中文摘要：

软土地基在长期循环荷载作用下的变形特性十分重要,经验模型是动荷载引起的土体变形预测的实用方法,虽拟合方法众多,仍存在一定的局限性。根据典型结构性黏土的动力变形的曲线形态演化规律,通过引入指数型函数（1）Na？-与指数双曲线函数/（1）m mb N（10）c N的叠加融合,提出了一种能更好描述在循环荷载作用下黏土累积变形的改进模型,该模型既适用于具有应变极限值的＂稳定型＂应变曲线,也能拟合不同应力水平下的＂破坏型＂应变曲线。不仅如此,该改进模型对呈脆性破坏特征的强结构性黏土变形特性表征也具有明显的优越性,对于不同结构性土体与应力水平下土体的动力变形响应性状均能较好描述,具有很好的普适性。改进模型可近似计算土体的临界动应力,针对动荷载下的结构性黏土破坏突然且破坏前的轴向应变较小,认为宜用应变-振次曲线拐点对应的应变值来确定相应土体应变破坏标准。

英文摘要：

The deformation characteristics of soft foundation subjected to long-term cyclic loading is significant. Various models have been developed for predicting cumulative plastic strain in clay under repeated loading. The most commonly used is empirical model, but it has some limitations. Based on the dynamic deformation curve of typical structured clay, an improved model is proposed to describe the cumulative deformations of clay subjected to cyclic loading, by adding exponential function of（ 1）Na ？- to the exponential hyperbola model of /（1）m mb N（10）c N. This model applies to both stable strain curve with the strain limit and destructive strain curve under different stress levels. As for brittle failure of strong structured clay, the model has obvious advantages, and it also shows good universality of dynamic deformations of different structured clays under different stress levels. What is more, the improved model can be used to calculate the critical dynamic stress approximately. Since the behavior of structured clay is damaged promptly under dynamic loads when cumulative plastic strain is relatively small, the inflection point of strain-cyclic number curve is proposed to determine the failure criteria of strain.