砂土的次加载面动本构模型  

Subloading Surface Constitutive Model of Sands

作　　者：徐舜华[1] 郑刚[1] 刘富勤[2] 

机构地区：[1]天津大学建筑工程学院,天津300072 [2]湖北工业大学土木工程与建筑学院,武汉430068

出　　处：《武汉理工大学学报》2010年第1期152-157,共6页Journal of Wuhan University of Technology

基　　金：天津市自然科学基金(07JCZDJC09800);天津市科学技术创新特别基金(07FDZDSF01200)

摘　　要：基于临界状态土力学框架,建立了一个适用于往返循环荷载作用的砂土次加载面本构模型。模型采用无弹性域假设,认为土体受到反向荷载的瞬时就产生塑性变形,砂土的弹性区域退化为一个点。根据试验结果,屈服面采用倒子弹头型。由于砂土的孔隙比与固结压力不存在唯一的关系,这样使得屈服面大小与孔隙比不能直接耦合,因而硬化规律不是剑桥模型的体变硬化,而是采用增量形式的塑性偏应变硬化表达式。流动法则采用加入状态参数概念的修正的Rowe应力剪胀关系。该模型能考虑砂土变形特性对密度和固结压力的双重依赖型,能合理地模拟砂土动荷载下的应力-应变关系曲线的光滑性、变形积累性、滞洄性。Based on the framework of critical state soil mechanics,a new subloading surface plastic model for sand,being applicable to cyclic loading,is proposed.No elastic region hypothesis is given in this model,so elastic region of sand reduces to a point.Sand simultaneously exhibits elastic and plastic deformation when unloading.Reverse bullet-shaped yielding surface is adopted to ensure accurate prediction of the behavior of sand.No unique relationship between void ratio and the mean normal stress for sand prevents the direct coupling of yield surface size to void ratio,incremental deviatory strain hardening rule is used.The model combines the concept of state-dependent dilatancy by incorporating state parameter in Rowe＇s stress dilatancy equation,which accounts for the dependence of dilatancy on the stress state and the material internal state.The cyclic plastic models can well describe smooth,masing rule and ratchet effect of stress-strain curve.

关 键 词：剪应变硬化 临界状态 次加载面模型 状态参数 剪胀 

分 类 号：TU43[建筑科学—岩土工程]