红黏土土层锚杆界面剪切应力松弛试验及其模型  

Experimental study and model of interface shear stress relaxation behavior of anchors in red clay

作　　者：陈昌富 杜成[1,2] 朱世民 何仕林 张根宝 CHEN Chang-fu;DU Cheng;ZHU Shi-min;HE Shi-lin;ZHANG Gen-bao(Key Laboratory of Building Safety and Energy Efficiency of Ministry of Education,Hunan University,Changsha,Hunan 410082,China;College of Civil Engineering,Hunan University,Changsha,Hunan 410082,China;College of Civil Engineering,Hunan City University,Yiyang,Hunan 413000,China)

机构地区：[1]湖南大学建筑安全与节能教育部重点实验室,湖南长沙410082 [2]湖南大学土木工程学院,湖南长沙410082 [3]湖南城市学院土木工程学院,湖南益阳413000

出　　处：《岩土力学》2021年第5期1201-1209,共9页Rock and Soil Mechanics

基　　金：国家自然科学基金项目(No.41572298;No.51978254);湖南省自然科学基金项目(No.2020JJ5024)。

摘　　要：锚-土界面剪切应力松弛是引起锚杆(索)预应力损失的关键因素。首先,研制了锚-土界面剪切应力松弛试验装置;然后,针对红黏土锚固单元体试样,分级施加恒定的界面剪切位移,获得了锚-土界面剪切应力松弛全过程曲线,并采用坐标平移法将分级加载曲线转化成分别加载曲线;再引入分数阶微积分理论改进黏壶元件,建立了红黏土-锚固体界面剪切分数阶M||N(由Maxwell体和Newton体并联组成)松弛模型,选取部分剪切位移水平下的松弛试验曲线回归分析得到了各模型参数,同时还拟合得到了各模型参数随剪切位移的变化关系;最后,采用建立的松弛模型,对另一部分剪切位移水平下的松弛曲线进行预测。研究结果表明:相比于整数阶M||N模型、Burgers模型以及五元件模型(H||M||M),提出的分数阶M||N松弛模型不仅具有结构简单、参数较少等优点,也具备更高的拟合及预测精度。The shear stress relaxation of the anchor-soil interface is the key factor causing the prestress loss of anchor rod(cable).Firstly,a device for testing the shear stress relaxation of the anchor-soil interface was developed.Secondly,a constant interface shear displacement was applied in stages to the red clay anchored element sample,and the whole process of shear stress relaxation curve of anchor-soil interface was obtained,which can be transformed to the relaxation curve at each specific loading level by using coordinate translation method.Then,the theory of fractional calculus was introduced to improve the viscous pot element,and established the red clay-anchor solid interface shear fractional M||N(composed of Maxwell body and Newton body in parallel)relaxation model.The model parameters were yielded by regression analysis of relaxation test curves under partial shear displacements,and the relationship between the model parameters and the shear displacements was also obtained by fitting.Finally,the established fractional M||N relaxation model was applied to predict another part of the relaxation curve under shear displacement level.By comparing the integer-order M||N model,the Burgers model and the five-element model(H||M||M),the results indicate that the proposed fractional M||N relaxation model not only has the advantages of simple structure and fewer parameters,but also has higher fitting and prediction accuracy.

关 键 词：预应力锚杆 红黏土 锚-土界面 应力松弛 分数阶微积分 M||N模型 

分 类 号：TU470[建筑科学—结构工程]