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通过将Perzyna过应力理论与临界状态理论相结合,并引入Wheeler旋转硬化法则,提出一个能描述土体初始各向异性及应力诱发各向异性的三维弹黏塑性本构模型。模型考虑流变发生的下限,在三维应力空间,模型存在形状相似的静屈服面及动态加载面。采用缩放形式的幂函数。本构模型数值算法采用回映算法,借助ABAQUS软件UMAT子程序接口实现。并通过对三轴不排水蠕变试验的模拟,确定合适的积分步长。此后,分别对三轴不排水蠕变试验及常应变率三轴不排水剪切试验进行了模拟。模拟中通过设置不同参数值,可将模型退化为各向同性模型,并对这两种模拟结果进行了比较。模拟结果表明:(1)对于三轴不排水蠕变,在低剪应力水平下,各向同性模型和各向异性模型模拟的结果相差不大,而在高剪应力水平下,各向异性模型模拟结果更接近试验结果;(2)对于常应变率加载试验的模拟,模型合理反映了土体不排水强度随着加载速率的增大而增大现象。
By combining Perzyna stress theory with criticality theory and introducing the principle of Wheeler rotation hardening, a three-dimensional visco-visco-plastic constitutive model that can describe the initial anisotropy and stress-induced anisotropy of soil is proposed. The model considers the lower limit of the occurrence of rheology. In the three-dimensional stress space, the model has similar static yielding surfaces and dynamic loading surfaces. Power scaling function. Constitutive model numerical algorithm using the mapping algorithm, with ABAQUS software UMAT subroutine interface. Through the simulation of triaxial undrained creep test, the suitable integral step is determined. After that, the three-axis undrained creep test and the normal strain rate three-axis undrained shear test were simulated. By setting different parameter values in the simulation, the model can be degenerated into an isotropic model, and the two simulation results are compared. The simulation results show that: (1) For undrained three-axis undrained creep, the results of isotropic and anisotropic model simulations are similar at low shear stress. However, under the condition of high shear stress, anisotropic model The simulation results are closer to the experimental results. (2) For the simulation of normal strain rate loading test, the model reasonably reflects that the undrained strength of soil increases with the increase of loading rate.