Due to its simplicity, the Sanisand bounding surface model was developed for constitutive modelling of sand, which has been widely used. Nevertheless, the model ignored the dependence of yielding on Lode’s angle, sometimes showed a concave plastic potential surface, and had several parameters that required simultaneous identification through trial and error, which could affect model performance. This study aims to refine the model by providing alternative multiaxial yielding and dilatancy relations. This is possible through the definitions of a modified yielding function and fractional stress–dilatancy ratio enriched by fabric-dilatancy tensor. This approach can enhance the model performance and simplify the calibration process. The refined model can simulate various stress paths, stress–strain hysteric loop, unloading-induced contraction, reloading-induced dilatancy, butterfly-shaped liquefaction, etc., of different sands.

由于其简单性，Sanisand 边界表面模型被开发用于沙子的本构建模，该模型已被广泛使用。然而，该模型忽略了屈服对洛德角的依赖性，有时显示出凹塑性势面，并且有多个参数需要通过反复试验同时识别，这可能会影响模型性能。本研究旨在通过提供替代的多轴屈服和剪胀关系来改进模型。这可以通过定义修正的屈服函数和由织物-剪胀张量丰富的分数应力-剪胀比来实现。这种方法可以增强模型性能并简化校准过程。改进后的模型可以模拟各种应力路径、应力-应变滞后环、卸载引起的收缩、