Mechanical characteristics of deep sandstone under different true triaxial stress paths

By using multi-function true triaxial fluid-solid coupling system, the initial in-situ stress reduction tests under different simulated depths and stress paths were carried out for the deep sandstone, and the stress-strain curves of the deep sandstone under corresponding working conditions were obtained. The corresponding deformation characteristics and strength characteristics were analyzed. The results show that: In the process of restoring σz, σy, σx, the σz-Εx, σz-Εz, σz-Εy curves of deep sandstone has the characteristics of platform of different lengths; With the increase of simulation depth, the peak strength of deep sandstone increases; By introducing fracturing coefficient, the results show that the volume deformation from the initial in-situ stress state point to the peak strength point only accounts for 10%-20% of the volume strain of the initial stress state; Under different stress paths, compared with Drucker-Prager criterion, Mogi-Coulomb criterion is more suitable to describe the strength characteristics of rocks under different stress paths. © 2021, Editorial Board of Journal of CUMT. All right reserved.