【作者】 陈虎；

【导师】 罗强；

【作者基本信息】 西南交通大学 ， 道路与铁道工程， 2013， 博士

【摘要】 高速铁路路堤多采用优质填料填筑并进行密实压实。依据高速铁路设计技术标准构建而成处于正常状态的路堤型路基结构,长期使用过程中的沉降主要由地基引起。在地基土层变化较大处、不同地基处理措施连接处等路堤地基通常存在较大差异沉降,特别是路基与桥梁交界处的不连续,极易产生明显的路基面不均匀变形,进而导致严重的轨道不平顺问题。地基的差异沉降最终通过路堤反映到路基面,在路堤的传递扩散作用下,路基面的变形形态及不均匀的程度往往不同于地基面。京沪高速铁路采用的CRTS II型板式无砟轨道,为约束桥上纵连式无砟轨道结构因温度变化引起的变位,在路桥连接处的路基一侧设置了由摩擦板、过渡板和端刺等构成的长约60m的端刺结构纵向传力锚固体系。端刺结构的设置改变了柔性路堤与刚性桥台直接连接的传统路桥过渡段基本形式。开展CRTS II型板式无砟轨道路桥过渡段振动响应测试分析,掌握振动响应沿线路纵垂向的空间变化特征及与行车速度的关系,对改善端刺结构两端与相邻路桥结构间的纵向连续性有重要意义。论文在综合参考了国内外有关研究成果的基础上,对高速铁路路堤地基差异沉降传递规律及CRTS II型板式无砟轨道路桥过渡段的动力学性能进行了试验研究,主要开展了以下几方面的工作：1.路堤地基差异沉降传递规律的土工离心模型试验研究为研究路堤地基差异沉降在路堤中的传递扩散特性以及对路基面不均匀变形的影响规律,首先将路堤地基差异沉降简化为错台式与渐变式两种差异沉降模式。通过一套自行设计制造的能够在离心机运转状态下,可控制地基差异沉降大小的土工离心模型试验实时精确控制设备,开展了路堤高度分别为3m、6m、9m及地基差异沉降渐变段长度分别为4m、8m、12m的6组土工离心模型试验,重点研究了地基差异沉降引起的路基面不均匀变形沿线路纵向的分布特点。分析了路堤地基差异沉降量大小、路堤高度、地基差异沉降渐变段长度等对路基面不均匀变形的影响。结果表明：地基差异沉降引起的路基面不均匀变形沿线路纵向均呈“S”型分布特征；路基面不均匀变形的折角与地基差异沉降的幅值基本呈线性关系；路基面不均匀变形的折角相同时,高路堤或在路堤底部设置渐变段均会增大地基差异沉降允许值；基于路基面不均匀变形的折角限值,提出了考虑上覆路堤高度及在路堤底部设置渐变段的地基差异沉降控制限值,对完善铁路路基沉降变形控制的参数指标体系有重要意义。2.路桥过渡段现场长期测试及沉降评估分析结合京沪高速铁路的建设,在高资东特大桥京台和天津特大桥沪台路桥过渡段,开展了基于传感器网络自动测试系统的现场原型长期测试试验。利用京沪高速铁路JHTJ-5标段的沉降评估数据,选取了77个有代表性的路桥过渡段进行了桥台及相邻路基沉降变形数据统计分析。测试分析结果表明：过渡段路堤地基及路基面的沉降变形较小,处于稳定收敛状态,满足设计控制值要求,地基处理措施和路堤填筑技术发挥了明显效果；路堤与桥台间垂向差异沉降随时间增长而逐渐增大,并较快趋于稳定,延长路基放置时间有助于减小过渡段工后差异沉降;路堤填土含水量呈现夏季大冬季小的周期性变化现象,并表现出路基表层的含水量变化受季节影响相对较大、随深度的增加逐渐趋于稳定的趋势；桥台的高度和桥台桩基础的深度对桥台沉降影响不大,过渡段地基的沉降随路堤高度及地基加固深度的增大而呈现出小幅增加的趋势；路桥过渡段的沉降沿纵向从桥台至路基逐渐增大,观测期路基面纵坡的变化值为0.03‰～0.44‰,小于路桥过渡段对折角1‰的要求。3. CRTS II型板式无砟轨道路桥过渡段动力学测试分析结合京沪高速铁路先导段联调联试及综合试验,在濉河特大桥沪台开展了93车次高速运行条件下的路桥过渡段振动特性测试。获得了最高速度达到424km/h的CRTS II型板式无砟轨道路桥过渡段动力响应试验数据。重点测试了CRTS II型板式无砟轨道端刺结构两端与相邻路桥结构连接的关键部位振动位移、振动速度、振动加速度等振动响应,分析了振动响应沿线路纵垂向的空间变化特征及与行车速度的关系。测试结果表明：沿线路纵向的振动响应最大值出现在过渡板端与路基支承层交接处,并呈现出前者支承刚度小于后者的现象；垂向多层的线路结构振动响应沿深度呈递减趋势,结构各层位水平向不连续引起的振动效应表现出与振动源距离成反比的关系,轨道板端经纵联后的振动特性有显著改善；随车速的提高,振动位移表现出线性增加、振动速度与振动加速度呈现出非线性加速增大的规律。4.车辆荷载作用下无砟轨道路基力学响应的双弹性地基模型分析方法为研究车辆轴载通过无砟轨道系统传递到路基结构的荷载作用特性,引用Winkler弹簧地基上无限长梁模型和Hooke弹性地基的Boussinesq解,运用迭代算法,以地基系数为控制条件,构建了应用Winkler弹簧地基和Hooke弹性地基计算双块式无砟轨道路基在车辆荷载作用下的力学响应分析方法(双弹性地基模型分析法)。计算分析表明：车辆轴重对路基结构应力和变形的影响十分显著,路基结构应力和变形随轴重的增加呈线性增大；轨道刚度对路基面应力和变形影响显著,随轨道刚度的衰减,路基面承受的应力和变形均随之增大,轨道板和支承层断裂等极端情况时尤甚；增加支承层的宽度能显著减小路基面的应力和变形,而增加道床板的宽度则效果不明显；基床表层厚度的变化对路基面的应力和变形影响较小,而基床模量的降低则会显著减小地基支承刚度。更多还原

【Abstract】 Most of high-speed railway embankments are constructed with high quality filler and high compaction degree. The embankment is constructed according to the design technical specifications of high speed railway and in the normal state, its settlement is mainly induced by the foundation in the process of long time useage.The foundation usually has a large difference settlement in the position of the foundation soil layers with great changes and the joint with defferent foundation treatment.Especially the uneven deformation of subgrade surface will generated on the bridge/approach location and further caused serious track irregularity. There are differences of deformation form and the degree of uneven deformation between the subgrade surface and foundation surface, under the action of transfer diffusion of the embankment.CRTS II slab ballastless track was put to use in the Beijing-Shanghai highspeed railway.In order to restrain displacement of longitudinal connected slab ballastless track on the bridge caused by temperature change,the60m long anchorage system which is made of friction slab interim plate and end thorns structure et al was built on the subgrade of the bridge/approach location.The existence of the end thorns structure changes the traditional bridge/approach location basic form of flexible embankment directly connected to the rigid abutment.Developing the vibration characteristics test on CRTS II slab ballastless track bridge/approach location and mastering the vibration response of spatial change characteristics