砂土统一本构模型研究及其三维数值实现

THE UNIFIED SAND MODEL AND 3D NUMERICAL IMPLEMENTATION

基于广义塑性理论与临界状态概念,研究提出了一个统一三维砂土本构模型,通过一组参数实现了砂土由压缩至剪切过程中状态参量的统一表述。基于ABAQUS提供的用户自定义材料子程序UMAT接口,利用Fortran语言编程实现了该三维弹塑性本构关系模型在软件中的二次开发。分别利用Toyoura砂、Fuji River砂以及Tokachi砂的剪切试验数据与数值模拟结果进行对比,结果表明:提出的有限元计算模型可以有效反映加载过程中不同围压和砂土初始密度对应力-应变曲线的影响,能够准确描述密砂的剪胀特性与应变软化特性以及松砂的剪缩特性与应变硬化特性,从而更加真实地反映三维应力状态下土的变形和强度特性。研究成果进一步扩展了ABAQUS在岩土工程中的应用范围,能够为岩土工程领域的数值分析计算提供更加快捷的解决方案。

Based on the generalized plasticity theory and critical state concept,a three-dimensional constitutive model for unified modelling of sand behavior is proposed with a set of material parameters.By the User-defined Material(UMAT)subroutine interface in ABAQUS,the constitutive model of sand is developed and compiled with Fortran.The comparison between the simulations and experimental results of three kinds of sand,i.e.,the Toyoura sand,the Fuji River sand and the Tokachi sand,shows that the finite element method could effectively simulate the stress-strain curve over a large range of confining pressures and initial densities.Therefore,the model can better reflect the deformation and strength characteristics of soil under a three-dimensional stress state,where the phenomenon that loose sand contracts while dense sand dilates under shearing is well described.The research can be further applied to numerical analyses related to geotechnical engineering to provide more efficient and practical solutions.