Abstract: Rock mechanics tests and creep tests were performed by using real-time high temperature conventional triaxial test system to probe into the creep characteristics of surrounding rock of water diversion tunnel in central Yunnan Province. On the basis of establishing the rock creep constitutive model, a method for determining the creep parameters is proposed according to the characteristics of creep test curve. The relationship between creep parameters and stress is established by analyzing the variation law of creep parameters under different stress levels. Finally, the modified creep constitutive model is obtained by substituting the expression between each creep parameter and stress into the creep constitutive model. Results demonstrate that the established creep model not only reflects the creep characteristics of decay and stable creep stages accurately, and also overcomes the deficiency of traditional model in describing accelerated creep. Moreover, the creep parameters determined by the proposed method reflect the influence of stress on creep parameters and also the influence of stress state on the regularity of creep deformation.

Key words: surrounding rock of tunnel, mechanical properties, creep test, creep parameters, stress state, Central Yunnan Water Diversion Tunnel