湛江黏土的蠕变模型与变参数塑性元件

Creep model of Zhanjiang clay and plastic components with variable parameters

湛江黏土的蠕变变形在低偏应力下较小,其蠕变等时曲线没有明显的屈服特征而近似为直线,表现为线性蠕变性状;当偏应力达到某一临界值后,在短时间内发展到加速蠕变阶段并发生破坏。从湛江黏土蠕变各阶段的变形机制出发,通过引入服从Mohr-Coulomb塑性流动规律的变参数塑性元件,将该塑性元件与广义Kelvin模型串联,提出描述蠕变全过程的黏弹塑性模型。同时将该模型在FLAC3D中进行二次开发,与FLAC3D中自带的Cvisc模型进行对比验证,结果表明,基于变参数塑性元件的黏弹塑性模型能较好地描述湛江黏土各个蠕变阶段的变形性状。

The creep deformation of Zhanjiang clay is small in the range of low deviatoric stress; its isochronal curve of creep approximates to line without obvious yield characteristics, and demonstrates linear creep behavior. Whereas the deviatoric stress exceeds a critical value, the creep deformation increases to accelerating creep phase in a short time; and the soil mass failure occurs. Based on the creep deformation mechanism of each phase of Zhanjiang clay, the plastic components with variable parameters are introduced and assumed to be in absolute accordance with the plastic flow law of Mohr-Coulomb; the components are combined with the generalized Kelvin model; and the visco-elastoplastic model of Zhanjiang clay is put forward to describe the overall process of creep. In addition, the suggested model is developed in FLAC^3D and compared with the Cvisc model; the results of numerical analysis indicate that the former is felicitous to characterize the each phases of creep deformation behavior of Zhanjiang clay.