Simulation Of Subgrade Of High-speed Railway In Seasonal Frozen Region

Frozen soil is extremely sensitive to temperature and its properties are greatly affected by temperature.Frost heave often occurs in cold winter on the subgrade of high-speed railway,and the frozen subgrade thaws in warm spring,which causes frozen diseases,such as mud pumping and irregularity of track.These diseases will threat the safety of high-speed railway.Therefore,it is very important to study how frost heave occurs and the influence factors and find effective anti-frost measures to ensure the stability of subgrade.Based on high-speed railway from Harbin to Qiqihar,the distribution law of temperature and deformation of subgrade is obtained by means of numerical simulation,and then the influence of foam concrete thermal insulation board on the temperature and deformation of subgrade is studied.The main contents and conclusions of this paper include:(1)The temporal and spatial distribution of temperature and deformation field for subgrade in seasonally frozen ground is studied based on the field temperature data.The distribution of the internal temperature time history curve is approximately cosinusoidal.The temperature amplitude decreases with the depth increasing and he temperature vertical transmission has hysteresis.At the beginning of freezing period,the vertical displacement of subgrade increased rapidly.Then the frost heaving rate decreases and the vertical displacement increases slowly.After the vertical displacement reaches to the maximum value,it decreases very fast.(2)On the foundation of the coupled model of temperature-deformation,the law of deformation with frozen depth and the law of deformation of each layer along frozen depth are obtained.The deformation and frozen depth of subgrade are consistent with each other and the deformation increases with frozen depth increasing.(3)The frost heave rate is distributed non-uniformly along the frozen depth and the maximum frost heave rate appears in the range of 2/3 of the maximum frozen depth from the subgrade surface.In this rang vertical displacement reaches to80%~90% of the total vertical displacement of subgrade.(4)The distribution of the temperature and deformation of the subgrade paved by 10 cm foam concrete thermal insulation board is studied,and the influences of the thermal insulation board on the temperature and the deformation of the subgrade are analyzed.After laying the insulation board,the temperature line of the subgrade is raised and the frost depth is significantly reduced.The cycle of frost heave and thaw of the subgrade is shortened,and deformation of the subgrade is decreased.Thus the anti-frost effect of thermal insulation board is effective.