Research on Compaction and Permeability Characteristics of Gravel Soil Roadbed Filler

Abstract: In order to reveal the rule of particle breakage and loss of crushed stone soil subgrade filler in the process of compaction and seepage, crushed stone soil samples with different stone content and water content were compacted and the compacted seepage test was conducted. The results show that the best compaction effect is achieved when the stone content is 60% for gravelly soil samples with hard rocks and fine particles as sandy soil. The dry density first increases and then decreases with the increase of water content, and the change trend of permeability coefficient and dry density is opposite; The particle size distribution before and after compaction and crushing has good fractal characteristics. The fractal dimension D is positively correlated with the dry density. With the increase of water content, it first increases and then decreases, reaching the maximum at the optimal water content. The optimal fractal dimension D for crushing is 2.23~2.25 for coarse particles and 2.43~2.45 for fine particles; There is also a good linear relationship between the crushing ratio Bg and fractal dimension D. When the stone content is not more than 60%, the D of coarse and fine particles increases with the increase of Bg; The influence of seepage erosion on D is greatly affected by the rock content. When the rock content is 60%, the difference of fractal dimension decreases first and then increases with the increase of water content, which is the same as the change trend of permeability coefficient. When the rock content exceeds 60%, the change range of the difference of fractal dimension decreases significantly. Stone content and water content are two important factors that affect particle breakage and loss. However, compared with water content, stone content has a more significant impact on particle breakage and loss. The fractal dimension D has a good correlation with the compaction and permeability test results of each proportion sample, which can better reflect the compaction and permeability characteristics of gravel soil samples. The research results can further reveal the compaction mechanism of gravel soil subgrade, and also provide reference for subgrade construction.