Dynamic characteristics and constitutive model of improved coarse-grained roadbed filler under traffic cyclic loading

Based on the orthogonal experimental design method, the dry density of each specimen of coal gangue roadbed filling was obtained by the compaction experiment. The maximum dry density of the sample was obtained as follows, fly ash 3%, lime 9%, water 12%, soil 5%. The larger hysteresis loop area indicates the bigger energy consumption of the specimen under a traffic load. The degree of damage to the specimen deepens as the dynamic strain increases, the hysteresis loop area gradually increases, and the damping ratio grows. The smaller hysteresis loop area occurs with the larger the confining pressure. The inclination degree of the long axis of the specimen first rapidly decreases and then tends to flatten with increasing dynamic strain. As the confining pressure of the specimen increases, the inclination degree of the long axis of the hysteresis loop gradually increases. As the dynamic strain increases, the non-closure degree of the hysteresis loop increases approximately linearly. The larger the amplitude of dynamic stress is, the greater the residual deformation generated by the roadbed filling material will be. With increasing confining pressure, the non-closure degree of the hysteresis loop decreases continuously. As dynamic strain increases, dynamic stress also increases. Under increasing confining pressure, the material's failure occurs at a higher level of dynamic stress. An improved Hardin-Drnevich model was introduced to express the relationship between dynamic stress and dynamic strain for coal gangue roadbed filling material under traffic cyclic loading conditions. Additionally, it is observed that the damping ratio diminishes with increasing dynamic strain and confining pressure.