对改进西原模型的再认识

Reevaluation of modified Xiyuan model

从岩石的物理变形机制出发,对改进西原模型的物理意义进行了理论探讨,得出改进西原模型蠕变变形机制是一个强化作用有限发挥、弱化作用累积的过程的结论.分析表明:改进西原模型能够描述简单应力状态下不同应力水平的岩石蠕变特性曲线,在同一应力水平下,可以用蠕变加速度作为判定模型的稳定性判据;将改进西原模型用于直剪蠕变试验,需考虑有效法向应力对长期强度极限的影响,用于三轴蠕变试验,需考虑长期强度极限与围压的关系;对于应变局部化问题,采用改进西原模型必须考虑黏性效应与其他正则化机制的耦合作用.

Based on the mechanism of physical deformation of rocks, the physical meaning of the modified Xiyuan model was discussed theoretically. The creep of the Xiyuan model experiences a process of limited hardening and accumulation of softening. The modified Xiyuan model can describe the creep characteristic curve of rocks at different stress levels in simple stress state, and the creep acceleration can be used to judge the stability of the model at the same stress level. Moreover, if the improved Xiyuan model is applied to direct shear creep tests, the influence of effective normal stress on the long-term strength limit should be taken into account, while the relationship between the long-term strength limit and surrounding pressure should be considered if it is applied to tri-axial creep tests. For the improved Xiyuan modelapplied to the strain localization problem, the interaction between viscosity effect and other regularization mechanism should be taken into account.