The experiment study of frost heave characteristics and gray correlation analysis of graded crushed rock

Traditionally, fine-grained fillings are considered to be susceptible to frost heave. However, most frost heave deformations appeared in the top layer of subgrade of the Harbin–Dalian high-speed railway (Harbin–Dalian HSR), the first HSR running across cold regions in China, indicating that graded crushed rock may also be prone to frost heave. In order to study the frost heave characteristics of graded crushed rock, a series of laboratory experiments on one-dimensional frost heave were conducted in a closed system. Frozen depth and frost heave deformation during the freezing and the moisture content distribution after freezing in a graded crushed rock sample were analyzed. Different factors critical to the development of frost heave, including cooling temperature, moisture content, fine content, and compactness, were used in orthogonal tests. Each factor had three levels. Experimental results showed that different amounts of frost heave occurred across various combinations of factors and levels. The Gray correlation method, which uses the frost heave ratio as a reference sequence and other factors as comparison sequences, was used to determine the correlation degree among these different factors and the optimal collocation which results in the development of frost heave in graded crushed rock. Results from this analysis indicated that moisture content produces the most significant effect on the frost heave ratio of graded crushed rock and that the moisture content of graded crushed rock should be maintained below 5% in order to prevent frost heave development in cold regions. •Coarse-grained filling experiment showed that frost heave differ with various combinations of conditions.•Moisture content has the most significant impact on the frost heave characteristic of graded crushed rock.