【作者】 王信刚；

【导师】 马保国；

【作者基本信息】 武汉理工大学 ， 建筑材料与工程， 2007， 博士

【摘要】 21世纪是开发利用地下空间的世纪，跨江海隧道和城市地铁的修建已经步入高速发展时期，其中有相当多的交通隧道是采用盾构工法来修建的盾构隧道，而钢筋混凝土管片是一种常见的应用于盾构隧道的混凝土预制构件。在跨江海盾构隧道中，管片是隧道的结构主体和防水抗渗主体，且长期处于Cl^-、SO₄^2-等有害介质的侵蚀环境下，因此，对管片的性能要求特别是耐久性要求相当高。论文研究工作来源于国家“863”计划课题（课题编号：2005AA332010）——《高抗渗长寿命大管径隧道管片材料结构设计与工程应用》，依托万里长江第一隧——武汉长江隧道工程，围绕钢筋混凝土管片耐久性技术难题进行了功能梯度混凝土管片（Functionally Gradient Concrete Segment，简称FGCS）的材料与结构设计、耐久性能、收缩性能、界面性能、制备工艺以及微观结构的研究，揭示了功能梯度混凝土管片的材料—结构—性能—工艺之间的相关规律，建立了功能梯度混凝土管片的材料与结构设计、制备工艺、性能检测、耐久性评估、工程应用等方面的关键技术。主要工作及成果如下：1、提出了功能梯度混凝土管片的设计理论体系。提出了功能梯度混凝土管片的全程性价比设计理念以及功能／结构一体化、长寿命化、界面增强等设计理论，建立了功能梯度混凝土管片的强度、耐久性、体积稳定性、多功能性、制备工艺方面的设计准则及其设计方法，为地下工程混凝土的梯度功能设计奠定了理论基础。2、完成了功能梯度混凝土管片的功能／结构一体化设计。在钢筋混凝土管片结构设计中引入梯度功能设计思路，进行功能／结构一体化设计，提出两种功能梯度混凝土管片设计方案——HPC高抗渗保护层方案和MIF高抗渗保护层方案，设计出外层高致密防水、保护层高抗渗抗蚀、结构层高强高性能和内层防火抗爆的功能梯度混凝土管片，将材料的功能设计与结构设计统一起来。3、开发了无细观界面过渡区水泥基复合材料（Meso-interfacial transition zone-free cement-based materials，简称MIF）。取消传统水泥基复合材料中粗、细集料，引入特细砂和高活性辅助胶凝材料，并掺入减缩组分、抗裂组分、憎水组分等性能调整组分，细化或消除集料—水泥石之间界面过渡区，将材料的微观结构的改善与宏观性能的优化统一起来，开发适用于地下工程结构混凝土保护层的MIF。提出MIF的设计理论，研究其力学性能、抗渗性能、抗硫酸盐侵蚀性能和收缩性能，并采用SEM-EDXA、XRD、TG-DTG、MIP、显微硬度等先进测试手段来研究其微观性能：①MIF的集料与水泥石界面过渡区显微硬度在距离集料表面10～30μm处显著增大，最低达到了395MPa，远远超出传统混凝土界面过渡区显微硬度为150～250MPa的范围，且MIF界面过渡区内的主要水化产物为C—S—H凝胶，CH晶体较少，CH晶体的取向性很不明显，因此，MIF的集料与水泥石界面过渡区由传统混凝土的60～100μm细化为30μm以下，从而有效地阻断了侵蚀性介质的渗入通道。②MIF的主要技术指标：28d抗压强度≥60MPa；Cl^-扩散系数≤0.8×10^-13m²／s，6h导电量＜300库仑，抗渗标号≥S40。4、系统研究了功能梯度混凝土的界面性能与微观结构。采用劈裂抗拉试验、自然扩散和加速扩散试验以及ANSYS模拟来分别研究功能梯度混凝土的界面力学性能、传输性能和收缩性能，同时，采用SEM-EDXA、MIP、显微硬度等先进测试方法来研究功能梯度混凝土功能层界面的水化产物及其分布、孔隙结构特征以及界面结合情况等界面微观结构，并建立其界面结构模型：①功能梯度混凝土进行两次浇注成型时，采用界面强化工艺——压印工艺可以提高功能梯度混凝土功能层的界面粘结强度10％～35％，产生界面增强效应，能够有效地解决功能梯度混凝土功能层界面粘结强度降低的问题。②与单一的高强结构层混凝土相比，高抗渗保护层与高强结构层功能梯度混凝土的Cl^-扩散系数显著下降，采用自然扩散法测试的表观Cl^-扩散系数D_a下降了25％～50％，采用NEL法测试的Cl^-扩散系数D_NEL下降了1～2个数量级，采用电量法测试的6h导电量Q低于400库仑，可见，功能梯度混凝土的抗渗性明显提高，特别是其抗离子渗透性。③以MIF高抗渗保护层方案的功能梯度混凝土管片为实例，采用ANSYS计算的功能梯度混凝土管片界面结合区的最大拉应力远小于其界面粘结强度，界面结合区由于收缩引起的应力不会引起功能梯度混凝土管片的开裂，高抗渗保护层也不会脱落，高抗渗保护层与高强结构层功能梯度混凝土界面收缩性能匹配良好。④高抗渗保护层与高强结构层功能梯度混凝土的微观结构和孔结构均得到了显著改善，与HPC高抗渗保护层方案的功能梯度混凝土相比，MIF高抗渗保护层方案的功能梯度混凝土界面结合区的显微硬度更高，界面结合区中孔半径≥25nm的孔更少，MIF高抗渗保护层方案的功能梯度混凝土从界面结合区到水泥浆体本体有较多网络状的C—S—H凝胶，以及数量较少的CH晶体，且CH晶体的取向性差，MIF高抗渗保护层方案界面结合区的结合情况要好于HPC高抗渗保护层方案的。⑤鉴于功能梯度混凝土的耐久性能和材料组分的渐变过渡，提出了功能梯度混凝土基于耐久性能变化的界面结构模型和基于材料组分变化的界面结合区结构模型；根据水泥基复合材料的集料和水泥石界面过渡区厚度和CH晶体的特点，提出了普通混凝土、MIF的集料和水泥石界面过渡区结构模型。5、建立了功能梯度混凝土管片生产与工程应用的关键技术。建立了功能梯度混凝土管片的制备工艺、压印盖板、蒸养制度、质量控制方面的关键制备技术以及性能检测技术和耐久性评估方法；实际生产的功能梯度混凝土管片的Cl^-扩散系数为4.9×10^-13m²／s，根据考虑多种因素作用下的Cl^-扩散理论模型，其预测使用寿命在280年以上。研发的功能梯度混凝土管片及无细观界面过渡区水泥基复合材料已在国家重点工程——武汉长江隧道工程上成功获得了应用。更多还原

