动力UH模型  

Dynamic UH model

作　　者：姚仰平[1] 万征[1] 秦振华[1] 

机构地区：[1]北京航空航天大学交通科学与工程学院,北京100191

出　　处：《世界地震工程》2010年第4期55-59,共5页World Earthquake Engineering

基　　金：国家自然科学基金项目(50879001;10872016;11072016)

摘　　要：针对砂土在动力荷载作用下所表现出的应力诱导各向异性,以改进后的UH超固结土模型为基础,采用旋转硬化规则将其扩展为可考虑与砂土应力应变关系的动本构模型。主要改进有3方面:(1)将形状固定的椭圆屈服面改变为可变屈服面,椭圆的形状由β来刻画,而β本身是椭圆旋转轴的大小,表示应力诱导各向异性程度的大小;(2)引入旋转硬化规则,使椭圆屈服面可围绕原点旋转以反映反向加载条件下的本构响应;(3)对统一硬化参数进行了修正,首先对潜在强度公式增加了一个参数α用来调节超固结应力比参数R对于潜在强度值的影响,其次针对应力诱导各向异性建立起能反映旋转硬化与等向硬化相协调的扩展统一硬化参数。模型预测与试验结果的对比以及有限元模拟表明:提出的动力统一硬化(DUH)模型能够简单、合理的描述与砂土在动力载荷下的本构关系,验证了所提模型的合理性。UH model for overconsolidated clay is extended to a dynamic UH constitutive model considering the stress-strain relationship for both clay and sands by adopting rotational hardening rule.Dynamic UH model is aimed at the stress-induced anisotropy for the both clay and sands under dynamic loading condition.Three aspects are revised in this paper.First,the fixed shape of ellipse yielding surface is revised as the changed shape of yielding surface.The value of β is used to describing the shape of yielding surface.The value for rotational axis of yielding surface can be denoted by β,which means the degree of stress-induced anisotropy.Second,the constitutive relationship for the both clay and sandsoils under reversing loading condition can be simulated by introducing rotational hardening.Third,the unified hardening parameter is revised by adding a parameter α for adjusting the overconsolidated stress ratio R which can influence the value of potential strength.The extended unified hardening parameter with considering rotational hardening and isotropic hardening is established for aiming at stress-induced anisotropy.The comparison results between model predictions and test results and the simulated results by FEM indicate the simplicity and reasonability of the proposed model which can be used to describe the constitutive relationship for both clay and sandsoils under dynamic loading condition.

关 键 词：应力诱导各向异性 旋转硬化 动本构 砂土 

分 类 号：TU392.1[建筑科学—结构工程] P315.97[天文地球—地震学]