黏土脏污对道砟集料的应力-剪胀关系影响  

Effect of Clay Contamination on Stress-Dilatancy Relationships of Ballast Aggregate

作　　者：陈静[1,2] 高睿[1,2] 刘洋泽鹏[1,2] 石知政 张荣隆 CHEN Jing;GAO Rui;LIU Yangzepeng;SHI Zhizheng;ZHANG Ronglong(School of Civil Engineering,Wuhan University,Wuhan 430072,China;Key Laboratory of Safety for Geotechnical and Structural Engineering of Hubei Province,Wuhan University,Wuhan 430072,China)

机构地区：[1]武汉大学土木建筑工程学院,湖北武汉430072 [2]武汉大学岩土与结构工程安全湖北省重点实验室,湖北武汉430072

出　　处：《西南交通大学学报》2022年第6期1201-1207,共7页Journal of Southwest Jiaotong University

基　　金：国家自然科学基金(51178358,51878521)。

摘　　要：列车循环荷载下,铁路地基层中的黏土颗粒会逐渐侵入道砟层,降低道床承载性能.通过开展一系列大型直剪试验,对黏土脏污质污染下的受格栅加筋道砟集料和未受格栅加筋道砟集料的强度及变形发展、应力-剪胀关系进行了研究.试验结果表明:随着脏污程度的增加,道砟集料在剪切过程中强度及法向变形均降低;干净道砟集料的应力比与剪胀比呈一阶线性关系,而黏土污染的道砟集料塑性增强,在剪应力峰值状态下剪胀比更高而抗剪强度发展缓慢,导致应力比与剪胀比呈二阶多项式关系;高法向压力下,道砟集料具有更低的剪胀比;黏土脏污质的存在会减小道砟集料的变形破坏速率,但降低了集料的抗剪强度,而格栅的加筋作用可弥补由于黏土脏污引起的强度降低.Clay fines from subgrade would gradually intrude into the ballast layer under cyclic loadings of passing trains,which would reduce the bearing capacity and impede the free drainage of track beds.A series of largescale direct shear tests were carried out to investigate the strength and deformation characteristics and stressdilatancy relationship of the geogrid-reinforced and unreinforced ballast contaminated by clay fines.The results showed that the strength and normal displacement of ballast aggregate decrease with an increase in the contamination level.The stress ratio of clean ballast is linear with the dilatancy ratio,while the addition of clay fines would increase the plasticity of the ballast aggregate.For fouled ballast in the peak state of shear stress,the dilatancy ratio of aggregate increases while the shear strength decreases,and a second-order polynomial relationship between stress ratio and dilatancy ratio is observed.Under a higher normal pressure,the aggregates have a lower dilatancy ratio.The reduction in the dilatancy rate and the shear strength of clay-contaminated ballast can be remedied by the inclusion of geogrid in the aggregate.

关 键 词：格栅加固 道床脏污 直剪试验 应力-剪胀关系 

分 类 号：U213.7[交通运输工程—道路与铁道工程]