考虑组构各向异性的超固结黏土亚塑性本构模型

Hypoplasticity Model for Overconsolidated Clay with Consideration of Fabric Anisotropy

摘要

基于亚塑性框架提出了适合描述超固结黏土的各向异性亚塑性本构模型,其能够再现超固结黏土初始各向异性及加载阶段的应力诱发各向异性行为．通过将组构各向异性变量考虑进亚塑性模型结构张量的计算,并定义了组构演化规律,对现有各向异性亚塑性模型加以改进,从而更为合理地描述了剪切强度及应力-应变响应随加载方向的变化规律．本文所提出的组构演化规律同时考虑了应力率和应变率对组构各向异性演化的影响,加载初期应力率对于组构演化的影响较大,随着应力加载过程的进行,应变率对组构演化的影响逐渐增强．通过对比不同的室内试验,可以发现相比较经典的亚塑性本构模型,改进的亚塑性本构模型能更好地再现超固结黏土的各向异性特性．

Abstract

A hypoplastic constitutive model was proposed to describe the anisotropy of overconsolidated clays within the framework of hypoplasticity, which can effectively capture both the initial anisotropy and the stress-induced anisotropy behavior at the stage of loading. By incorporating the fabric anisotropy variable into the structural tensor of the hypoplastic model and defining the fabric evolution law, the existing anisotropic hypoplastic model was improved to provide a more accurate description of variations in shear strength and stress-strain response with the change in loading direction. The proposed fabric evolution law simultaneously accounts for the influences of both the stress rate and the strain rate on fabric evolution. At the early stage of loading, the stress rate significantly affects the fabric evolution, while the influence of strain rate becomes more prominent as the loading progresses. A comparison with various laboratory tests demonstrates that compared with the classical hypoplastic constitutive model, the improved hypoplastic constitutive model can more accurately reproduce the anisotropic behavior of overconsolidated clays.

关键词

黏土 / 亚塑性 / 超固结 / 各向异性 / 组构演化

Key words

clay / hypoplasticity / overconsolidation / anisotropy / fabric evolution

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基金资助

国家自然科学基金资助项目(52178345)