The discrete-element method (DEM) was used to simulate constant-volume (undrained) triaxial compression tests for coarse particles (sand) mixed with non-plastic fines. Simulations were performed on granular mixtures with a range of fines contents (f_c) – namely, 0, 0·05, 0·10 and 0·20. The critical state and micromechanical responses of these mixtures were evaluated. The influence of f_c on sand behaviour was captured when f_c < f_thre, where f_thre represents a threshold fines content, which corresponds to a transition from a fines-in-sand soil matrix to a sand-in-fines soil matrix. The DEM was utilised to assess the micromechanical participation of fines within the sand skeleton (matrix). Such evaluations led to assessing the performance of the equivalent granular void ratio (e*), the equivalent granular state parameter (ψ*) and ultimately their inherent parameter b, which represents the proportion of fines actively participating in the sand skeleton structure. It was observed that through capturing the stress partition of contact types within granular mixtures, a reasonable approximation of the active proportion of contacts within the sand matrix could be obtained. This led to a new DEM interpretation of the b parameter. The study therefore evaluated the concept and applicability of the equivalent state theory for sand–fines mixtures.

中文翻译：

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沙子与非塑料细粉混合物的等效状态理论：DEM研究

离散元素方法（DEM）用于模拟与非塑料细粉混合的粗颗粒（砂）的恒定体积（不排水）三轴压缩试验。对具有一定范围的细粉含量（f _c）– 0、0·05、0·10和0·20的颗粒混合物进行了模拟。评价了这些混合物的临界状态和微机械响应。当f _c  <  f _thre时，捕获了f _c对沙质行为的影响，其中f _thre代表细粒含量的阈值，其对应于从细粒土壤基质到细粒土壤基质的过渡。DEM用于评估砂骨架（基体）中细屑的微机械参与。这样的评估导致评估等效颗粒空隙率（e *），等效颗粒状态参数（ψ *）以及最终其固有参数b的性能。，代表积极参与砂骨架结构的罚款比例。观察到，通过捕获颗粒混合物中接触类型的应力分配，可以合理地近似砂基质内接触的有效比例。这导致对b参数进行了新的DEM解释。因此，该研究评估了砂粉混合物的等效状态理论的概念和适用性。