地铁循环荷载下黏土污染圆砾的大型动三轴试验及动力特性研究  

Large-scale dynamic triaxial tests and dynamic characteristics of clay contaminated round gravel under subway cyclic load

作　　者：马少坤[1,2] 田发派 黄海均 张加兵 段智博 龚健 MA Shaokun;TIAN Fapai;HUANG Haijun;ZHANG Jiabing;DUAN Zhibo;GONG Jian(School of Civil Engineering and Architecture,Guangxi University,Nanning 530004,China;Guangxi Provincial Key Lab of Engineering Disaster Prevention and Structural Safety,Guangxi University,Naning 530004,China;School of Civil Engineering,Tsinghua University,Beijing 100084,China)

机构地区：[1]广西大学土木建筑工程学院,南宁530004 [2]广西大学工程防灾与结构安全重点实验室,南宁530004 [3]清华大学土木水利学院,北京100084

出　　处：《振动与冲击》2024年第7期245-254,共10页Journal of Vibration and Shock

基　　金：国家自然科学基金(52268062,52108367);广西自然科学基金重点项目(2020GXNSFDA238024);广西重点研发计划项目(GUIKEAB22080061);广西交通运输行业重点科技项目(GXJT-2020-02-08)。

摘　　要：为揭示地铁循环荷载作用下受黏土污染圆砾的长期动力特性,利用GDS大型三轴循环试验系统,开展了一系列饱和不排水动三轴试验,分析了不同围压及动应力幅值下黏土污染水平(clay fouling level,VCI)对圆砾长期动力特性的影响。试验结果表明:随着VCI的增加,试样的累积塑性应变呈先增后减的趋势,污染黏土由润滑作用转变为填充作用,围压为100 kPa时,界限VCI=30%,围压为200 kPa、300 kPa时,界限VCI=20%;VCI对浅埋地铁隧道(σ_(3)=100 kPa)影响较大,威胁行车安全,而对深埋地铁隧道(σ_(3)=200 kPa、300 kPa)影响较小,地铁运行相对安全;随VCI的增加,试样的弹性应变和动孔压比先增大后减小,而回弹模量则先减小后增大,但三者的变化趋势均随围压的降低及动应力幅值的增大愈发明显。研究成果可为地铁路基结构设计及其工后沉降预估提供参考。Here,to reveal long-term dynamic characteristics of clay contaminated round gravel under subway cyclic load,a series of saturated undrained dynamic triaxial tests were conducted using GDS large-scale triaxial cyclic testing system.Effects of clay fouling level(VCI)on round gravel long-term dynamic characteristics under different confining pressures and dynamic stress amplitudes were analyzed.Test results showed that with increase in VCI,cumulative plastic strain of samples has a trend of firstly increasing and then decreasing,contaminated clay action changes from lubrication to filling;when confining pressure is 100 kPa,the limit VCI is 30%,and when confining pressure is 200 kPa and 300 kPa,the limit VCI is 20%;VCI for shallow buried subway tunnels(σ_(3)=100 kPa)has a larger impact to treat driving safety,while VCI has a smaller impact on deep buried subway tunnels(σ_(3)=200 kPa or 300 kPa),and subway operation is relatively safe;with increase in VCI,elastic strain and dynamic pore pressure ratio of samples firstly increase and then decrease,while rebound modulus firstly decreases and then increases,but change trends of the three become more obvious with decrease in confining pressure and increase in dynamic stress amplitude;the study results can provide a reference for design of subway subgrade structures and their post-construction settlement predictions.

关 键 词：循环荷载 圆砾 黏土污染水平(VCI) 动力特性 

分 类 号：TU435[建筑科学—岩土工程]