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实际工程的边坡、斜坡以及挡土结构中的土体都存在一个初始剪应力的作用。在初始剪应力的作用下土体会产生较大的残余应变。然而,原始Iwan模型难以考虑这种因素的影响。因此,将软化模型引入Iwan串联模型中考虑循环软化的影响,同时再串联一理想刚塑性元件,模拟循环过程中产生的残余应变;最后,结合Masing准则对软黏土的动应力-应变关系进行了描述。在此基础上,将修正的Iwan模型用于软土层的一维非线性地震反应分析。通过分析发现,当场地存在初始剪应力且受到强震时,土体模型需考虑这种因素的影响,否则可能低估速度及加速度幅值,也会低估最大剪应变幅值。
The actual engineering slope, slope and retaining structure of the soil there is an initial shear stress. The soil will produce larger residual strain under the initial shear stress. However, the original Iwan model is difficult to consider the impact of this factor. Therefore, the softening model was introduced into the Iwan tandem model to consider the effect of cyclic softening, meanwhile an ideal rigid-plastic element was tandemly connected to simulate the residual strain generated during the cyclic process. Finally, the dynamic stress-strain relationship of soft clay description. On this basis, the modified Iwan model is applied to the one-dimensional nonlinear seismic response analysis of soft soil. The analysis shows that the soil model should consider the influence of such factors when the initial shear stress is present on the site and subjected to strong earthquakes. Otherwise, the velocity and acceleration amplitude may be underestimated, and the maximum shear strain amplitude may be underestimated.