利用动三轴试验,研究路基压实粉质黏土动态回弹模量的影响因素,分析动态回弹模量对偏应力、体应力等因素的依赖关系,通过双因素回归分析,在AASHTO-N37A动态回弹模量预估模型的基础上引入k4项,提出了含四参数的改进模型.为了使该改进模型能有效运用于有限元计算中,基于广义Hooke定律推导了其精确一致切线刚度矩阵,通过编写用户自定义材料子程序(UMAT)将改进模型移植入有限元软件ABAQUS中,分别在单个土体单元和路基路面结构条件下对改进模型进行了计算验证.研究结果表明:四参数改进模型能更好预估粉质黏土在不同压实度下的动态回弹模量,利用二次开发的改进模型在有限元软件中计算得出的土体单元的应力-应变关系与解析解较为吻合,而将改进模型运用于路基路面结构分析可以体现因应力不同造成的回弹模量在路基各个位置的差异,同时能反映车辆荷载作用下回弹模量的演变,实现了模量与应力状态的动态耦合,从而路基路面结构设计提供了更为真实的数值模拟方法.%The factors affecting dynamic resilient modulus of subgrade compacted silty clay were investigated with dynamic tri-axis tests to analyze the dependency of dynamic resilient modulus on deviator stress and body stress.Through the two-factor regression analysis,an improved prediction model with four parameters was proposed by introducing k4 on the basis of AASHTO-N37A dynamic resilient modulus prediction model.In order to apply the improved model in finite element calculation,the accurate consistent tangent stiffness matrix of this model was derived based on the general Hooke law.The improved model was transplanted into the FE software ABAQUS by compiling the user material subroutine (UMAT),the computation validation was made under conditions of a single soil element and a subgrade-pavement structure.The results showed that the four-parameter improved model can better predict the dynamic resilient modulus of silty clay under different compaction levels;the soil body element's stress-strain relation calculated with the improved model developed secondarily agreed well with the analytical solution;the improved model being applied in the analysis of subgrade-pavement structure can reflect differences of the dynamic resilient modulus at different locations of subgrade due to different stresses,and also reflect evolution of the dynamic resilient modulus under vehicle loading to realize the dynamic coupling between stress states and dynamic resilient modulus.The study provided a more actual numerical simulation method for design of subgrade-pavement structures.
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