Abstract：Based on the comparative analysis of different failure properties and macro-fracture angles of conventional triaxial compression tests and unloading confining pressure tests at the pre- and post-peak of marble，the methods are proposed to calculate the shear fracture energy according to the bifurcation behavior of complete procedures. The development of shear fracture energy during these processes is obtained. And then，the fact that rock specimens of unloading confining pressure tests at the pre-peak are destructed more intensely than those of unloading confining pressure tests at the post-peak is investigated.