along the road longitudinal and vertical direction and the relationship between the speed of train and the vibration response have significant to improve continuity between the both ends of end thorns structure and the road and bridge structure connected position.Then refer to the research on this area both inside and outside,the experimental study were developed about the transfer behavior of high-speed railway embankment foundation differential settlement and the dynamic performance on CRTS Ⅱ slab ballastless track bridge/approach location.This paper has done some research on the following aspects.1. Transfer Behavior of Differential Settlement of Embankment Foundation Based on Centrifugal Model TestsTo study the embankment foundation differential settlement transfer behavior in the embankment and the influence mechanism on the uneven deformation of subgrade surface, firstly differential settlement of embankment foundation is respectively simplified as two kinds of models(stagger-step model and gradual change model). Through a set of own-designed and manufactured precise control equipment, which can real-time control foundation differential settlement in centrifuge operational state, carry out6centrifuge model tests, etc,the embankment height of3m,6m,9m, and foundation gradient segment length of4m,8m,12m. Focus on measuring distribution of uneven deformation along the road longitudinally, caused by the differential settlement of foundation subgrade surface. Analysis the affection to the uneven deformation of subgrade surface, including differential settlement size of embankment foundation, height of embankment, the length of gradual section of differential settlement. Test study show as follows:Uneven deformation of subgrade surface which caused by differential settlement shows "S" distribution Characteristics; the relationship between angular of uneven deformation on subgrade surface and amplitude of differential settlement in foundation is generally a linear. When there are the same angular of uneven deformation on subgrade surface, high embankment or set the gradual section on the bottom of the embankment will increase the allowed values of differential settlement on foundation. Based on the limited angular values of uneven deformation on subgrade surface, put forward the control limit of differential settlement on foundation, considering height of overlain embankment and the gradual section set on the bottom of the embankment foundation. It means a lot to the parameter system of settlement deformation control about railway subgrade.2. Long-term Field Test and Settlement Assessment Analysis of Bridge/approcah LocationCombined with the construction of the Beijing-Shanghai high-speed railway and based on sensor-networks automatic test system, long-term field tests were developed at bridge/approach location of Gaozi’east grand bridge at Beijing direction and Tianjin grand bridge at Shanghai direction. In order to conduct a statistical analysis of settlement deformation data from the abutment and adjacent subgrade,77representative bridge/approach location were selected from the settlement assessment data of Beijing-Shanghai high-speed railway JHTJ-5tenders. Test study show as follows:The settlement deformation of embankment foundation and subgrade surface at bridge/approach location are so smaller that they are all in a stable state and meet the design and control requirements, measures of foundation treatment and embankment filling have played a significant effect.The vertical differential settlement between embankment and the abutment is gradually increasing over time and tends to be stable.Extended roadbed placed time helps to reduce the differential settlement of bridge/approach location.The water content of embankment has a cyclical changed phenomenon that