A novel unified loading path design method for rock dynamic and static triaxial loading: An analytical investigation

True triaxial testing technique is one of the research focuses in rock mechanics, where appropriate loading paths are critical for triaxial experiments. However, dynamic true triaxial testing remains at an early stage of development, and conventional loading procedures developed for static tests cannot be directly applied under dynamic loading conditions. Consequently, designing loading procedures applicable to both dynamic and static testing conditions remains a major challenge. In this paper, a methodology for designing unified dynamic and static triaxial loading paths is proposed, and verification tests on sandstone under dynamic and static triaxial compressive loading were conducted, and moreover theoretical analysis of designing parameters was carried out. With regard to the unified loading path, synchronous loading with a designated loading rate ratio among the three axes is adopted as a feasible loading procedure. Meanwhile, based on the stress space visualization, the unified loading path can be represented as a ray in the stress space and thereby can be determined by a pair of equivalent parameters (stress parameters and geometry parameters). The results of verification tests validated the effectiveness of the proposed loading path for rock. Furthermore, parametric analysis is carried out, revealing the transition of different triaxial stress states along with the variation of geometry and stress parameters. Our findings provide a potential framework for comparing the dynamic and static mechanical responses of rocks under identical triaxial loading paths in triaxial tests.