一种新的岩石非线性损伤蠕变模型

为描述岩石加速蠕变阶段的非线性变形规律,在广义开尔文体基础上串联一个村山体,基于Kachanov损伤率理论,建立了损伤变量D与蠕变时间的函数关系,并根据Lemaitre应变等效原理将村山体中的无损模型参数p用有效模型参数p(1-D)代替,以此来表征岩石加速蠕变阶段的非线性,建立了一种新的非线性损伤蠕变模型;根据广义塑性力学理论给出了该模型的三维蠕变方程;采用Levenberg-Marquardt非线性优化最小二乘法对红砂岩和绿片岩常规三轴压缩蠕变试验数据进行拟合,反演得到这两种岩石的蠕变模型参数。拟合结果表明:拟合曲线与试验曲线的拟合相关系数R2分别为0.999和0.992,说明该蠕变模型能较好地反映这两种岩石各阶段的蠕变曲线特征。

A new nonlinear damage creep model of rocks

In order to describe the nonlinear characteristics of the accelerated creep stage of rocks,a Schiffman body is connected in series on the basis of the generalized Kelvin model.Based on the damage rate theory proposed by Kachanov,the expressions of rock damage variables and creep time are established according to the Lemaitre strain equivalence principle,the non-destructive model parameter p in the Schiffman body is replaced by the effective model parameter p(1-D)to characterize the nonlinearity of the accelerated creep stage of the rocks.The nonlinear damage creep model is established and the three-dimensional creep equation of the model is given according to the generalized plastic mechanics theory.By taking the least square embedded in Levenberg-Marquardt algorithm to fit the compression creep test results of red sandstone and green schist,and the creep model parameters of the two rocks are obtained.The fitting results show that the correlation coefficients of fitting curve and test curve are 0.999 and 0.992,respectively,which indicate that the fitting curves agree well with the experimental curves.It can be concluded that the creep model can well reflect the creep curve characteristics of each rock.