Abstract:

In order to know about the rheological properties of rock in a long range of the time scale, method of increasing temperature was brought forward to accelerate the rheological process of rock, which could extend the time scale of experimental test data. Firstly, based on the generalized linear viscoelastic constitutive equation with temperature variable, the creep behavior of rock was divided into three types according to the different strain dependences of the time, that is, Hookean deformation, Newtonian flow, and retarded elasticity. Then the general equivalence relationship between time parameter and temperature parameter was derived for each type of strain. Finally, the relation between time parameter and temperature parameter in the whole creep was considered and the general theory of time-temperature equivalence effect (TTEE) of rock was established. This research reveals: ①The temperature effect on the instantaneous strain could be modified through vertical shift. ②The key point of the TTEE of Newtonian flow depends on whether in the study of linear viscoelastic behavior of rock change of temperature is completely equivalent to a shift of the logarithmic time scale or not. ③By plotting the results of a creep experiment performed at different temperatures and comparing the curves obtained, one can decide whether the rock considered have TTEE. ④The TTEE of the whole creep should satisfy that the horizontal shift function of Newtonian flow and retarded elasticity is consentaneous.

Key words: time-temperature equivalence effect (TTEE), viscoelasticity, rheological property, creep