【作者】 陈菲；

【导师】 王连俊；

【作者基本信息】 北京交通大学 ， 地质工程， 2008， 硕士

【摘要】 京津城际是我国首条开通速度达300km/h的客运专线,线路采用无砟轨道博格板技术,工后沉降应控制在15mm以内,路基主要采用CFG桩复合地基处理形式,但在一些地段采取了CFG+碎石桩复合地基处理形式。基于国内外尚无高速铁路的组合桩复合地基的工程实例,本文依托“客运专线路基沉降控制措施及变形观测技术研究”课题进行北京段CFG桩+碎石桩复合地基沉降特性研究。课题通过对比不同位置桩土应力比及桩土沉降差异,评价了CFG桩及组合桩复合地基在北京段应用效果,并比较两种类型控制沉降的作用效果;通过大量沉降实测数据估算出后期的工后沉降;最后通过Midas-GTS有限元软件,比较分析了组合桩与CFG桩两种复合地基处理效果。通过以上研究,得到了以下初步结论:1、桩承担着大部分荷载,在堆载过程中,桩的部分荷载转移到土体;在该地区填筑路基,其产生的超孔隙水压力很小;在监测段时间内,堆载时间段的沉降量最大,而卸载后,沉降量就很小。2、通过对实测数据进行双曲线法、新野法的预测分析,北京段路基的沉降量均能控制在规范要求15mm之内,说明了当前设计的合理性。3、通过实测数据、数值计算均表明,CFG+碎石桩组合桩的沉降小于唯一的CFG桩地基处理,但作用效果不十分明显。更多还原

【Abstract】 Beijing-Tianjin inter-city rail traffic was the first passenger line opened in China in which the technology of ballastless track and CFG-pile composite foundation were applied. The post-construction settlement should be controled within 25mm. Basing on the gap of CFG-pile composite foundation applied in high railway,settlement characters of composite foundation was studied between Beijing test section, which relied on the subject—study on subgrade settlement control measures and deformation observation technology in passenger line.Then, the effect of CFG-pile composite foundation appiled in Beijing section was evaluated,by comparing pile-soil stress and settlement differences in different location;at the same time,the factors which affect settlement characters and pile-soil stress were researched and a reasonable design parameters were made.The factors they are the length、pile pitch、modulus and thickness of cushion.Based on the above study,some conslusions are below:1、Most of the load was beared by pile,but during the process of preloading.Some load was transferred from pile to soil; ultra-pore water pressure caused was little in the region;the settlement was the largest during the preloading and it was little after the load removed.2、The settlement characters of CFG-pile composite foundation caused by subgrade load were inverted bell-shaped;the surface settlement was the largest at the roadbed centerline;with the distance from the roadbed center increaseing,settlement reduced gradually;there was little ground uplift close to the border region.3、To a certain length,the relationship berween settlement and pile-length is inverse ratio; the longer length, the greater pile-soil stress ratio and the role of pile;the larger distence between pile.the large settlement and pile-soilstress;With cushion modulus increased,the settlement reduced slightly;but the pile-soil stress ratio increase,the impact of cushion thickness on the settlement is not significant,but the pile -soil stress ratio is noticeably affected by the cushion thickness.更多还原