基于修正塑性功函数的砂土硬软化本构模型

An Elasto plastic Constitutive Model with Hardening softening Behavior for Sandy Soil Based on Modified plastic Work State Function

摘要:

基于与应力路径无关的修正塑性功函数,提出了一个新的可以考虑砂土变形强度应力路径效应的弹塑性硬化软化本构模型.模型所采用的与应力路径不相关的修正塑性硬化函数是基于砂土多应力路径平面应变压缩试验结果、经过数学拟合而得到的.文中建议的本构模型属于等向硬化软化、考虑非关联流动的弹塑性模型.有限元计算结果与室内试验结果比较表明,该模型不仅可以较好地模拟砂土变形强度的应力路径效应,同时也可以模拟砂土变形强度的应力水平依存性、强度的固有结构性各向异性、初始空隙比依存性,以及砂土伴随剪切破坏的软化效应.

Abstract:

A new elasto plastic constitutive model for sand is proposed according to a stress path independent energy based hardening function.A stress path independent relationship between the irreversible strain energy and a stress parameter is formulated based on results from a series of drained plane strain compression (PSC) tests on saturated dense Toyoura sand with precise stress and strain measurements performed along a wide variety of stress path.The model is coupled with an isotropically work hardening and softening,non associated,elasto plastic material description.The FEM code incorporating the above mentioned model is validated by simulating physical PSC tests.The proposed model can better simulate the effects on the deformation characteristics of stress history as well as those of pressure level,inherent anisotropy,void ratio and work softening associated with strain localization into a shear band.