控制吸力循环荷载下非饱和黏性土的弹塑性双面模型  

Elastoplastic two-surface model for unsaturated cohesive soils under cyclic loading with controlled matric suction

作　　者：李潇旋 李涛[1] 彭丽云 LI Xiao-xuan;LI Tao;PENG Li-yun(School of Civil Engineering,Beijing Jiaotong University,Beijing 100044,China;School of Civil and Transportation Engineering,Beijing University of Civil Engineering and Architecture,Beijing 100044,China)

机构地区：[1]北京交通大学土木建筑工程学院,北京100044 [2]北京建筑大学土木与交通工程学院,北京100044

出　　处：《岩土力学》2020年第2期552-560,共9页Rock and Soil Mechanics

基　　金：国家自然科学基金(No.50579002)。

摘　　要：建立非饱和土在动态荷载作用下的本构模型有助于解决相关的工程问题。在塑性增量流动理论框架内,将BBM(Barcelona basic model)模型与笔者提出的塑性硬化准则相结合,考虑控制吸力的循环荷载作用,建立了一个描述非饱和黏性土的弹塑性双面模型。该模型包含一个边界面和一个几何相似的加载面,二者结合记忆中心的概念,共同描述应力路径周期性改变加载方向时非饱和土的非线性、循环塑性和变形累积特性。采用动三轴剪切试验确定了一种非饱和黏质粉土的动态力学特性,分析了吸力、净围压和动应力幅值对循环塑性的影响。模型预测与非饱和土在静、动态加载下的试验结果的对比显示,二者吻合较好,表明所建立的弹塑性双面模型能够模拟非饱和土在控制吸力循环荷载作用下的力学行为。The constitutive model of unsaturated soil under dynamic loading is helpful to solve related engineering problems.In the framework of plastic incremental flow theory,by combining Barcelona basic model(BBM)with the plastic hardening criterion proposed by one of the authors and considering the cyclic loading with the controlled matric suction,an elastoplastic two-surface model is established for describing unsaturated cohesive soil.Combined with the concept of memory centre,a bounding surface and a geometrically similar loading surface describe the nonlinear,cyclic plasticity and deformation accumulation characteristics of unsaturated soil when the stress path periodically changes the loading direction jointly.Dynamic triaxial shear tests were conducted to determine dynamic mechanical properties of unsaturated clay silt,which analyses the influences of matric suction,net cell confining pressure and dynamic stress amplitude on cyclic plasticity.Experimental results of the unsaturated soil under static and dynamic loading are compared with the correlative model predictions,which shows a good agreement.It indicates that the elastoplastic two-surface model can simulate the mechanical behaviour of unsaturated soil under cyclic loading with controlled matric suction.

关 键 词：非饱和土 循环荷载 基质吸力 塑性硬化准则 弹塑性本构模型 

分 类 号：TU431[建筑科学—岩土工程]