砂土多机构边界面塑性模型及其试验验证

Multiple mechanism boundary surface plasticity model of saturated sand and its test validation

根据Iai多重剪切机构塑性模型及边界面塑性模型的特点,建立了一个砂土多机构边界面塑性模型。该模型将土复杂的变形机理分解为体积机理和一系列简单的剪切机理。用边界面弹塑性模型模拟多重剪切机构塑性模型中虚拟单剪机构,避免了Iai多重剪切机构塑性模型在利用修正Masing准则模拟虚拟单剪应力-应变关系时确定比例参数的复杂性。根据大量试验资料,建立了液化面参数与归一累积剪切功的关系,能够用较少的参数很好地建立有效应力路径。由于多重机理的特性,该模型能够模拟复杂荷载作用下主应力轴偏转的影响。试验结果表明,应用该模型的计算结果与试验结果有较好的一致性。

According to the characteristics of Iai's multiple mechanism plasticity model and boundary surface plasticity model, a multiple mechanism boundary surface plasticity model of saturated sand is established. The concept of multiple mechanism is used as a vehicle for decomposing the complex mechanism into a set of simple shear mechanisms defined in one dimensional space. Each virtual simple shear mechanism is simulated by boundary surface plasticity model in the virtual stress and strain space, with which the complexity of getting the scale parameters when each virtual simple shear mechanism is simulated by the modified Masing's rule in Iai's multiple mechanism model is avoided. According to a lot of test data, a relation between the liquefaction front parameter and normalized shear work is presented. The effective stress path is well modeled by several parameters. The effect of rotation of principal stress axial directions and large shear displacement of sand in the earthquake induced liquefaction are taken into account at the same time in the model. The computed results are consistent with the laboratory results.