长期交通荷载作用下粉砂土累积变形本构模型构建及数值积分格式

因目前在模拟长期交通荷载作用下粉砂土路基不均匀变形时尚缺乏一套严谨、高效的计算模型,在室内静力及动三轴试验的基础上,通过引入安定性理论,基于弹塑性本构理论框架,提出了一个能合理反映粉砂土复杂变形机理的双屈服面等效黏塑性本构模型。对粉砂土动三轴试验结果的模拟表明,该模型采用完全隐式的积分方法,可任意选取积分步长,计算效率高,模拟效果良好。最后,将该模型在有限元程序中进行了实现,可应用于路基不均匀累积变形的计算。

Constitutive model of silty sands for cumulative deformation under long-term traffic loading and numerical integration

According to a lot of results based on the static and cyclic triaxial test, an equivalent visco-plastic model basing on shakedown theory was proposed to precisely and efficiently model the cumulative deformation of silty sands. The two-surface plastic model can reflect complex deformation features with strain hardening and shear dilatancy. In order to improve the efficiency of the integral step, a fully implicit Euler backward algorithm can be adopted to update non-linear equations. By modeling cyclic test results, the proposed model was verified to be good with better predictions and efficiency. And the integral step could be freely selected to obtain high computation efficiency. Finally, the model was embedded in the code of finite element (FEM) to simulate the uneven deformation of the practical boundary problem under long term traffic loading.