The Anti-freeze Expansion Of The Insulation Board And The Dynamic Response Analysis In Seasonal Frozen Soil Subgrade

Harbin-Dalian Passenger Dedicated Line is the first passenger line that is designed and built in severe cold area, which across the severe seasonal frozen soil area of the Northeast Central piedmont. The smoothness and stability of subgrade needs high demands as the high speed of train. As the line across the Songliao plain with shallow groundwater level and the loess possesses frost heaving, economic and reasonable measures must be a key consideration in the design and construction of Harbin-Dalian Passenger Dedicated Line.According to the measured data of test project in Harbin-Dalian Line, it makes a contrastive analysis of distribution of the temperature, frost heave and water content of monitoring sections and explores the role of the insulation board for thermal insulation and anti-frost heaving. Then a numerical calculation model is established by the finite element method to realize the coupling effect of temperature field and stress field in the frozen soil subgrade, study the distribution and change laws of the temperature and frost heave in the frozen soil subgrade and explore the best laying position of the insulation board. At last it makes a simple contrast between the numerical simulation results and field data.Field test and numerical simulation results show that the insulation board plays a significant role in the anti-freeze expansion of subgrade. The maximum frost heaving amount of the surface of the central subgrade with the insulation board makes two thirds of the maximum frost heaving amount without the insulation board. The insulation board with a thicker size has a better effect.The dynamic response of subgrade with train loads is analyzed by the finite element method in this paper. It makes a contrastive analysis of three temperature conditions and studies the change laws of the dynamic response as the depth adds. The results show that the dynamic response of the center of sleeper is larger than the center of roadbed, and the dynamic response of the both sides of roadbed reaches a minimum value. It makes a synergistic effect as two trains operates at the same time.