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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。
The deformation characteristics of soft soil foundation under long-term cyclic loading are very important. The empirical model is a practical method to predict soil deformation caused by dynamic loads. Although there are many fitting methods, there are still some limitations. According to the curve evolution of dynamic deformation of typical structural clay, by introducing superposition and fusion of exponential type (1) Na? - and exponential hyperbolic function / (1) m mb N (10) c N, Can better describe the cumulative deformation of clay under cyclic loading. The model is not only suitable for the “stable” strain curve with strain limit value, but also can fit the “broken type” under different stress levels. Strain curve. Moreover, the improved model also has obvious superiority to the characterization of the deformation of strongly structured clays with brittle failure characteristics. The dynamic deformation response characteristics of soils under different structural soils and stress levels can all be well described, with Very good universality. In the improved model, the critical dynamic stress of soils can be approximated. In view of the sudden failure of structural soils under dynamic loads and the small axial strain before failure, it is considered that the strain values corresponding to the inflection points of the strain- Strain damage standards.