考虑颗粒破碎引起级配演变的道砟边界面本构模型

Boundary surface model for railway ballast considering gradation evolution caused by particle breakage

道砟即使在低围压下也会产生颗粒破碎,从而改变其原始级配。级配作为道砟的一个重要物理特性,显著地影响着道砟本身物理、力学特性。建立可以反映颗粒破碎引起级配演变的本构模型至关重要。基于Einav的分形破碎指标和土体边界面塑性理论,通过分析道砟三轴试验结果,尝试建立了低围压下可以反映颗粒破碎引起级配演变的道砟边界面本构模型。与试验结果对比发现:模型可以较好地反映道砟在低围压下的应力-应变特性;同时,可以对加载过程中颗粒破碎引起的级配演变进行合理的预测。

Particle breakage can occurs within railway ballast under relatively lower confining pressure,resulting in a change in the particle gradation.Gradation significantly influences the physical and mechanical characteristics of ballast.There is an increasingly urgent need for constitutive modeling of ballast for the prediction of gradation evolution under loading conditions.Based on the triaxial test results of ballast,a boundary surface model for ballast under relatively lower confining pressure is developed by employing the fractal breakage index defined by Einav and the theory of boundary surface plasticity.By the comparisons of experimental results,it is shown that the proposed model can well indicate the stress-strain behavior of coarse aggregate under low confining pressure,and provides a reliable prediction of gradation evolution caused by particle breakage during loading.