重载铁路基床动力湿化特性试验研究

Experimental study on dynamic slaking deformation characteristics of heavy haul railway subgrade soil

重载化是铁路扩能改造的重要途径,然而轴重增加会加剧重载铁路路基土湿化变形,引起路基的不均匀沉降,影响列车的安全运行。结合朔黄重载铁路路基病害段实际工况,采用GDS动三轴仪进行了室内动力湿化试验,研究了动应力幅值、压实度对土样湿化变形特性的影响。试验结果表明:1一定压实度下,土体动力湿化变形与动应力幅值可采用指数关系拟合;2土体压实度对动力湿化变形有明显影响,压实度大于95%时,动应力对湿化变形的影响显著降低;3存在一个临界的含水率(本试验为15%),土样饱和度低于临界含水率时,动应力对湿化变形影响不明显,而大于时土样湿化变形显著加大;4分级加载试验表明,土体累积变形随动应力增大而增大。

Increasing axle load can be found the most effective way for capacity expansion of railway freight in China.With increase of axle load,however,slaking deformation caused by the coupling reaction of dynamic load and water can lead to uneven settlement in embankment,which heavily affects the running safety. Taking one section with uneven settlement problem in Shuo-Huang line as example,the effect of dynamic stress amplitude and compaction degree of soil on slaking deformation are investigated by dynamic triaxial tests. The results are shown as follows: 1 For certain dry density,the relationship between slaking deformations and dynamic stress amplitude can be expressed by exponential relation. 2 Compaction degree has significant effect on slaking deformation when compaction degree is lager than 95%.3 A critical water content with 15% in this sample,can be adopted to describe the water content effect on dynamic slaking behavior. Obvious deformation occurs when water content is larger than this value. 4 Multi-stage loading tests show that the influence of dynamic stress amplitude should be considered for the accumulated deformation of sample.