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岩石的时温等效效应是指岩石在低温、长时间尺度下与在高温、短时间尺度下的流变力学特性等效的效应。利用岩石的时温等效效应,可以通过提高试验温度方法得到岩石在相对低温下的长期流变力学特性。为研究岩石在非线性黏弹性条件下的时温等效效应,基于Schapery单积分型的非线性本构方程,得到了岩石非线性黏弹性蠕变力学特性时温等效效应的数学表示。根据不同应力及温度下花岗岩的蠕变试验结果,设定20℃为参考温度,考虑温度改变对岩石瞬时蠕变柔量的影响,得到了垂直移位因子随温度的变化规律及修正后的蠕变柔量的时间对数曲线;对修正后的曲线进行水平移位使得相邻温度曲线之间相交于一点,得到不同应力下蠕变柔量的主曲线及水平移位因子的变化规律;主曲线中相邻温度曲线之间的一致性较好,进一步验证了花岗岩时温等效效应的存在性。通过对不同应力下的垂直移位因子和水平移位因子的变化规律分析,发现应力为40～60 MPa之间的非线性并不明显,但到87 MPa,非线性特性明显增强。
The time-temperature equivalent effect of rock refers to the equivalent effect of rock on the rheological mechanical properties at high temperature and short time scale at low temperature and long time scale. By using the time-temperature equivalent effect of rock, the long-term rheological mechanical properties of rock at relatively low temperature can be obtained by increasing the test temperature. In order to study the time-temperature equivalent effect of rock under nonlinear viscoelastic conditions, a mathematical representation of the time-dependent temperature-dependent equivalent effect of rock nonlinear viscoelastic creep mechanical properties was obtained based on the Schapery’s nonlinear constitutive equation. According to the creep test results of granite under different stress and temperature, set 20 ℃ as the reference temperature and consider the influence of temperature change on the instantaneous creep compliance of rock. The law of vertical displacement factor with temperature and the corrected creep The time-log curve of the softening; the horizontal shift of the corrected curve so that the adjacent temperature curves intersect at a point, the main curve of the creep compliance and the variation rule of the horizontal displacement factor under different stress are obtained; The consistency of the adjacent temperature curves in the curve is better, which further verifies the existence of the equivalent effect of the temperature in granite. Through the analysis of the variation law of vertical displacement factor and horizontal displacement factor under different stress, it is found that the nonlinearity between 40 MPa and 60 MPa is not obvious, but to 87 MPa, the nonlinear characteristic is obviously enhanced.