【作者】 白皓；

【导师】 苏谦；

【作者基本信息】 西南交通大学 ， 道路与铁道工程， 2013， 博士

【摘要】 布设支挡结构是陡坡路基边坡工程的常见技术措施。随着工程人员对陡坡路基支挡结构破坏机理的深入研究,国内外针对山区陡坡路基支挡工程病害的研究和防治工作空前活跃,支挡结构型式也在完善已有措施的基础上向结构化、组合化和经济性、环保性方向发展。组合式抗滑支挡结构正是在这种国内外形势下重新出现在科技工作者的视野之中,新提出的椅式桩板墙就是其中最具代表性的结构型式之一。铁路行业早在上世纪70年代开始应用类似的支挡结构,但是由于其理论研究远远落后于工程应用,迄今为止还没有成熟的研究成果,设计、规范和手册上也没有相关条款,严重制约了这类支挡结构的发展与推广本文依托中国中铁科股份有限公司科技研究开发计划课题《无砟轨道陡坡路基椅式桩板结构研究》、中铁二院工程集团有限责任公司科研项目《叙大铁路龙山车站高路堤椅式桩板墙应用研究》与道路工程四川省重点实验室开放研究基金课题《陡坡椅式桩板结构路基设计分析理论》等课题开展研究。对支挡路基边坡的椅式桩板墙的定义、分类与研究现状进行了介绍,论述了椅式桩板墙在岩质和土质边坡上的工作机理。分别进行了岩质边坡和土质边坡椅式桩板墙室内大比例模型试验,分析了不同技术工况下椅式桩板墙的变形受力机理及破坏特征,研制了适用于室内模型试验的微型应变式油压土压力计。对岩质边坡和土质边坡上椅式桩板墙的内力变形进行了数值仿真,讨论了重要结构型式、关键设计参数、岩土体参数等对结构内力变形的影响性。在结构设计计算中,将承载板与挡土板简化为简支梁构件进行设计,将椅式桩简化为平面结构,采用弹性地基梁法和结构力学位移法两种方法计算结构内力与变形。最后,利用理论计算方法对关键参数进行分析与讨论,并提出椅式桩板墙的设计方法。针对椅式桩板墙的研究成果,本文主要得出以下结论：1.定义路基边坡工程中新型的椅式桩板墙为组合式抗滑支挡结构,其由椅式桩、承载板和挡土板组成,综合了埋入式连续桩板结构、悬臂式桩板墙与双排抗滑桩的技术特点,兼有支挡、阻滑和承重三重功能,可以按照其布设位置、组合形式和受荷类型进行分类。2.承载板和横梁支承竖向荷载,使椅式桩板墙的重心后移,提高了其抗变形能力与整体稳定性；椅式桩板墙具有抗变形能力强、耐久性好、收坡快、占地范围较小等优点,适用于斜坡高填方路堤、深大路堑、深厚软弱土斜坡、大型滑坡体、山区陡坡、山区城市道路等复杂条件下的路基边坡支挡工程。3.当位于岩质陡坡上时,竖向荷载通过承载板作用于椅式桩上,主副桩通过横梁连接共同抵抗横向荷载,主要表现出承重和支挡双重功能,当岩体中存在节理面或软弱带时,椅式桩又体现出抗剪阻滑的特性。当位于土质边坡上时,部分荷载和滑坡推力还会通过坡体中的土拱效应传递给椅式桩,此时主要表现出阻滑与支挡双重功能。4.当岩体完整性较好时,桩侧岩石压力可按理论计算、经验方法或弹性抗力法求解；当岩体存在外倾结构面时,需确定最不利工况下的岩石压力；类土质岩石边坡可按土质边坡考虑。土质边坡上主动力按经典土压力理论、土拱理论或滑坡推力中较大者确定,被动力按经典土压力理论、弹性地基梁法或剩余抗滑力中较小者确定；滑坡推力与剩余抗滑力的计算往往较为繁琐,可采用修正后的土压力进行代替。5.内力协调机制使椅式桩上出现多个反弯点,大幅降低了结构内力；椅式桩破坏模式一般为某构件形成塑性铰使结构丧失正常使用功能,在可预见的较大荷载作用下椅式桩板墙不会发生倾倒破坏。6.副桩布设于主桩内侧可有效降低椅式桩内力、转换桩基拉压属性,桩梁刚度比控制在1-3范围内,可有效保证椅式桩的荷载效应自我调节作用；椅式桩纵向桩间距一般取3-5倍的桩径或桩宽、数值范围取5～8m,椅式桩横向桩间距一般取2.5～4倍的桩径或桩宽；岩质边坡坡角在40°～70°范围内时,主桩最优悬臂系数取值为0.4～0.6。7.在结构设计计算过程中,当不考虑结构扭转变形时,可以将椅式桩简化为竖向和侧向联合受力的平面结构,根据桩顶与桩底的约束条件和各构件之间、各典型受荷区段之间的内力、变形连续条件,采用弹性地基梁法或结构力学位移法求解结构的内力和变形,并提出了不同计算方法的适用条件。更多还原