it is high in summer while low in winter. Season change has great influence on subgrade surface water content, with the increase of depth it tend to be stable.the height of the abutment and the depth of pile under abutment have small influence on bridge abutment settlement. With the increasing of embankment height and foundation reinforcement depth, foundation deformation at bridge/approach location tends to be a slight increase.Settlement at bridge/approach location along longitudinal from abutment to embankment is gradually increasing,The longitudinal slope of subgrade is changed at0.03‰-0.44‰, which is less than l‰the required value of deflection angle at bridge/approach location.3. Test and Analysis of Vibration Characteristics on CRTS Ⅱ Slab BallastlessTrack Bridge/approach LocationCombined with comprehensive test of the pilot section of the Beijing-Shanghai high-speed railway, the test of the vibration characteristics of the bridge/approach location under the conditions of high-speed operation of93trips has been carried out in the Sui River bridge abutment to shanghai derection. The maximum speed reached up to424km/h and dynamic response has been obtained. The vibration response of the vibration displacement, vibration velocity, vibration acceleration on the structure key parts of the both ends of the end thorns structure which adjacent to the road and bridge structure connected position were developed, and the relationship between the speed of train and the vibration response are analyzed.Test study show as follows:Along the road longitudinal direction the maximum value of vibration response is located at the junction of the end thorns structure transition board side and the subgrade bearing layer,showing that the support stiffness of the former is less than the latter; On the vertical multi-storey structure layers the vibration response is relatively large when the horizontal direction structure is discontinuity and show a decreasing trend along the depth,but the vibration characteristics is significantly improved when the track slabs are longitudinal connected; With the train speed increased the vibration displacement show a linear increase while the vibration velocity and vibration acceleration show a nonlinear accelerated increase relationship.4. Double Elastic Foundation Model Analysis Method of Ballastless Track Subgrade Mechanical Response Under Vehicle Load To study the load characteristics of the vehicle axle load through ballastless track system to the subgrade structure, The Winkler spring foundation infinite beam model and Boussinesq solution of Hooke elastic foundation are employed. Using the iterative algorithm and foundation coefficient as control condition,the stress response analysis method of double block ballastless track with vehicle axle loads is built through the use of Winkler spring foundation and Hooke elastic foundation (double elastic foundation model analysis method).Computational analysis shows that vehicle axle load has significant effects on subgrade structural stress and deformation and with the increase of axle load subgrade structural stress and deformation increase linearly.Track stiffness has a significantly influence to the subgrade surface stress and deformation. With the attenuation of track stiffness, the subgrade surface stress and deformation will increase, particularly the extreme cases when the track plate and the supporting layer fracture.Increasing the width of the supporting layer can significantly improve the force and deformation of subgrade surface, but increasing the roadbed slab width is ineffective. Changes in the formation surface thickness of the subgrade surface less impact the force and deformation. The reduction of the modulus of the foundation bed will significantly reduce the ground coefficient.更多还原