Experimental Study on Cumulative Plastic Deformation of Coarse-Grained Soil High-Grade Roadbed under Long-Term Vehicle Load

According to the change characteristics of the subgrade moisture content and the mechanical calculation of several typical highways, the test scheme of the permanent deformation of coarse soil was formulated. The relationship between the permanent deformation of coarse- grained soil and the stress level, compaction degree, moisture content, and loading frequency was studied by cyclic loading triaxle testing. The results show that the permanent deformation of coarse- grained soil increases with the increase in partial stress and moisture content and decreases with the increase in compaction degree. The experimental data were fitted by the Tseng-Lytton model, and the correlation coefficients were 92%, which indicated that the model could be used to predict the permanent deformation of coarse soil. The relationships between the model coefficient and the moisture content and spring back modulus were obtained by the multiple regression method. Finally, the permanent deformation of the subgrade soil was calculated by using the layered summation method and a typical subgrade pavement structure.