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

机译：两种不同类型的铁路道ast在压缩和直接剪切试验中的比较：实验结果和DEM模型验证

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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.
机译：铁路道ast是一种棱角分明的粗糙材料，需要仔细的DEM建模和验证。粒子形状通常以高精度建模，从而导致计算量大的DEM模型。这项工作是否会提高DEM模型的整体预测质量，也将在很大程度上取决于所使用的联系法和验证过程。通常，在模拟其他工况时，可以认为使用不同类型的主要实验验证的DEM模型更值得信赖。在此，比较了两种类型的铁路道ball，并进行了DEM模型验证。方解石和Kieselkalk在压缩和直接剪切试验下进行了研究。所有实验数据将公开提供，以促进对该主题的进一步研究。在实验中，方解石和Kieselkalk的行为在直接剪切试验中出奇地相似，而在压缩试验中的刚度却有明显差异。在DEM建模中，将简单的粒子形状与“圆锥形损坏模型”接触定律结合在一起。对于每种类型的镇流器，都会找到一组参数，从而使模拟和实验结果完全吻合。与简化的Hertz-Mindlin接触定律的比较显示了该模型的几个缺点。首先，无法对模型进行校准以满足压缩和剪切测试结果。其次，使用Hertz-Mindlin模型无法再现剪切测试中的相似行为，但压缩差异。由于这些原因，如果使用简单的粒子形状，则CDM模型被认为是模拟铁路道ast的更好选择。

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