基于胶结破损机理的非饱和结构性黄土本构模型  

Three-Dimensional Constitutive Model of Unsaturated Structural Loess Based on the Mechanism of Degradation Evolution

作　　者：蒋明镜 卢国文[1,2] 李涛 Jiang Mingjing;Lu Guowen;Li Tao(School of Civil Engineering,Tianjin University,Tianjin 300072,China;State Key Laboratory of Hydraulic Engineering Simulation and Safety,Tianjin University,Tianjin 300072,China;State Key Laboratory of Disaster Reduction in Civil Engineering,Tongji University,Shanghai 200092,China;College of Civil Engineering,Tongji University,Shanghai 200092,China)

机构地区：[1]天津大学建筑工程学院,天津300072 [2]水利工程仿真与安全国家重点实验室(天津大学),天津300072 [3]同济大学土木工程防灾国家重点实验室,上海200092 [4]同济大学土木工程学院,上海200092

出　　处：《天津大学学报（自然科学与工程技术版）》2020年第3期243-251,共9页Journal of Tianjin University：Science and Technology

基　　金：国家自然科学基金重点资助项目(51639008,51579178)~~

摘　　要：非饱和结构性黄土本构模型需同时考虑非饱和性和结构性,为简化建模过程,基于实用化宏微观土力学研究思路,以岩土破损力学及临界状态土力学为框架,建立了非饱和结构性黄土的本构模型.通过三维离散元法开展不同含水量结构性黄土数值试验,基于离散元和前人试验结果建议采用幂函数描述吸应力和初始饱和度的关系,从而建立非饱和黄土有效应力公式,进而将临界状态线、扩展椭圆屈服面和临界Lade-Duncan强度准则推广到非饱和土体,以考虑黄土的非饱和性.通过定义与重塑黄土屈服面形状相似的结构性黄土屈服面反映结构性的影响,鉴于室内试验无法直接获取土体胶结破损演化规律,基于离散元分析结果和胶结颗粒材料力学理论,得到具有微观机制的胶结破损规律,该演化规律建立在等效塑性应变上,可以很好地反映结构损伤过程;通过将其引入到硬化规律考虑黄土的结构性演化,从而建立了非饱和结构性黄土本构模型.将该模型应用于Q3天然非饱和结构性黄土三轴试验及人工制备结构性黄土侧限压缩试验和三轴试验模拟,初步验证了该模型的合理性及适用性.A constitutive model of unsaturated structural loess should consider both unsaturated and structural behavior.In order to simplify the modeling process,a practical constitutive model of unsaturated structural loess was established based on the geotechnical damage mechanics and critical soil mechanics in the framework of geomechanics from micro to macro.A three-dimensional discrete element method(DEM)was used to carry out numerical tests of different water content of structural loess.Based on the discrete element and experimental results in the literature,the power function was suggested to describe the relationship between suction stress and initial saturation,so that the effective stress formula of the unsaturated loess could be established,critical state line,extended elliptical yield surface,and critical Lade-Duncan strength criteria were then extended to unsaturated soils to consider the unsaturation of loess.Yield surface of structural loess was defined as similar in shape to the yield surface of remolded loess to reflect the structure,since degradation evolution cannot be applied directly in laboratory tests.Based on the mechanical theory of bond materials and discrete element simulation analysis,the degradation evolution with micromechanism was associated with the equivalent plastic strain,which well reflected the damage process of the structure,and was then introduced into the hardening law.Finally,a constitutive model for unsaturated loess was established based on classical elastoplasty.The constitutive model is preliminarily verified by triaxial test of Q3 natural unsaturated structural loess,compression test and triaxial test simulation of artificial structural loess.

关 键 词：非饱和结构性黄土 破损参数 微观机理 本构模型 

分 类 号：TU43[建筑科学—岩土工程]