NaCl溶液改良膨胀土动力特性试验  

Experimental study on dynamic characteristics of expansive soil improved by NaCl solution

作　　者：李宝平[1] 支枭雄 张玉[1,2] 平高权 杨倩 LI Baoping;ZHI Xiaoxiong;ZHANG Yu;PING Gaoquan;YANG Qian(School of Civil and Architecture Engineering, Xi’an Technological University, Xi’an 710021, China;Shaanxi Key Laboratory of Loess Mechanics and Engineering, Xi’an University of Technology, Xi’an 710048, China)

机构地区：[1]西安工业大学建筑工程学院,西安710021 [2]西安理工大学陕西省黄土力学与工程重点实验室,西安710048

出　　处：《中国科技论文》2022年第7期780-788,共9页China Sciencepaper

基　　金：陕西省教育厅专项科研计划项目(20 JK0670)。

摘　　要：为研究改良膨胀土在循环荷载作用下的力学特性,以陕南膨胀土为研究对象,基于GDS动三轴试验,得到了不同条件下土体的骨干曲线和动阻尼比、动弹性模量、动强度的演化规律曲线,并分析了膨胀土动力学参数随应变、围压和NaCl溶液浓度的变化规律。结果表明:随着动应变(εd)的增加,骨干曲线经过弹性、弱弹性和塑性3个阶段。动弹性模量曲线先急速下降、后缓慢减小并趋于平稳状态。动阻尼比曲线呈现3个阶段,εd<0.1%,增长速率较快;0.1%≤εd≤1.5%,增速逐渐减小;εd>1.5%,曲线趋于平缓。随着围压和NaCl溶液浓度的增大,骨干曲线呈现不同程度的上升,动弹性模量和动强度均增大,动阻尼比减小;改良膨胀土动应变与动弹性模量关系可用Hardin-Drnevich修正线性模型描述;改良土动黏聚力随NaCl溶液浓度的增加不断变大,而浓度对动内摩擦角的影响较小。比较了改良前后膨胀土动变形和动强度特性参数,结果表明:经NaCl溶液改良后膨胀土的动力特性得到显著提高;1.0 mol/L NaCl溶液改良效果最为明显。研究可为陕南地区工程建设提供相关参考依据。In order to study the mechanical properties of improved expansive soil under cyclic loading,the expansive soil in southern Shaanxi was taken as the research object.Through the GDS dynamic triaxial test,the dynamic backbone curve of the soil under different conditions and the evolution law curves of the dynamic damping ratio,dynamic elastic modulus and dynamic strength were obtained.The variation of dynamic parameters of expansive soil with strain,confining pressure and concentration of NaCl solution was analyzed.The results show that as the increase of dynamic strain(εd),the dynamic backbone curve goes through three stages:elastic,weakly elastic and plastic,respectively.The dynamic elastic modulus curve reduces rapidly at first,then it slowly reduces and tends to be stable.The dynamic damping ratio curve shows three stages:εd<0.1%,the growth rate is faster;0.1%≤εd≤1.5%,the growth rate reduces gradually;εd>1.5%,the curve tends to be gentle.With the increase of confining pressure and NaCl solution concentration,the dynamic backbone curve increases in varying degrees,the dynamic elastic modulus and dynamic strength increase,the dynamic damping ratio decreases.The relationship between dynamic strain and dynamic elastic modulus of improved soil can be described by the modified Hardin-Drnevich linear model.The dynamic cohesion of the improved soil increases with the increase of the concentration of NaCl solution,but the concentration has little effect on the dynamic internal friction angle.The dynamic deformation and strength parameters of the expansive soil before and after improvement were compared.It shows that the mechanical properties of the expansive soil improved by NaCl solution are significantly improved.The improvement effect is the best when the concentration of NaCl solution is 1.0 mol/L.The research results can provide relevant reference basis for the engineering construction in southern Shaanxi.

关 键 词：岩土工程 膨胀土 NACL溶液 动弹性模量 动阻尼比 动强度 

分 类 号：TU443[建筑科学—岩土工程]