Abstract:

With the creep test data of granite taken from Three Gorges, the existence of time-temperature equivalence effect (TTEE) of granite is investigated. Based on the creep test data at different temperatures, which are 20 ℃, 60 ℃, 80 ℃, 100 ℃, 200 ℃, 300 ℃, four-component viscoelastic Burgers model is presented to characterize the creep curves. The parameters of elasticity modulus and viscosity coefficient in the constitutive model at different temperatures and their functional dependences on temperature are obtained. Then, according to the basic theory of TTEE presented in research (I), the TTEE of granite is investigated through modifying the compliance curves with vertical shift function and checking the coincidence of the modified curves with horizontal shift functions. It is concluded that: ① Burgers model could appropriately characterize the creep property of granite in a short time scale. ② Both elastic modulus and viscosity coefficient in the Burgers model decay exponentially with temperature. ③ The coincidence of the curves at different temperatures after vertical shift modification and horizontal shift is fine, which indicates the existence of TTEE of granite. ④The master curves which reflect the long time scale test data at temperatures 20 ℃, 100 ℃, 200 ℃ are obtained.

Key words: granite, time-temperature equivalence effect (TTEE), viscoelasticity, Burgers model