【摘要】 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。更多还原

【Abstract】 Initial shear stress has effect on soils in side slope,sloping ground and retaining wall,etc.Serious residual strain will occur in soft clay under initial shear stress.But,original Iwan’s model ignored this effect.In this paper,an empirical degradation model of soft clay has been incorporated into Iwan’s series-parallel model to account for cyclic degradation.Simultaneously,an ideal plastic element is paralleled to simulate the development of residual strain.Subsequently,the dynamic stress-strain relationship of each soft clay stratum is described with modified Masing’s rules.In this paper,a modified Iwan’s model is utilized in one-dimensional seismic response analysis.It’s observed that the constitutive model should consider this effect when initial shear stress existed and the earthquake is strong.Otherwise,velocities,accelerations and shear strains may be underestimated.更多还原