摘要
中强膨胀土区建设高速铁路,路基易产生上拱下沉病害,加剧轨道不平顺性,影响高铁正常运营。抑制膨胀土地基的胀缩变形成为关键技术问题。针对中强膨胀土天然地基和CFG桩加固地基的浸水对比试验,探究加载、浸水、失水工况下地基和路基面的变形特征,地基中含水率随时间和沿深度变化规律。研究结果表明:加载-浸水-干缩阶段,天然膨胀土地基与GFG桩加固地基的变形-时间关系曲线呈“S”型变化。膨胀土地基经CFG桩加固处理后,地基面的变形量较天然地基降低了78.3%~124.4%。加载阶段地基沉降和浸水阶段路基上拱横向近似呈“盆底”状分布;失水收缩阶段,地面收缩变形沿横向呈中间大两端小分布。浸水初期浅层膨胀土含水率快速增加;深层膨胀土的含水率增幅缓慢且少于5%;浸水停止后,浅层膨胀土含水率逐渐降低接近初始含水率,深层膨胀土的含水率增幅缓慢且少于10%。CFG桩能有效抑制膨胀土胀缩变形和控制路基面的上拱变形,满足高速铁路无砟轨道对路基变形控制的要求,研究成果可为中强膨胀土地区高铁路基建设提供技术支撑。
As the high-speed railway subgrade is constructed on the moderate-strong expansive soil ground,embankment uplift and subsidence problems commonly exist. These problems aggravate track irregularity and then affect the normal operation of high-speed rail;therefore, the treatment of expansive soil ground becomes a key technology problem. Field soaking tests on the natural moderate-strong expansive soil ground and composite ground treated by CFG pile were performed. The deformation characteristics of ground with time were investigated under in-service loading, soaking, and drying conditions, and the variations of ground moisture content with time and depth were studied. The results show that the deformation-time curves of natural expansive soil ground and GFG pile-treated ground exhibit S-shaped characteristics. The surface deformation of CFG piletreated ground was reduced by 78.3%~124.4% as compared to that of natural ground. The transverse distribution of the subgrade deformation was approximately “basin” shaped during the loading and soaking stages with greater values found in the middle of the subgrade and lower values on its sides during the dehydration-induced contraction stage. The moisture content of shallow expansive soil increased rapidly during the early stage of soaking. The moisture content of deep expansive soil increased slowly and was less than 5%. After soaking, the moisture content of shallow expansive soil decreased with time and finally approached the initial moisture content. The moisture content of deep expansive soil increased slowly and was less than 10%. The CFG piletreated expansive soil ground can effectively suppress its expansive and contractive deformation and control the up warping deformation of subgrade surface, which can meet the allowable subgrade deformation requirements of high-speed railway ballastless track. The research results can provide technical reference for the subgrade construction of high railway in moderate-strong expansive soil areas.
作者
曹自印
CAO Ziyin(Zhengzhou-Wanzhou Railway Passenger Dedicated Line Henan Co.,Ltd.,Zhengzhou 450000,China)
出处
《铁道科学与工程学报》
EI
CAS
CSCD
北大核心
2022年第12期3467-3476,共10页
Journal of Railway Science and Engineering
基金
中国铁路总公司科技研究开发资助项目(2017G008-B)。
关键词
高速铁路路基
膨胀土
浸水试验
CFG桩加固
变形特性
含水率
high-speed railway subgrade
expansive soil
soaking tests
CFG pile treatment
deformation characteristics
moisture content
