冻风积土的塑性损伤阈值及演化规律

发布时间：2018-03-26 14:46

本文选题：道路工程　切入点：塑性损伤阈值　出处：《公路交通科技》2017年09期

【摘要】：为了获取冻风积土在循环逐级加载过程中发生的动力损伤特征,通过对不同负温、围压及振动频率条件下的冻风积土试样进行动三轴试验,测得其动应力-应变曲线。按照冻风积土发生各向同性损伤及塑性应变增量垂直于屈服面的基本假设,利用塑性势函数F(Y,D,σ)相关联流动法则并按照R-O硬化定律建立了冻风积土加载过程中塑性损伤演化模型(P模型)。利用文中提出的有效应力分析方法对试验所测得总动应变中所包含的累积塑性变形部分进行分离,实现了对P模型中参数拟合的目标;根据一、三主应力对D-P屈服边界进行划分以确定加载过程中弹塑性变形特征。通过分析裂隙发展规律研究冻风积土内部塑性损伤演化过程,将累积塑性变形变化率曲线的拐点作为冻风积土发生塑性损伤的阈值,给出了确定初始发生塑性损伤的理论依据。研究结果表明:P模型与相关文献模型确定的塑性损伤变量变化规律具有一致性,为冻风积土路基或基础的动力灾害防治研究提供理论基础。
[Abstract]:In order to obtain the dynamic damage characteristics of frozen aeolian soil during cyclic progressive loading, dynamic triaxial tests were carried out on frozen aeolian soil samples under different negative temperature, confining pressure and vibration frequency. According to the assumption that isotropic damage of frozen aeolian soil occurs and plastic strain increment perpendicular to yield surface, the dynamic stress-strain curves are obtained. The plastic damage evolution model of frozen aeolian soil during loading is established by using the associated flow rule of plastic potential function FKY D, 蟽) and according to R-O hardening law. The total motion measured by the effective stress analysis method proposed in this paper is obtained by using the effective stress analysis method proposed in this paper. The cumulative plastic deformation part contained in the strain is separated, The objective of parameter fitting in P model is achieved, D-P yield boundary is divided according to the first and third principal stresses to determine the elastoplastic deformation characteristics during loading. The evolution process of plastic damage in frozen aeolian soil is studied by analyzing the law of fracture development. The inflection point of the curve of cumulative plastic deformation rate is used as the threshold of plastic damage of frozen aeolian soil. The theoretical basis for determining the initial plastic damage is given. The research results show that the variation law of plastic damage variables determined by the proportion P model is consistent with that of the related literature model. It provides a theoretical basis for the study of dynamic disaster prevention of frozen aeolian soil subgrade or foundation.
【作者单位】：辽宁工程技术大学土木工程学院;
【基金】：国家自然科学基金项目(51504125) 高等学校博士学科点专项科研基金联合项目(20112121110004)
【分类号】：U416.1

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