隔热层对季节冻土区无砟轨道路基冻胀防治的适应性分析

Adaptability of Heat-insulating Course to Prevention of Forst Heave of Unballasted Railway Track Subgrade in Seasonal Frozen Regions

结合客运专线无砟轨道路基的工程结构及我国东北地区季节冻土的工程特点,通过对粗颗粒土的室内冻胀试验,得出随着细颗粒含量的增加,粗颗粒土的持水性和冻胀率都相应增大;当粗颗粒土中小于0.075 mm细颗粒含量为5%时,土样经饱和再排水条件下冻胀率为1.31%。根据哈齐客运专线季节冻土区的地质及气候条件,采用有限元数值方法分别对季节冻土区既有和新建的客运专线无砟轨道路基设置隔热层后的路基温度场进行了对比分析,计算结果表明:对于新建路基,在路基面铺设10 cm厚隔热层和保温护坡措施后路基的保温效果良好,可以起到对路基冻害的预防作用;对于既有路基,采用在路基面(轨道板处除外)和边坡位置铺设隔热层措施,路基的保温效果不明显。

In view of the engineering structure of unballasted track subgrade of dedicated passenger lines and the engineering characteristics of seasonal frozen soil in the northeast region of China,the indoor tests of the frost heave behaviors of coarse-grained soil were carried out.The results indicate as follows：Along with increasing of the fine grain content,the frost heave ratio and water bearing capacity of coarse grain soil increase correspondingly;when the content of fine grains of the size less than 0.075 mm reaches 5%out of the coase grain soil and after the test specimen is saturated and drained,the frost heave ratio of the test specimen is 1.31%.According to the geologic and climate conditions of the seasonal frozen regions along the Harbin-Qiqihar Dedicated Passenger Line,the two-dimensional finite element method was adopted to analyze the temperature fields of the existing and newly-built unballarted track subgrade with heat insulating courses for dedicated passenger railway lines across seasonal frost zones.The numerical results show as follows：For newly-built subgrades,the 10mmthick heat insulating course and insulating berm have good insulating effect,so frost prevention can be achieved;for existing subgrades,the heat insulating courses are laid on the top away from track pads and on the slopes and the heat-insulation effect is not obvious.