Study On The Frozen Depth Of Cement Concrete Roads In The Seasonal Freezing Region

Temperature is the dynamic of moisture migration in the soil, as well as determinant of the phase transition of water. It affects the seasonal freezing and melting of subgrade directly. Studying on the temperature field of subgrade and distribution of road freezing depth has great significance on researching the subgrade stability of seasonal frozen region. This paper used cement concrete road of seasonal frozen region as research object, conducted field test and numerical simulation for the temperature field of subgrade;established road freezing depth model for concrete pavement of various pavement structure combination, investigated the distribution law of frost depth, obtained the following results:1) Established a non-steay temperature field modling companied by pahse transition under different boundary conditions,according to the principle of boundary layer,presented the determination of the first boundary condition;determinations of the second and the third boundary condition were based on the boundary condition of solar ridiationg converted into Heat flux and the boundary condition of temperature difference between earth and air as well as the effect of wind speed and direction converted into convective heat thransfer.2) Based on the temperature field test data of the ji-ne highway subgrade in Heilongjiang,the change law of the temperature field on the subgrade in the region of seasonal freezing is analyzed.The unsteady temperature field model accompanied by phase is used to carry out numerical simulation of the subgrade temperature field on the testing section,under the first boundary condition and the situation that the second and the third boundary condition superimposed.The results showed that the temperature field computed result under the second and the third boundary condition is closer to the measured value.3) Under the second and third boundary condition,according to the typical cement concrete pavement of Hailer,Harbin,Erenhot and Altay calculated the frost depth of concrete cement road in this four area. Analyzed the influence law of location,pavement structure and pavement thickness on frost depth.4) Based on the current weather information, we select 18 typical seasonal frozen regions, under the second, third boundary conditions, figure out the frost line of the typical structure of cement concrete pavement and analyse the impact of the boundary conditions to the frost line.5) Based on the road frost line of 18 typical seasonal frozen regions calculated in the chapter four, put the Kriging method into use,draw the road frost line isogram of the cement concrete pavement.