Abstract: Based on rock energy change theory and tests under three different pressure unloading paths of rocks, the evolution features and rates of absorbing strain energy for compression, the expanding strain energy for circumferential deformation, the elastic strain energy and dissipated energy have been researched. It has been found that during unloading, the absorbing strain energy for compression has mainly turned into expending strain energy for circumferential deformation in three unloading paths, and the expansion degree is path Ⅲ> path I> path II. The quantity of strain energy dissipation can be significantly increased only near the peak. The initial confining pressure’s influence on absorbing strain energy for axial compression, expending strain energy for circumferential deformation and elastic strain energy is significantly higher than that on unloading path, and the three kinds of strain energy are linearly increased as initial confining pressure increases. Under the same initial confining pressure, elastic strain energy stored near the peak size is of the degree of path II> path I> path III, which can draw a conclusion that path II is most likely to have rock burst if there is rock failure. The unloading path and initial confining pressure have significant influence on energy dissipation. Strain evolution rate in three paths all increases with the increase of initial confining pressure, and the effects of the initial confining pressure on the evolution rate of strain energy is in connection with the unloading path.

Key words: different paths, rock, unloading, confining pressure, strain energy, energy evolution