Rock deformation memory effect: applications, experiments and theories

Based on the rock deformation memory effect (DME), the deformation rate analysis (DRA) method is a new method for determining the magnitudes and orientation of the in-situ stress. The DME & DRA method has an inherent advantage over the traditional in-situ stress determination methods. A significant number of successful experiments have been done in many countries. But in China, the DME & DRA method has not been explored and used by now. At the same time, the lack of the experimental and theoretical researches on the rock deformation memory prevents the improvements of the DME & DRA method. A review of application, experimental and theoretical researches on rock DME is given. For the experiments, 7 topics include: (1) features of DRA curve, (2) memory fading, (3) artificial memory and in-situ stress memory, (4) duration of loading application, (5) preload times, (6) stress level memorized by DME, (7) memory under triaxial stress state. Two kinds of mechanisms and the corresponding theoretical models are discussed with their strengths and weakness analyzed. Finally, the necessity and the directions for the future researches are outlined.