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Lots of high-speed railway subgrades have been built in the severely cold region in China. The water-proof and drainage system with frost heave prevention structure and micro frost heave coarse-grained filling material with good frost-resistance performance have been widely used in these regions, which can generally solve the problem of high-speed railway subgrade frost heave in the seasonally frozen region. However, the long period monitoring of high-speed railway subgrade indicates that there are still some frost heave problems existing in the seasonally frozen region and this can cause the irregularity problem to the high-speed railway lines which cannot be totally ignored. A new experimental system has been built, which can investigate the frost heave characteristic, the permeability and the water retention capacity of coarse-grained soil. The influence of the fine particles filling material, the permeability and the water content to the frost heave deformation have been tested and analyzed. The water retention ability of different soil is also analyzed. Based on the characteristic of water movement of subgrade in the frozen period and the interactive affection among the water, ice and soil particles; the frost heave development mechanism of micro frost heave coarse-grained filling material is discussed. This achievement can provide scientific evidences, in order to optimize and improve the frost heave prevention filling material and structure.

The Haerbing-dalian high-speed railway subgrade packing is as the research object. Influence factors of frost damage are analyzed, such as packing soil(size composition,Mineral composition,compactness),moisture,temperature external load and salt content, etc. Through characteristic tests of frost heaving, research on Influence of subgrade frost heave with or without the condition of train load conditions was made, including content of fine grained soil, water-holding capacity, packing grading, permeability coefficient, freezing time, condition of water replenishing, etc. Results have shown that:Group A,group B and graded gravel packing moisture rate are between 5.5% ~7.9%;With the reduction of fine aggregate under gravel level,rate of filler frost heave gradually decreases,but frost heave still exists under the condition of low temperature even if fines content is small;The overlying pressure plays a restraining role to the frost heaving of packing;Freezing rate has a great impact on the rate of frost heaving;When cooling rate of 0.2℃/h is 1.77 times faster than that of 1.0℃/h,frost heave quantity increased significantly;When the permeability coefficient is more than 10-3 , soil frost heave coefficient is less than 1, this kind of soil belongs to weak frost heaving soil.