重载铁路粗粒土填料动力特性及累积变形分析

重载铁路路基比普通铁路和高速铁路要承受更大的动力荷载，路基本体的动力变形更加明显。重载铁路路基的核心层绝大部分为粗粒土，为了探讨重载铁路路基粗粒土填料在列车往复荷载作用下的变形和强度特性，开展了一系列大型动三轴试验，探讨了不同动应力幅值、不同围压、不同含水率对粗粒土土样累积变形的影响，分析了不同静强度和围压时动强度的特点，并根据粗粒土土样在不同围压和动应力作用下的变形规律，即增大围压或减小动应力有助于增强土体稳定，提出了基于累积变形发展趋势的路基粗粒土变形稳定界限状态和判别准则，并给出了判别准则参数。研究结果对重载铁路路基的动力变形稳定性评价和基于动力变形控制的路基设计具有参考价值。

Analysis of dynamic characteristics and accumulative deformation of coarse-grained soil filling of heavy-haul railway

The embankment of heavy-haul railway is typically subjected to greater dynamic loads than those of conventional and high-speed railways and thus exhibits greater deformations. The majority of heavy-haul railway embankment layers is comprised of coarse-grained soils (CGS). The primary objective of this paper is to investigate the strength and deformation characteristics of such coarse-grained soils under repeated train loading. For this purpose, a series of large-scale laboratory triaxial tests is conducted for the effects of varying dynamic stress amplitudes, confining pressures and moisture contents on the accumulated permanent deformation behavior. The characteristics of dynamic strength behavior with different combinations of static strength and confining pressure levels are analyzed. According to the permanent deformation accumulation characteristics, that is the increase of confining pressure or reduction of dynamic stress is helpful to enhance the soil stability of CGS obtained at different levels of deviatoric and confining stress values, a criterion for determining stable state of CGS is proposed, and the parameters of the criterion are given. The research results contribute to improving evaluation of the dynamic stability of heavy-haul railway embankment and to the establishment of the design philosophy based on the dynamic deformation control.