Abstract Modeling the cyclic shakedown and ratcheting of sand remains a great challenge. An isotropic-kinematic hardening model is presented within the bounding-surface framework. By incorporating new features, a combined isotropic-kinematic hardening rule is extended to the deviatoric stress-ratio space. The hardening rule treats cyclic loading as a sequence of monotonic loading events. The kinematic mechanism of this hardening rule assumes that the bounding surface instantaneously translates from the image point to the stress reversal point when the loading path reverses. Then each stress reversal is regarded as an initiation of a new loading event. In each loading event, the isotropic model, which consists of an open wedge-type surface with a circular deviatoric section, may expand or shrink around a generalized homological center to track the variation in the soil fabric. This isotropic mechanism enables the model to capture the gradual evolution of soil stiffness under numerous loading cycles. By introducing a maximum prestress surface, an additional mechanism is deployed to avoid the overshooting problem and to promote the simulation of the post-cyclic behavior. A unified hardening function is defined in the model for all loading events. After calibrating the basic parameters by monotonic tests, only three extra cyclic parameters are required to describe the cyclic behavior of sand. The model behaviors are validated against serval cyclic triaxial tests. The comparison between experimental and predicted results demonstrates the model capabilities in describing the cyclic shakedown and ratcheting responses of sand.

中文翻译：

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砂土循环安放棘轮的各向同性运动硬化模型

摘要 对沙子的循环安定和棘轮进行建模仍然是一个巨大的挑战。各向同性运动硬化模型在边界面框架内呈现。通过加入新特征，组合的各向同性-运动硬化规则被扩展到偏应力比空间。强化规则将循环加载视为一系列单调加载事件。该硬化规则的运动学机制假设当加载路径反转时，边界表面会立即从图像点转换为应力反转点。然后，每次应力反转都被视为新加载事件的开始。在每个加载事件中，各向同性模型由具有圆形偏截面的开放楔形表面组成，可能会围绕广义同源中心膨胀或收缩，以跟踪土壤结构的变化。这种各向同性机制使模型能够捕捉在多次加载循环下土壤刚度的逐渐演变。通过引入最大预应力表面，部署了一种额外的机制来避免超调问题并促进后循环行为的模拟。在模型中为所有加载事件定义了统一的硬化函数。通过单调试验校准基本参数后，只需要三个额外的循环参数来描述砂的循环行为。模型行为已针对 serval 循环三轴试验进行了验证。