The creep parameters of rockfill are usually derived from creep test in the laboratory, in which the loading period before the creep stage is much shorter than the construction period in the field. This difference might cause underestimation of the long-term settlement of high rockfill geostructures if an elastic-viscoplastic model based on isotach assumption is adopted. This paper aims to investigate this hypothesis. A time-dependent strain hardening model is proposed to simulate the creep behavior of rockfill based on the relationship between the macro- and micro-responses of crushable particles during triaxial creep test revealed by previous DEM study. The results of triaxial creep tests on various granular materials are used to validate the model. The time size effect is highlighted by comparing the predicted long-term deformation of rockfill using the proposed model and an existing isotach model. The results show that the isotach model tends to underestimate the long-term deformation of high rockfill geostructures in the field compared with that of the proposed model, even when both models are calibrated against the same laboratory test results.

堆石料的蠕变参数通常来自实验室蠕变试验，其中蠕变阶段前的加载周期远短于现场施工周期。如果采用基于等距假设的弹粘塑性模型，这种差异可能会导致对高堆石土结构长期沉降的低估。本文旨在研究这一假设。基于先前 DEM 研究揭示的可压碎颗粒在三轴蠕变试验期间的宏观和微观响应之间的关系，提出了一种瞬态应变硬化模型来模拟堆石料的蠕变行为。对各种颗粒材料的三轴蠕变试验结果用于验证模型。通过比较使用所提出的模型和现有等轴距模型预测的堆石料长期变形，时间尺寸效应得到了强调。结果表明，与所提出的模型相比，等距模型倾向于低估现场高堆石料地质结构的长期变形，即使两个模型都根据相同的实验室测试结果进行校准。