循环加载下压实黄土的边界面塑性本构模型

Bounding surface plasticity model of compacted loess under cyclic loading

压实黄土的动应力应变关系预测是黄土高原平山填方工程长期运营涉及的关键问题之一,已有模型预测压实黄土的动本构关系难度较大。该文在边界面塑性框架下,引入动态映射法则,提出了一个反映应变累积的循环加载塑性模量表达式,构建了循环加载条件下压实黄土边界面塑性本构模型,分析了循环应力比与围压对应力应变关系与模量的影响规律,采用压实粉质黄土动三轴试验结果进行了验证。结果表明,该循环加载塑性模量基本反映了压实黄土的应变累积行为,所构建的本构模型考虑了循环应力比对动应力应变关系与模量的影响,可为填方压实黄土长期变形分析提供参考。

The prediction of the dynamic stress-strain relationship of compacted loess is essential in the projects of gully reclamation for farming and cutting mountains for city building in Loess Plateau.It is still difficult to predict the behaviors.To fill the gap,this paper formulates a bounding surface plasticity model for compacted loess subjected to cyclic loading.Specifically,a plastic modulus for cyclic loading is proposed to reflect the behaviors of accumulated strain,and an updated mapping rule is introduced.Furthermore,the influence of confining pressure and cyclic stress ratio on stress-strain relationship and modulus is shown by several case studies,which is verified by experimental tests of compacted loess.The results show that the plastic modulus reflects accumulated strain of compacted loess.The constitutive model considers the effect of cyclic stress ratio on dynamic stress-strain relationship and modulus of compacted loess because of the proposed plastic modulus and updated mapping rule.The results can give reference for analysis of long-term deformation of loess-filled foundation.