Application of Thawing Settlement Coefficient to the Research on the Roadbed Frost Damage of Freeway in Seasonal Frost Region

In the seasonal frost regions, more attention is often paid to frost heave index in the aspect of prevention and cure of roadbed frost damage. Thawing settlement index is rare considered even not. Frost heave test is often used to forecast the heave of field soil. But the lab frost heave test result is difficult to be used to analyze the field condition owing to water migration. Besides water migration, complicated road structure and two\|dimension boundary condition often go against the application of lab frost heave test result. Therefore, lab frost heave index is not enough to analyze and estimate road frost damage. However, the thawing settlement sample is the field frozen soil sample whose freezing course is reliable. The damage of roadbed (for example, fissure, frost boiling, etc. ) is true. At the basis of above comprehension, according to the roadbed boring survey and field observation in several freeways in Jilin Province from 2000 to 2002, the relation between thawing settlement coefficient and water content, dry density and (\%W-W\-0)\% is statistically analyzed. Finally, examples are given, which are able to demonstrate that the spring roadbed boring survey data and thawing settlement coefficient can be used to estimate field thawing settlement amount and frost heave amount, to analyze the causes of roadbed frost damage and to evaluate frost resistance of road constructing material.