Analysis on Real-time Monitoring for Freezing and Thawing Process of Highway Subgrade in Seasonal Frozen Soil Area

By laying temperature sensor and single point extensometer in subgrade of highway in typical area of seasonal frost climate, with wireless remote communication link, the data of real-time monitoring on a complete freezing-thawing cycle in the subgrade was obtained,based on which the characteristics thereof,including the freezing and thawing time,the temperature rises and drops,the warming and cooling speed,the frost-heave capacity in each layer and in total,were studied by quantative analysis. From the studies,it was found that the lower part of the roadbed and the end of frost line with water supply were the main positions where frost-heave arises,and the weak intercalated layer arising out of two-way thawing between the upper and lower frozen layers in spring-thawing period,which may lead to reduced bearing capacity of subgrade,should be the concern in frost damage prevention, which may be the important reference to analysis of subgrade freezing-thawing mechanism and control of frost damage.