Abstract: The deformation characteristics of subgrade graded gravel can be impaired by the variation of water content due to rainwater infiltration so that the traffic safety is adversely affected. However, there is a paucity of the research that addresses the influence of the water content on the deformation characteristics of subgrade graded gravel. To investigate its deformation characteristics at different water contents, a series of large-scale static and dynamic triaxial tests is carried out. The effect of the water content on the stress-strain relationship and shear strength of graded gravel is explored, and the influence of dynamic stress level on the accumulative strain of the soil is studied based on the results of dynamic triaxial tests. Also, an analytical model which accounts for the influences of water content, dynamic stress level, and cyclic number is proposed. Using parameters obtained by fitting the tests for water contents of 5% and 7.3%, the proposed model is validated by calibrating the tests for water content of 8.6%. Comparison of the proposed model and Gidel model shows that the proposed calculation approach yields better results for various dynamic stress levels and loading cycles. The proposed model can not only avoid the scattering of calculated accumulative strain, but also directly reflect the influence of water content on the accumulative strain.

Key words: graded gravel, large scale triaxial test, water content, deformation characteristic, calculation model