适用于黏土的分数阶应力诱导剪胀方程  

A STRESS-INDUCED FRACTIONAL DILATANCY RULE FOR CLAYS

作　　者：李海潮[1] 马博 张升[1,2] 盛岱超 LI Hai-chao;MA Bo;ZHANG Sheng;SHENG Dai-chao(School of Civil Engineering,Central South University,Changsha,Hunan 410075,China;National Engineering Laboratory for High Speed Railway Construction,Changsha,Hunan 410075,China;School of Civil&Environmental Engineering,University of Technology Sydney,Sydney NSW 2007,Australia)

机构地区：[1]中南大学土木工程学院,湖南长沙410075 [2]高速铁路建造技术国家工程实验室,湖南长沙410075 [3]悉尼科技大学土木与环境工程学院,澳大利亚悉尼NSW 2007

出　　处：《工程力学》2020年第11期108-116,共9页Engineering Mechanics

基　　金：国家自然科学基金优秀青年科学基金项目(51722812);湖湘高层次人才聚集工程项目(2018RS3016);中南大学研究生科研创新项目(1053320170586)。

摘　　要：建立了适用于黏性土的分数阶下加载面模型,该模型所采用的分数阶塑性流动法则能够在不引入塑性势函数的情况考虑塑性流动方向与土体物理屈服面之间的非正交特性,进而统一地描述相关联和非相关联塑性流动法则。基于该流动法则可以得到一个新的应力诱导分数阶剪胀方程以考虑超固结比对黏性土剪胀特性的影响。理论分析结果表明,在相同的应力水平下,土体剪胀量会随着超固结比增大而逐渐减小。相比较修正剑桥模型,该文模型仅额外地引入一个与土体剪胀特性相关的模型参数,并且能够对超固结黏土的应变软化和剪胀特性进行合理的描述。模型计算结果与试验结果对比分析结果表明,该文模型能够准确地描述黏性土在超固结状态下的应力-应变响应和剪胀特性。A fractional sub-loading surface model for clays is developed in the present study.The fractional plastic flow rule adopted in the proposed model is able to account for the non-normality of the flow direction with respect to the yield locus without introducing a plastic potential.Hence,a unified description of the associated and non-associated plastic flow rules is achieved.A stress-induced fractional dilatancy rule can be conveniently derived through the fractional plastic flow rule to consider the effect of the over-consolidation ratio on the dilatancy of clays.The analysis shows that increasing the over-consolidation ratio will reduce the dilatancy under a constant loading pressure.Compared with the modified Cam-clay model,the proposed model introduces only one extra dilatancy-related parameter and can describe the strain-softening and dilatancy features of overconsolidated clays.Model predictions show good agreement with the experimental results,indicating the capability of the proposed model in describing the behavior of clays.

关 键 词：分数阶微分 剪胀特性 下加载面 超固结比 连续方程 

分 类 号：TU43[建筑科学—岩土工程]