Microscopic modeling of the creep behavior of rockfills with a delayed particle breakage model

The aim of this study was to develop a practical way of modeling the time-dependent behavior of rockfill materials and to provide useful information that is difficult to obtain from physical tests. Because the micro-mechanism governing the time-dependent rockfill behavior is delayed particle breakage, an updated rock aging model is implemented in an existing code. Particle breakage is represented by the failure of zero-thickness cohesive interface elements that are pre-inserted into the finite element discretization associated with each particle. With only three additional parameters together with temporal integration, we can account for the aging of rock blocks under various stress states and climatic conditions. A series of two-dimensional simulated creep tests were performed on a dense assembly of polygonal particles. By varying rock aging parameters, we can reproduce the typical creep behaviors. The effects of weathering and cyclic loading are investigated by performing five comparative creep tests. The influences of the stress level on the creep deformation are in agreement with experimental observations. A multi-stage creep test is also conducted to verify that the creep behavior has stress history dependence.