级配碎石填料大三轴试验及累积塑性应变预测模型

级配碎石作为重载铁路基床表层的主要填料，其受列车荷载的影响最大。因此，研究级配碎石在循环荷载作用下的动力行为及累积塑性应变演化特征变得尤为重要。首先，通过制备不同细粒含量的级配碎石填料，开展一系列大型动三轴试验，探究细粒含量、围压及动应力幅值对循环荷载作用下试样累积塑性应变的耦合影响机制。其次，基于塑性安定理论，确定不同应力水平下试样的动力行为，得到考虑围压及细粒含量参数的塑性蠕变状态临界动应力计算模型。最后，结合试验数据，建立考虑应力水平及细粒含量参数的塑性蠕变动力行为累积塑性应变预测模型，并明确各参数的物理意义。其研究成果可为既有重载铁路路基健康状态评估及考虑强度、变形综合控制的路基结构设计提供参考。

Large scale triaxial tests on graded macadam filling and its accumulated plastic strain prediction model

Graded macadam fillings, the core filling of heavy haul railway subgrade bed is most affected by the train loading. Therefore, it is particularly important to study the dynamic behavior and accumulative plastic strain evolution characteristics of graded macadam filling under cyclic loadings. Firstly, graded macadam fillings with different fine particle contents were prepared, and a series of large-scale dynamic triaxial tests was conducted to explore the coupling influence mechanism of fine particle content, confining pressure, and dynamic stress amplitude on the specimen accumulative plastic strain under cyclic loadings. Additionally, based on the plastic stability theory, the dynamic behavior of specimens under different stress levels was determined, and the calculation model of critical dynamic stress in the plastic creep state was obtained considering the parameters of confining pressure and fine particle content. Finally, in combination with the experimental data, an accumulative plastic strain prediction model was established considering the stress level and fine particle content parameters for the dynamic behavior of plastic creep, and the physical meaning of each parameter was clarified. The research results can provide a reference for the health status assessment of existing heavy haul railway subgrades and the subgrade structure design considering the comprehensive control of strength and deformation.