Dynamic characteristics of coal gangue subgrade filler under traffic load based on the hysteretic curves

Abstract

Traffic cyclic loading is the key factor that leads to the deterioration of the long-term service behavior of subgrade. A series of cyclic triaxial tests was carried out by the large-scale dynamic and static triaxial apparatus (LSDSTA) to study the dynamic behaviors of coal gangue subgrade filler (CGSF) under multi-step cyclic loading using the morphological characteristics of hysteretic curves (MCHC). MCHC was quantitatively characterized by four parameters, i.e., the unclosed degree (εphl), inclination of long axis degree (khl), area (Shl) and fullness degree (αhl). With the increase of dynamic strain, εphl increases exponentially. khl of the coal gangue sample first decreases and then shows an increasing trend with the increasing dynamic strain. The values of Shl are close to each other, and the energy dissipation in the sample is small. However, with the increase of dynamic strain, the specimen failure degree is increased, Shl increases exponentially, and the damping ratio increases. With the increase of dynamic strain, αhl increases approximately linearly. Confining pressure has a certain effect on the four parameters. There parameters can be recommended and used for quantitative analysis the dynamic behaviors of subgrade filler under traffic cyclic loading.