高速铁路沥青砼基床弹塑变形的温度效应模型试验

Temperature effect model experiment of elasto-plastic deformation of asphalt concrete reinforced foundation bed in high-speed railway

沥青砼强化基床表层是一种高速铁路无砟轨道新结构。为掌握极端温度环境与列车长时动载耦合作用对其弹塑性变形的影响规律,开展了"竖向足尺、荷载等效"的大型单元填土模型试验,分析了在25kPa循环荷载作用下沥青砼基床结构的瞬时及永久变形随高温、低温及高低温交替(-30℃~45℃)的变化趋势。试验表明:采用80mm厚沥青砼强化的基床结构弹性变形在0.12mm^0.16mm间变化,浅层弹性变形与环境温度呈正相关性;经过25万次~100万次动载作用,路基面累积变形均呈现初期较快、后期缓慢的非线性发展趋势,且未超过相应环境下的弹性变形,体现出良好的温度适应性;相较于常用的级配碎石型结构,经沥青砼强化的基床,瞬时变形降低约40%,永久变形发展更加平缓,减小23%~59%,抵抗变形能力提升显著。

Asphalt concrete reinforced foundation bed surface is a new structure of ballastless track in high-speed railway. In order to understand the influence of extreme temperature environment coupling action the influence of long time dynamic load coupling action of train its elasto-plastic deformation, a large-scale element fill model experiment with “vertical full scale, equivalent load” was carried out. The variation pattern of instantaneous and permanent deformation of asphalt concrete reinforced foundation bed structure under 25kpa cyclic load and in high temperature, low temperature and high and low temperature alternating (-30-45℃) environment was analyzed, respectively. Experimental results show that the elastic deformation of foundation bed structure reinforced by 80mm thick asphalt concrete varies between 0. 12mm-0.16mm, and the shallow elastic deformation is positively correlated with the ambient temperature. After 250 thousand-1 million times of dynamic loading, the accumulated deformation of foundation bed surface shows a nonlinear development trend: faster in the early stage and slower in the later stage, and it does not exceed the elastic deformation in the corresponding environment, which presents a good temperature adaptability. Compared with common grained crushed stone structure, the instantaneous deformation of the asphalt concrete reinforced foundation bed reduces by about 40%, the permanent deformation development is more gentle, reduces 23% to 59%, and the resistance to deformation is improved significantly.