基于改进的Poyting-Thomson蠕变损伤模型研究

Research on creep damage model based on improved Poyting-Thomson

针对原Poyting-Thomson模型不能很好地反映软岩受载蠕变过程中的加速蠕变阶段问题,在原Poyting-Thomson模型的基础上,串联了一个非线性元件,依据能量损伤理论中弹性模量的变化定义损伤变量,构建了一个在软岩受载时,能描述软岩全蠕变变形特征的新蠕变模型,并通过对砂岩的单轴压缩实验来验证构建出的模型的合理性。研究表明,以砂岩试件蠕变时间35 h为分界点,35 h前实验蠕变曲线处于衰减与等速蠕变阶段,35 h后实验蠕变曲线处于加速蠕变阶段,采用ORIGIN绘图软件分别对2个阶段进行模型函数拟合,得出了拟合曲线能够较好地吻合实验蠕变曲线,函数拟合精度高,证明了该模型的合理性。

Aiming at the problem that the original Poyting-Thomson model can not well reflect the accelerated creep stage in the process of loaded creep of soft rock, a nonlinear element is connected in series on the basis of the original Poyting-Thomson model, and the damage variable is defined according to the change of elastic modulus in the energy damage theory.A new creep model that can describe the full creep deformation characteristics of soft rock under load is constructed, the rationality of the model is verified by the uniaxial compression test of sandstone.The research shows that the experimental creep curve is in the stage of attenuation and constant velocity creep before 35 h, and the experimental creep curve is in the stage of accelerated creep after 35 h, taking the creep time of sandstone specimen as the dividing point.The model function fitting of the two stages is carried out by using ORIGIN drawing software, and the fitting curve can well fit the experimental creep curve.The fitting accuracy of the function is high, which proves the rationality of the model.