Seasonally frozen soil is distributed widely in the Northeast China. The prevention measures against the frost heave of graded crushed rock

which is used as the filler of surface layer in subgrade

are crucial to high-speed railway constructed in seasonally frozen soil region due to the strict requirements of subgrade deformation. In order to study the frost heave characteristics of graded crushed rock under different conditions

water content

fine content

cooling temperature and compaction are chosen as influential factors of frost heave characteristics. The closed system laboratory frost heave experiments have been performed based on the orthogonal design

showing that different frost heave amounts appear in different combinations of factors and levels. The frost heave ratio of most graded crushed rock samples is small when water content is 5%

and it exceeds 1% when water content is above 7%. The temperature field

frozen depth

frost heave deformation process and water content distribution in sample after freezing are analyzed. It is found that the water content is greater than the initial water content at the cold side

and is lower than initial water content at the warm side. Using the frost heave ratio as a reference sequence and other factors as comparison sequences

the correlation degrees among water content

fine content

compaction

temperature at cold side and frost heave ratio are analyzed with the gray correlation method. The results from this analysis indicate that water content produces the most significant effect on the frost heave ratio of graded crushed rock. The water content of graded crushed rock should be maintained below 5% in order to prevent frost heave development in the cold regions.