考虑多种强化机制土的内时弹塑性本构模型

为建立更符合实际情况的岩土的弹塑性应力应变模型,在考虑变形历史、围压、应变率、偏斜塑性变形对体积塑性变形影响引起的多种强化机制的基础上,合理地定义了广义时间标度,建立了考虑多种强化机制土和体量与偏量相互耦合的内时弹塑性本构关系。结合土的静水压缩载荷对偏斜响应影响小,而偏斜压缩载荷对体积响应影响大的实验事实,给出了模型参数分别用静水压缩实验数据和常规三轴实验数据确定的方法。用所建立的考虑多种强化机制的内时弹塑性本构模型对中密永定河砂的三轴响应进行了预测。由模型预测的砂土应力应变曲线与实验相吻合,并且能够较好的描述永定河砂的剪胀和剪缩现象。

An Elastoplastic Endochronic Constitutive Model for Soil Considering Multi hardening Mechanisms

In order to establish an elastoplastic stress strain model for soil which conforms to the actual situation,an elastoplastic endochronic constitutive model was developed incorporating the multi-hardening mechanisms and the interaction between deviatoric and volume deformation by means of properly defining a generalized time scale.Since it has been revealed by experimental results that volume deformation response has little effect on deviatoric deformation response,while deviatoric deformation response has strong effect on volume deformation response,the parameters in this model to characterize the soil behaviors can be determined from the results of isotropic compression and conventional triaxial compression experiments.The comparison between the predicted and measured stress-strain and volume change behaviors for medium-density sand from Yongding River showed that the model was capable of predicting the soil's shear compression and dilation characteristic with good accuracy.