Time-dependent Degradation of Material Properties and Associated Creep Behavior in Heterogeneous Rocks

摘要

A numerical model based on time-dependent degradation law was applied in the paper to simulate the time-dependent damage and deformation of rock materials under constant stress levels. An empirical relation between degradation of material properties and applied stress is used to simulate the mechanical behavior of each element of finite element model. The time-dependent degradation law of material is used at the scale of each element to simulate its damage. In modeling, an element is damaged by decreasing its Young’s modulus or strength to simulate the effect of local damage at microscopic scales. Elastic interactions between elements and heterogeneity of material properties lead to the emergence of a complex macroscopic behavior. In particular, the primary and tertiary creep regimes associated respectively with a degradation and increase of the rate of strain, damage event and energy release were observed in the simulations. Damage localization emerges at the transition between primary and tertiary creep, when damage rate starts accelerating. This model can reproduce the three creep regimes and associated damage evolution of rock, which is of great help to investigate time-dependent instability failure mechanisms of rock mass and to prevent associated rock hazards in rock engineering.