周期性纵向荷载下散粒体道床阻力试验研究

摘要

Based on a full-scale test model of ballast track structure,an experimental study was carried out on the longitudinal resistance characteristics of granular bed under cyclic loading with different loading rates and displacement extremes,to investigate the deformation behavior and resistance characteristics of the granular ballast bed.The results showed that the plastic deformation of ballast bed was accumulated under monotonic cyclic loading,resulting in the increase of the amplitude of the ballast resistance.Under the cyclic loading,the unloading curve of the granular ballast bed did not coincide with the loading curve of the ballast bed,forming a hysteresis curve.With the increase of the number of cycles,the ballast bed reflected cyclic softening properties.The responses of ballast bed deformation to different deformation rates and stress levels under cyclic loading were different.The cyclic softening behavior of the granular ballast bed changed with deformation levels.The larger the deformation levels,the more severe the cyclic softening of the ballast bed.%基于有砟轨道结构足尺试验模型,开展不同加载速率和位移极值的周期性纵向荷载下散粒体道床纵向阻力特性试验,探讨散粒体道床在周期性循环荷载下的变形特征及阻力特性.结果表明:单调反复荷载会造成道床塑性变形的不断积累,从而使得其阻力幅值增大;散粒体道床在周期性荷载下的卸载曲线与加载曲线不重合,形成一条闭合的滞回曲线,随循环周次的增加,道床体现出循环软化特性;周期性循环荷载作用下,散粒体道床的响应程度与位移幅值和加载速率有关;散粒体道床的循环软化行为依赖于外加位移幅值的大小,外加位移幅值越大,循环软化越严重.