The capability of a discrete element model to predict the constitutive response of a soil is investigated in this paper. The discrete model is constituted of spherical particles with a contact law embedding inter-particle rolling resistance. The study has been carried out in a constrained framework: the complexity of the model is limited in favour of its simplicity of use, the model calibration is independent of the initial state of the soil, the validation of the model has to be robust in the sense that validation loading paths should differ strongly from the calibration loading paths. To reach these objectives, the contact law of the model was slightly enriched with the implementation of a non-constant friction angle, and both porosity and connectivity are controlled for the numerical simulation of the initial soil state. Numerical predictions of the model on the validation loading paths show that such a modelling framework, associating the model itself and the preparation methodology of the numerical sample, leads to good qualitative and quantitative predictions. This is the case in particular for non-rectilinear loading paths or loading paths involving rotation of principal stress axes, while the model is calibrated from monotonous drained triaxial compressions only.

本文研究了离散元模型预测土的本构响应的能力。离散模型由具有接触规律的球形颗粒组成，其中嵌入了颗粒间滚动阻力。这项研究是在一个受约束的框架内进行的：模型的复杂性因使用简单而受到限制，模型的标定与土壤的初始状态无关，模型的验证必须在土壤中可靠。感觉到验证加载路径应该与校准加载路径有很大的不同。为了达到这些目的，通过非恒定摩擦角的实施，模型的接触规律得到了稍微丰富，并且为初始土壤状态的数值模拟控制了孔隙率和连通性。在验证加载路径上对模型进行的数值预测表明，这种建模框架将模型本身与数值样本的制备方法相关联，可以带来良好的定性和定量预测。对于非直线加载路径或涉及主应力轴旋转的加载路径，尤其是这种情况，而模型仅根据单调排水的三轴压缩进行了校准。