复杂应力路径下土的统一硬化方程

Unified hardening equation for soils in complex stress paths

在建立土的弹塑性本构模型时,需要具体确定屈服函数、塑性势函数,硬化规律及与之相配套的硬化参量,那么硬化参量计算公式的建立就显得尤为重要。首先通过类比正常固结土和超固结土应力–应变关系及强度特征,结合理论推导,给出考虑初始状态影响的统一硬化方程的构造过程;其次,基于复杂应力路径下超固结土强度特性的机制分析,引入可同时考虑初始状态和加载过程影响的土的强度势MY,并通过在原统一硬化方程中采用MY替换强度参数Mf得到复杂应力路径下土的统一硬化方程;最后,通过与各种应力路径下试验结果的对比,验证新的统一硬化方程对建立土的本构模型的意义。

The determination of yield function,plastic potential function,hardening law and corresponding hardening parameter is essential when establishing elasto-plastic constitutive model for soils.Consequently,the establishment the calculation formula of hardening parameter is particularly important.In this paper,through the comparison of the stress-strain relationship and strength behavior of normal and over consolidated soils,the construction of the unified hardening equation considering the influence of initial state is presented.Then,based on the mechanism analysis of strength behavior of over consolidated soils under complex stress paths,the strength potential MY which can consider the joint effects of initial state and loading process is introduced.Additionally,the unified hardening equation for soils under complex stress paths is obtained through replacing the Mf with MY in the original unified hardening equation.Finally,the significance of the novel unified hardening equation to the establishment of constitutive model for soils is verified by comparing with the experimental results under various stress paths.