一种改进的岩石黏弹塑性加速蠕变力学模型

An improved accelerated creep mechanical model of viscoelasto-plastic rock

为了全面描述岩石蠕变全过程,克服线性牛顿体不能准确描述加速蠕变的不足,在引入非线性蠕变体模型基础上,结合流变力学模型理论,定义应力与试件长期强度的比值为加速蠕变速率幂级数n,模型发生加速蠕变时的总蠕变量为蠕变特征长度εc,进而得到一种改进的能够描述岩石黏弹塑性加速蠕变的力学模型。结合东乡铜矿砂质页岩单轴压缩下分级增量循环加卸载蠕变试验,对模型参数的辨识进行解释,并将该模型的蠕变拟合曲线与实验的蠕变曲线进行对比。研究结果表明:该模型能很好地描述了岩石的加速蠕变特性。

In order to depict the process of rock creep comprehensively, and overcome the deficiency of the linear Newton fluid which can not describe accelerated creep accurately, based on the mature rheological model, the nonlinear creep body model was introduced. In this model, the total creep strain before accelerated creep stage was defined as the characteristic length of creep, and the ratio of stress level and long-term strength of rock specimens was defined as accelerated creep rate. The improved rheological mechanics model was established that can describe the viscoelastic-plastic characteristics of accelerated creep. Combined with the uniaxial compression creep test under multi-step incremental cycling loading and unloading on the sandy shale from Dongxiang Copper Mine, the parameter identification of the mechanical model was explained, the experimental creep curve was compared with the creep fitted curve obtained by the model. The results show that the accelerate creep properties of rocks can be described effectively by this improved creep model.