects of microparameters on macroproperties for specimens created by bonded particles

Cited by 168 publications

References 62 publications

Bonded-Particle Model with Nonlinear Elastic Tensile Stiffness for Rock-Like Materials

Bonded-Particle Model with Nonlinear Elastic Tensile Stiffness for Rock-Like Materials

DEM analysis of angular ballast breakage under cyclic loading

Discrete/Finite Element Modelling of Rock Cutting with a TBM Disc Cutter

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