振动荷载作用下重载铁路路基粗颗粒土填料临界动应力试验研究

Testing research on critical cyclical stress of coarse-grained soil filling in heavy haul railway subgrade

由于重载铁路路基表层为粗颗粒土填料,直接承受轨道结构传递的列车动载往复作用,其临界动应力会影响累积变形,利用自行开发的动三轴试验系统进行不同围压、动应力幅值、含水率条件下粗颗粒土填料的持续振动试验,获得粗颗粒土累积动应变与振次关系曲线,并分析围压、含水率对累积动应变增长影响;在获得不同含水率条件下粗颗粒土的临界动应力比线基础上提出计算临界动应力经验公式。

The surface layer of heavy haul railway subgrade is mainly composed of coarse-grained soil （CGS）. The accumulative deformation characteristic of CGS is a very important issue because the CGS directly supports the cyclical train loading transfered by upper structure. Previous researches reveal that critical cyclical stress ratio （CCSR） is a significant factor of accumulative deformation characteristic. By using a self-developed dynamic triaxial testing system, some sustained vibration tests were carried out on CGS with different confining pressures, dynamic stress amplitudes and water contents. Some curves of accumulative dynamic strain versus vibration times were obtained by the tests. The influences of confining pressure and water content on the increase of accumulative dynamic strain were discussed. Furthermore, the CCSR lines of CGS with different water contents were acquired. Finally, an empirical formula for calculating the critical cyclical stress was put forward.