关键词: 花岗岩；卸荷；力学实验；变形破坏；能量演化

Abstract: Considering the stress paths of kilometer-deep granite during mining， the triaxial loading and unloading experiments are performed on granite under three stress paths: ascending axial pressure and fixed confining pressure， ascending axial pressure and unloading confining pressure， and fixed axial pressure and unloading confining pressure. The aim is to obtain the deformation and failure characteristics and energy evolution law of rock under mining and unloading conditions. The research results show that under the high confining pressure levels， rock stores more energy before reaching peak failure， and the deformation energy released during failure has a more significant impact on the rock structure， leading to brittle failure of the rock sample. The unloading effect weakens the radial restraint of the confining pressure on the rock sample， causing an increase in radial expansion， and failure occurs at a lower stress level. Furthermore， the rock deformation modulus and generalized Poisson’s ratio reach the extreme point faster， determined by the expansion point， the turning point at which the proportion of elastic energy of the rock sample changes from increasing to decreasing. Compared with the ascending axial pressure and fixed confining pressure test， the ratio of elastic energy to dissipated energy is higher under the unloading conditions， resulting in more severe in rock damage.

Key words: granite; unloading; mechanics experiment; deformation damage; energy evolution