Abstract: The damping parameters including damping ratio and damping coefficient of marble under triaxial cyclic loading were studied through experiments by MTS815 Flex Test GT rock mechanics testing system sets. For the marble under four grades of confining pressures, cyclic loading and unloading was carried out by three levels of dynamic stress under each confining pressure. The regularity in the changes of damping ratio and damping coefficient of marble under triaxial stress and different stress statuses was found as follows: with the increase of loading times, the plastic deformation of rock under the same stress status increased gradually, and the energy dissipation also increased with the rising of σ_max/σ_c and confining pressure σ ₃. Meanwhile, under the same confining pressure, the damping ratio and damping coefficient increased progressively with the increment of dynamic stress amplitude, and accelerated along with the increase of confining pressure. Under the same σ_max/σ_c , the damping ratio and  damping coefficient increased progressively with the rising of confining pressure, and accelerated along with the increase of σ_max/σ_c . Moreover, with the expansion of internal microcrack of the rock and the increase of the quantity and scale of new cracks as well as the irreversible plastic deformation under a cyclic loading of high level stress, the energy dissipation of each cycle increased accordingly.

Key words: rock mechanics, triaxial cyclic loading, damping ratio, damping coefficient, hysteretic loop