循环荷载下级配碎石填料累积塑性应变及破坏规律研究

Research on Accumulative Plastic Strain Behavior and Failure Properties of Graded Macadam Filling under Cyclic Loading

级配碎石作为重载铁路路基基床的核心填料,在大轴重列车循环荷载作用下的动力稳定性对于整个路基结构的服役性能至关重要。为探究循环荷载作用下级配碎石填料的累积塑性应变演变特征及破坏规律,以不同细粒含量的级配碎石为研究对象,开展一系列不同应力水平下的大型动三轴试验。试验揭示了细粒含量、围压、动应力幅值对该填料累积塑性应变及临界动应力的影响机制,并基于试验结果,提出不同深度级配碎石填料考虑细颗粒含量参数的临界动应力计算公式,明确了式中各参数的物理意义。研究成果有助于预测重载列车动力荷载作用下基床土体的变形,并对评价既有线路开行大轴重列车的适用性提供参考。

The dynamic stability of graded macadam,as the core filling of heavy haul railway subgrade bed,under the cyclic loading of large axle trains,is crucial to the service performance of the whole subgrade structure.To investigate the accumulative plastic strain variation characteristics and failure properties of graded macadam under cyclic loading,a series of large-scale cyclic triaxial tests under different stress levels were carried out for graded macadam with different fine particle contents.The influence mechanism of fine particle content,confining pressure,and dynamic stress amplitude on the cumulative plastic strain and the critical dynamic stress of the filler were obtained.Based on the experimental results,considering the parameters of fine particle content,the formula to calculate the critical dynamic stress of graded crushed stone filler with different depths was proposed and the physical meanings of each parameter in the equation were clarified.This study can help to precisely predict the deformation of subgrade soil under dynamic load of heavy haul train,and provide reference for evaluating the adaptability of running heavy haul train on existing railway lines.