关键词: 岩石力学, 三轴疲劳, 环向变形, 不可逆变形, 应变速率

Abstract: To research the long-term stability of engineering rock mass under triaxial loading, triaxial compression tests and periodic axial load fatigue tests are conducted on yellow sandstone under different confining pressures. Evolution laws of axial deformation, circumferential deformation and volumetric deformation are obtained. The tests results show that: the axial, circumferential and volumetric deformations of fatigue failure of yellow sandstone under conventional triaxial cyclic loading are controlled by the static complete stress-strain curves. The axial and circumferential peak deformations of fatigue failure and irreversible deformation present an inverted S-shaped law of three stages. The confining pressure can promote the development of the axial deformation, but restrain the development of the circumferential deformation. In fatigue failure deformation process, the development of peak strain ?max is similar to that of the reversible strain ?p, elastic strain ?e remains basically unchanged in three stages, and a change law of irreversible strain increment ??p can reflect the evolvement law of the strain rate in three stages. Deformation is more suitable to be used as a fatigue failure criterion of rock rather than strength, and the fatigue deformation properties of yellow sandstone obtained in this paper make the foundation for the establishment of the fatigue failure model.

Key words: rock mechanics, triaxial fatigue, circumferential deformation, irreversible deformation, strain rate