中文摘要：

根据分级加载条件下的蠕变试验，分析研究了无加筋砂土和土工格栅加筋砂土的蠕变特征，发现蠕变变形与分级加载时的应力水平、初始蠕变应变速率有很大关系，且蠕变后以恒定应变速率重新加载时呈现出刚度很大、近似弹性的行为。针对无加筋砂土和土工格栅加筋砂土提出一种弹黏塑性有限元计算方法。有限元计算过程中，砂土和土工格栅均采用统一的3要素弹黏塑性本构模型。该方法能够对含多个蠕变段的恒定应变速率加载全过程进行模拟。通过试验结果与有限元计算结果的比较，表明所提出的弹黏塑性有限元计算方法能较好地模拟无加筋砂土和土工格栅加筋砂土的蠕变特征，特别是蠕变后重新加载时的刚度很大、近似弹性的行为。

英文摘要：

Based on the experimental results of creep tests under step loading in the plane strain compression, the creep behaviors of non-reinforced and geogrid-reinforced sands have been investigated. It is found that the creep deformation is affected by the initial stress level and the initial creep strain rate in a given creep loading stage. When monotonic loading is restarted from the end of each creep loading stage, the stress-strain relation shows a very high tangent stiffness. A nonlinear finite element analysis （FEA） incorporating the unified three-component elasto-viscoplastic constitutive model for both sands and geogrids is developed. The FEA can simulate the whole process including the monotonic loadings at a constant strain rate and the creep loading stages. By comparing the simulated results with the experimental results, it is shown that the developed elasto-viscoplastic FEA can simulate the creep behaviors of non-reinforced and geogrid-reinforced sands very well, especially for the high stiffness following a creep loading stage.