A theoretical model for evaluating the deterioration of mechanical properties of rockfill materials

The mechanical properties of rockfill materials deteriorate when subjected to different environmental factors. Accurately evaluating the deterioration effect on mechanical properties of rockfill materials is crucial for the lifecycle safety assessment of rockfill dams. In this study, we propose a theoretical model that can analyze the deterioration effect on stress and deformation characteristics of rockfill materials caused by weathering. Specifically, based on assumptions of geometric and breakage similarity, the stress and strain tensors of rockfill assemblies before and after deterioration can be derived from granular matter mechanics by introducing a deterioration coefficient. The deterioration coefficient defines the ratio between the grain crushing strength of deteriorated and undeteriorated rock grains, and can be obtained by single grain crushing tests. The deterioration coefficient is introduced into the Duncan-Chang EB model to quantitatively evaluate the deterioration effect on stress and deformation characteristics of rockfill materials. The triaxial test results of deteriorated and undeteriorated rockfill materials are used to verify the model. The results indicate a good agreement between the model predicted results and experimental results. Besides, the deteriorated stress and deformation characteristics of rockfill materials after cyclic wetting-drying are predicted by the theoretical model.