【Abstract】 Retaining structure is an indispensable mechanical control measure on steep embankment slope. With intensive studies on the failure mechanism of retaining structures, researches about disasters prevention are unprecedented active at home and abroad. Based on existing structure styles, a develop tendency of integral, combinational, economical and environmental has occurred. Among all the new retaining structures that have come into the sight of researchers, the Chair-Shaped Pile-Sheet Retaining Wall is the most representative one. The application of similar structures on railway industry began in early1970s. However, theoretical study of these structures has always been far behind engineering application, with no mature design codes available, which is seriously restricting the development and promotion of this type of retaining structure.Relying on following projects, such as "Research on the Chair-Shaped Pile-Board Structure of the steep embankment on the unballasted track railway" of the research and development of science and technology plan project of China Railway Group Limited,"Research on the Application of the Chair-Shaped Pile-Sheet Retaining Wall on the Long Mountain Station of the Xuyong-Dacun Railway " of China Railway Eryuan Engineering Group CO.LTD, and "The Analysis and Design of the Chair-Shaped Pile-Board Structure on the Theory" supported by the open research fund of Key Laboratory of Highway Engineering of Sichuan Province, Southwest Jiaotong University, the paper conducted the research, introduced the definition, classification and research status and the working mechanism on rock and soil slopes of the Chair-Shaped Pile-Sheet Retaining Wall. We carried on the studies of the large scale model test of the Chair-Shaped Pile-Sheet Retaining Wall on both rock slope and soil slope respectively, analyzed the mechanism of deformation and stress and failure characteristics on rock slope and soil slopes under different technical conditions, developed the micro strain type hydraulic pressure gauge suitable for indoor model test. In structure design and calculation, the loading plate and soil retaining plate are simplified to simply supported beam, the chair-shaped pile is simplified to flat structure, the displacement of elastic foundation beam method and the structural mechanics method are adopted to calculate the structure internal force and deformation. Finally, the design cycle of Chair-Shaped Pile-Sheet Retaining Wall is put forward by using theoretical calculation method to analyze and discuss the key parameters. Some conclusions are drawn below.1. The paper defines the new type of the Chair-Shaped Pile-Sheet Retaining Wall as a composite anti-sliding retaining structure, consisted of chair-shaped pile, the bearing plate and soil retaining plate, which combines the technical characteristics of the Embedded Continuous Pile-Board Structure, Cantilever Sheet Pile Wall and Double-Row Anti-Slide Pile. It has the triple functions of retaining, anti-sliding and bearing, and could be classified according to the layout position, combination form and load types.2. When the bearing plate and beam support vertical load, the gravity center of Chair-Shaped Pile-Sheet Retaining Wall would move behind, which enhances its ability to resist deformation and overall stability and has a unloading effect to the main pile. Chair-Shaped Pile-Sheet Retaining Wall has following advantages, such as good anti deformation ability, good durability, fast slope withdrawing and covering small area etc. It is applied to following complex conditions of subgrade slope retaining engineering, such as high fill embankment, deep cutting, deep slope of soft soil, large landslide, and steep slope and city road in mountain area.3. When the Chair-Shaped Pile-Sheet Retaining Wall is located on rock slopes, the vertical loads pass through the bearing plate and distribute on the chair-shaped piles. Since the deputy piles are connected through a beam to resist lateral loads, the structure performs both bearing and retaining functions. When joint plane or weakness appears in the rock, the chair-shaped pile reflects the merits of slide resistance. When the Chair-Shaped Pile-Sheet Retaining Wall is located on soil slopes, partial loads and landslide thrust are transmitted to the chair-shaped pile due to the soil arch effect in the slope. Under this condition, the structure shows both resistance and retaining effects.4. When the rock integrity is better, rock pressure acting on the pile is calculated according to the theoretical calculation method, experience or elastic resistance method. When the rock structural plane is extraverted, the most unfavorable conditions of rock pressure needs to be determined. Soil similar slope can be considered as soil slopes. Active earth pressure on soil slopes is determined by maximum value of the classical earth pressure theory, the soil arch theory or the landslide thrust. Passive earth pressure is determined by minimum value of the classical earth pressure theory and elastic foundation beam method or residual sliding resistance. Because the calculation of the landslide thrust and residual sliding resistance is relatively cumbersome, rock pressure acting on the pile can be determined by the revised earth pressure.5. Internal coordination mechanism induces multiple inflection points on the chair-shaped pile, which greatly reduces the structure internal force. Chair-shaped pile failure mode is generally that one of the components generating plastic hinges which results in losing of structure’s normal function. But chair-shaped pile-sheet retaining wall won’t occur capsizing failure under excessively large loads.6. When deputy pile is arranged on the main pile side, it can effectively reduce the internal force of chair-shaped pile, and converse compressive and tensile property of pile. It can be effectively guaranteed that the self-regulatory role of chair-shaped pile’s load by controlling stiffness ratio of pile and beam among1to3. The chair-shaped pile’s vertical pile spacing is general3to5times of the pile diameter or width, or5m to8m, the lateral pile spacing is general2.5to4times of the pile diameter or width, and the value of optimal cantilever coefficient of main pile is0.4to0.6.7. The chair-shaped pile is simplified as a vertical and lateral jointly stressed planar-structure without considering the structure deformation in the process of structural design calculation. According to the constraint conditions between pile top and pile bottom as well as the internal force and continuous deformation conditions among each members and the typical internal segments, the mechanics and deformation of the structure are calculated by using elastic foundation beam method or displacement method in structural mechanics, and the applicability of different calculation methods is put forward.更多还原