基于Burgers模型考虑损伤的非定常岩石蠕变模型

A non-stationary model for rock creep considering damage based on Burgers model

Burgers模型只能描述岩石蠕变的前两个阶段,为了描述蠕变全过程,考虑蠕变参数的时间效应及损伤带来的影响,采用非定常黏性元件取代Burgers模型中串联的定常黏性元件,使其能描述加速蠕变阶段。根据损伤变量的变化特征,假定了一个函数,经过Lemaitre应变等效原理,代入Kelvin模型可得到能描述蠕变衰减阶段的模型。试验数据拟合结果显示,改进的Burgers模型能很好地描述加速蠕变阶段,模型拟合曲线与试验曲线基本吻合,相关系数高,参数取值也在合理范围内;非定常Burgers模型更适合描述不同应力下的岩石蠕变特征曲线。

Burgers model could only describe the first two stages of rock creep, it is difficult to reflect the accelerate creep stage. In order to describe the whole process of creep and expand its range of application, considering time effect of creep parameters and the effects caused by damage, the following methods should be taken to improve the Burgers model: non-stationary viscous element is used to replace stationary viscous element in a series of Burgers model so as to describe the accelerate creep stage. At the same time, according to the change of damage variable characteristics, a function is assumed and can be put into Kelvin model by Lemaitre strain equivalence principle; finally got the model to describe the creep decay stage. Through combining all divisions, a non-stationary model for rock creep considering damage is obtained. Through analysis, the results show that: the accelerate creep stage can be well described by improved Burgers model; the non-stationary Burgers model curve and experimental curve both approximately consist with each other; the correlate coefficient is high and all parameters are in reasonable ranges. Therefore, the non-stationary Burgers model is feasible and correct; in addition, it is more suitable to describe creep curve of rock under different stress states. © 2016, Science Press. All right reserved.