Permanent deformation and prediction model of construction and demolition waste under repeated loading

This study aims to reveal the macroscopic permanent deformation (PD) behavior and the internal structural evolution of construction and demolition waste (CDW) under loading. Firstly, the initial matric suction of CDW was measured by the filter paper method. Secondly, the PD of CDW with different humidity and stress states was investigated by repeated load triaxial tests, and a comprehensive prediction model was established. Finally, the discrete element method was performed to analyze the internal structural evolution of CDW during deformation. These results showed that the VAN-GENUCHTEN model could describe the soil-water characteristic curve of CDW well. The PD increases with the increase of the deviator stress and the number of cyclic loading, but the opposite trend was observed when the initial matric suction and confining pressure increased. The proposed model in this study provides a satisfactory prediction of PD. The discrete element method could accurately simulate the macroscopic PD of CDW, and the shear force, interlock force and sliding content increase with the increase of deviator stress during the deformation. The research could provide useful reference for the deformation stability analysis of CDW under cyclic loading.