Analysis on the Effect of Replacing-Soil Method on Inhibiting Frost Heave of Railway Roadbed in Seasonal Frozen Soil Region

A,B class filler obtained along Shenyang-Harbin Railway was taken as the research object.The effect of silt and clay particle content on the frost heaving characteristics of filling material was investigated with indoor freezing and heaving experiments.The results show that the frost heaving coefficient of the roadbed filling increases with the increase of silt and clay particle content,and the amplitude increases gradually.To prevent the existing subgrade from frost heaving damage,it is necessary to make A,B class filler not contain silt and clay particle,considering the thickness of subgrade bed and the maximum frozen depth of Shenyang-Harbin Railway.The mathematical model of the unsteady phase transition temperature field and the thermo-elasto-plastic frost heave model are employed to calculate and analyze the temperature field,the frost heave stress and the deformation field of the frozen soil embankment during its frost heaving process in the replacing soil test section of Shenyang-Harbin Railway.Results show that about 2 m below the natural ground surface is the freezing-thawing active layer,which is the main factor to induce the frost heave of the subgrade.The embankment will be absent from frost heave deformation if the soil with frost heave sensitivity is excavated and then the non-frost-heave A,B group material is filled in the excavated subgrade bed.Moreover,the tensile stress(tensile strain) zone of the roadbed shifts more than 4 m outward from the toe of the side slopes,reducing the damage to the embankment greatly and enhancing the stability of the roadbed.The calculation results agree well with the actual situation.