Sand-fines mixtures are commonly used engineered materials, and their mechanical behavior is significantly affected by density, confining pressure, as well as fines content. Although many laboratory tests have been performed on sand-fines mixtures, few works have been conducted on its constitutive law. To adequately describe the mechanical behavior of sand with different fines content, a novel elastoplastic constitutive model was developed for sand-fines mixtures by incorporating an equivalent granular state parameter into Rowe's stress-dilatancy equation, plastic modulus, and in conjunction with the correlation between the critical state and fines content. Subsequently, the Runge-Kutta schemes with automatic error control are adopted for the proposed model and implemented in a finite element code. The performance of the fines-state-dependent model with the Runge-Kutta schemes, in terms of accuracy, efficiency and convergence, is verified by analyzing element scale tests and boundary value problems. The comparisons of simulated and experimental results demonstrate that the fines-state-dependent model can effectively capture the strain hardening (or softening) and contraction (or dilatancy) behaviors of sand-fines mixtures under drained conditions. In addition, the key features under undrained conditions, such as flow, limited flow, and non-flow behaviors can also be reasonably reproduced.

中文翻译：

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细砂混合物弹塑性本构模型的建立与实现

砂-细粉混合物是常用的工程材料，其力学行为受密度、围压和细粉含量的显着影响。尽管已对细砂混合物进行了许多实验室测试，但对其本构律的研究却很少。为了充分描述不同细粉含量砂的力学行为，通过将等效颗粒状态参数纳入 Rowe 的应力-剪胀方程、塑性模量，并结合砂-细粉混合物之间的相关性，开发了一种新的弹塑性本构模型。临界状态和罚款内容。随后，具有自动误差控制的 Runge-Kutta 方案被用于所提出的模型并在有限元代码中实现。通过分析单元尺度测试和边值问题，验证了具有 Runge-Kutta 方案的精细状态相关模型在精度、效率和收敛性方面的性能。模拟和实验结果的比较表明，细粒状态相关模型可以有效地捕捉排水条件下砂粒混合物的应变硬化（或软化）和收缩（或剪胀）行为。此外，还可以合理再现不排水条件下的关键特征，如流动、限流和非流动行为。模拟和实验结果的比较表明，细粒状态相关模型可以有效地捕捉排水条件下砂粒混合物的应变硬化（或软化）和收缩（或剪胀）行为。此外，还可以合理再现不排水条件下的关键特征，如流动、限流和非流动行为。模拟和实验结果的比较表明，细粒状态相关模型可以有效地捕捉排水条件下砂粒混合物的应变硬化（或软化）和收缩（或剪胀）行为。此外，还可以合理再现不排水条件下的关键特征，如流动、限流和非流动行为。