Abstract: To investigate the cumulative deformation characteristics of soil-rock mixed fill under cyclic loading, a comprehensive large dynamic triaxial test was conducted. The objective was to determine the influence of different dynamic stress amplitudes and confining pressures on the axial cumulative strain of the fill, as well as the variation of dynamic pore water pressure. Additionally, a cumulative strain prediction model was analyzed. The test results revealed that the axial cumulative strain of the soil-rock fill can be categorized into three types: plastic stability, plastic creep, and incremental damage, according to stability theory. The specimen’s axial cumulative strain increased with larger dynamic stress amplitudes, but decreased with greater confining pressures. The dynamic pore water pressure curve and the corresponding axial accumulated strain curve displayed the same developmental characteristics. In consideration of the development characteristics of creep-type cumulative strain in soil-rock mixed fill, a modified and improved model was proposed. The feasibility of the model was verified, and it can be effectively applied to strain curves exhibiting plastic creep behavior.

Key words: soil-rock mixed fill, large dynamic triaxial test, axial cumulative strain, dynamic stress amplitude, dynamic pore water pressure, improved model