Abstract: To explore the effect of pore water pressure on shear creep characteristics of rock mass structural planes, an integrated die for fabricating structural planes and a JAW-600 multifunctional shear rheometer were independently developed. The shear creep tests were carried out on serrated structural planes under pore water pressure. The effects of pore water pressure on creep deformation characteristics, creep rate and long-term strength of structural planes were analyzed. The experimental results show that the structural planes under different pore water pressures have experienced instantaneous deformation, deceleration creep and steady creep stages successively, and the increase of pore water pressure promotes the development of the non-linear characteristics of the structural planes; the instantaneous displacement, creep displacement and steady creep rate of the structural planes gradually increase with the increase of pore water pressure, while the creep time, failure stress and long-term strength decrease with the increase of creep strength. According to the test results, considering the influence of pore water pressure on the model parameters, the instantaneous shear modulus, viscous shear modulus and viscous coefficient in the creep model are replaced by the function of pore water pressure, and a structural plane creep model reflecting the influence of pore water pressure is constructed. The model parameters are identified by the optimization analysis software, and the correctness and applicability of the model are verified by comparing the creep test curve with the theoretical model fitting curve. The research results provide some theoretical guidance for the long-term stability analysis of rock mass under the action of groundwater.

Key words: pore water pressure, structural plane, shear creep, test, creep model