Experimental Research on Frost Heaving Characteristics of Coarse Grained Soil Filler of High Speed Railway Subgrade in Cold Region

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.