中文摘要：

依据粉砂质泥岩三轴压缩蠕变试验结果,分析了岩石的蠕变力学特性。选取线性黏弹性Burgers模型来描述岩石的衰减蠕变和稳定蠕变特性。引入非线性黏塑性元件,将其与Burgers模型串联起来,建立一个新的六元件非线性黏弹塑性Burgers蠕变本构模型。采用非线性Burgers模型来描述岩石的加速蠕变特性。应用Levenberg-Marquardt算法对蠕变试验曲线进行辨识,得出各级应力水平下岩石轴向与径向的蠕变模型参数。对比试验曲线和模型拟合曲线,二者吻合较好,表明线性Burgers模型与非线性Burgers模型可以准确描述岩石3个蠕变阶段的力学特性。模型参数辨识结果表明,在同一级应力水平下岩石轴向与径向的蠕变模型参数各自独立并不统一,模型参数取值时应考虑岩石蠕变的各向异性以及轴向与径向蠕变量、蠕变速率大小的差异。在前7级应力水平下,模型参数应取以轴向应变辨识得到的Burgers模型参数;在第8级应力水平下,模型参数应取以径向应变辨识得到的Burgers模型参数;在破裂应力水平下,模型参数应取以径向应变辨识得到的非线性Burgers模型参数。

英文摘要：

Based on the triaxial creep curves of silty mudstone,the linear Burgers model is selected to describe the characteristics of decaying creep and steady creep of the rock.When the nonlinear viscoplastic component is connected with the Burgers model in series,a new nonlinear viscoelasto-plastic constitutive model is obtained,namely nonlinear Burgers model,which can describe the accelerative creep of the rock well.The Levenberg-Marquardt algorithm is adopted to identify the model parameters,and the Burgers model parameters of the rock under different stress levels are obtained.Comparing testing curves with fitting curves,it is shown that the linear and nonlinear Burgers models are suitable to describe the three creep stages of rocks.The identification results show that the model parameters identified by the axial strain are different from those identified by the radial strain at the same stress level.Therefore,the creep model parameters of silty mudstone should be selected by considering the anisotropic characteristics and the differences of the creep strain and the creep rate between the axial and radial directions of the rock.Under the first seven stress levels,the Burgers model parameters identified by the axial strain should be chosen as the creep parameters of the rock.Under the eighth stress level,the Burgers model parameters identified by the radial strain should be chosen as the creep parameters of the rock.Under the failure stress level,the nonlinear Burgers model parameters identified by the radial strain should be chosen as the creep parameters of the rock.