Discrete element simulation of ballast and gravel under special consideration of grain-shape, grain-size and relative density

Stahl, M.; Konietzky, Heinz

doi:10.1007/s10035-010-0239-y

Cited by 118 publications

(38 citation statements)

References 5 publications

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“…For railway ballast several approaches can be found in the literature, which use rigid clumps of spheres, see e.g. [4, 8, 10, 13, 17], clumps of bonded spheres, see e.g. [9, 14], polyhedra, see e.g.…”

Section: Introductionmentioning

confidence: 99%

Comparison of two different types of railway ballast in compression and direct shear tests: experimental results and DEM model validation

2018

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Railway ballast is an angular and coarse material, which demands careful DEM modelling and validation. Particle shape is often modelled in high accuracy, thus leading to computational expensive DEM models. Whether this effort will increase the DEM model’s overall prediction quality will also vitally depend on the used contact law and the validation process. In general, a DEM model validated using different types of principal experiments can be considered more trustworthy in simulating other load cases. Here, two types of railway ballast are compared and DEM model validation is conducted. Calcite and Kieselkalk are investigated under compression and direct shear test. All experimental data will be made openly accessible to promote further research on this topic. In the experiments, the behaviour of Calcite and Kieselkalk is surprisingly similar in the direct shear test, while clear differences can be seen in the stiffnesses in the compression test. In DEM modelling, simple particle shapes are combined with the Conical Damage Model contact law. For each type of ballast, one set of parameters is found, such that simulation and experimental results are in good accordance. A comparison with the simplified Hertz-Mindlin contact law shows several drawbacks of this model. First, the model cannot be calibrated to meet both compression and shear test results. Second, the similar behaviour in shear testing but differences in compression cannot be reproduced using the Hertz-Mindlin model. For these reasons, the CDM model is considered the better choice for the simulation of railway ballast, if simple particle shapes are used.

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Section: Introductionmentioning

confidence: 99%

Comparison of two different types of railway ballast in compression and direct shear tests: experimental results and DEM model validation

2018

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“…Salot et al [53] and Wang et al [66] demonstrated that the value of the critical state friction angle depends on the particle shape. The influence of the particle shape on the asymptotic behaviour was also emphasized in [17,30,33,38,58]. Luding and Alonso-Marroquín [36] observed that the critical state friction angle was constant for non-adhesive contact behaviour, but showed a pressure dependence for adhesive inter-particle contacts.…”

Section: Introductionmentioning

confidence: 93%

Asymptotic behaviour of granular materials

Maš́ın

2012

Granular Matter

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The concept of the asymptotic behaviour of particulate materials is described, including its enhancement by considering asymptotic states in extension. A 3D discrete element model with elastic spherical particles and the granulometry of a real sand is set up. The numerical sample is stretched from different initial states, and the influence of the strain rate direction on the final state is studied within the stress ratio, void ratio and mean stress space. Asymptotic behaviour is clearly observed, although the grains remain intact (no grain crushing is considered). The extension asymptotic states are observed, and the notion of a normal extension line is introduced. The extension asymptotic states coincide with the peak states observed in the shear tests with constant stress path direction in dense samples.

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“…In one group are what we call the object‐based models , which are those that model porous media as a collection of particles or objects, regardless of how they have been formed [ Torquato , ; Sahimi , , ]. In the earliest approach [ Cundall and Strack , ] particles with relatively simple shapes, such as circles and spheres, were used [ Salot et al , ; Katagiri et al , ; Stahl and Konietzky , ], for which the computations are straightforward, with their flow properties typically computed by the lattice Boltzmann method [ Pan et al , ], their diffusion and electrical conductivity by the random walk method [ Sahimi , ], while the mechanical properties are studied by the discrete‐element method (DEM) [ Cundall and Strack , ]. The DEM is, however, accurate if the granular medium consists of particles that are not too complex.…”

Section: Introductionmentioning

confidence: 99%

Image‐based modeling of granular porous media

Tahmasebi

Sahimi

Andrade

2017

Geophysical Research Letters

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We propose a new method of modeling granular media that utilizes a single two‐ or three‐dimensional image and is formulated based on a Markov process. The process is mapped onto one that minimizes the difference between the image and a stochastic realization of the granular medium and utilizes a novel approach to remove possible unphysical discontinuities in the realization. Quantitative comparison between the morphological properties of the realizations and representative examples indicates excellent agreement.

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Discrete element simulation of ballast and gravel under special consideration of grain-shape, grain-size and relative density

Cited by 118 publications

References 5 publications

Comparison of two different types of railway ballast in compression and direct shear tests: experimental results and DEM model validation

Comparison of two different types of railway ballast in compression and direct shear tests: experimental results and DEM model validation

Asymptotic behaviour of granular materials

Image‐based modeling of granular porous media

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