【Abstract】 The 21 st century will be the century in which human beings will exploit the undergroundspace. The development of river-crossing tunnel, sea-crossing tunnel and urban subway hasbeen greatly accelerated. In their transportation tunnels, quit a few tunnels will be shieldtunnels which are constructed by shield method. Reinforced concrete segment is commonlya precast member used for shield tunnel engineering. Reinforced concrete segment is themain body of structure, waterproof and impermeability in river-crossing or sea-crossingshield tunnels. Furthermore, it is long-term exposed to corrosive environments of deleteriousmedium, such as chloride ion and sulfate ion. Hence, it is required that the performance ofreinforced concrete segment should be quite well, especially in durability.Funded by the Hi-tech Research and Development Program of China （863 Program） No.2005AA332010 named Material & Structure Design of High Impermeablity LongService-life Large Dimension Segment of Shield tunnel and its Engineering Application,based on the first tunnel to cross the Yangtze River named Wuhan Yangtze River TunnelEngineering, and surrounded the durability problem of reinforced concrete segment, thedesign, preparation and properties of functionally gradient concrete segment （abbr. FGCS）are presented in the paper.Based on the study of material and structure design, durability,shrinkage, interface property, preparation process and microstructure of FGCS, the relationamong material, structure, property and process of FGCS is discovered. And the keytechnologies of material and structure design, preparation process, performance detection,durability assessment and engineering applying of FGCS are established. The main researchwork and compliments are listed as follow.1. The design theoretical system of FGCS is proposed. The design concept（performance-cost ratio of the whole service-life cycle）and design theories （functional andstructural integration, long service-life and interface strengthening） of FGCS are put forward.In addition, the design principles （strength, durability, volume stability, multi-function andpreparation process） and design method of FGCS are established. Based on the abovementioned design theoretical system, the theoretical foundation for functionally gradientdesign of concrete used in underground engineerings is provided.2. The functional and structural integrated design of FGCS is accomplished. The designthought of gradient function is introduced to the structure design of reinforced concretesegment. Two design schemes of FGCS are proposed, one is the design scheme of HPC highimpermeability cover, the other is the design scheme of MIF high impermeability cover,which have high compact and waterproof outer-layer, high impermeability and corrosion-resistance cover, high strength and performance structural-layer andfire-precaution and blast-resistance inner-layer.3. Meso-interfacial transition zone-free cement-based materials （abbr. MIF） is developed.To cancel coarse aggregate and fine aggregate of traditional cement-based materials, tointroduce super-fine sand and high active supplementary cementitious materials, and toblend some ingredients modified property such as shrinkage reducing ingredient,anti-cracking ingredient, hydrophobic ingredient, etc, MIF is developed, in which interfacialtransition zone between aggregate and cement paste is reduced or eliminated. MIF is usedfor concrete cover in underground engineering structure. Meanwhile, design theory of MIF isput forward, mechanical property, impermeability, sulfate attack resistance and shrinkage ofMIF is investigated, and microstructure of MIF is analyzed through SEM-EDXA, XRD,TG-DTG, MIP and microhardness.①The microhardness of interfacial transition zone in MIF is obviously increased in 10 to 30μm distance apart from the surface of aggregate, and its value exceeds 395 MPa, while that ofordinary concrete is only 150 to 250 MPa. The main hydration product of interfacial transitionzone in MIF is CSH gel, but few is Ca（OH）₂ crystal. Besides, the orientation of Ca（OH）₂ crystalisn’t very distinct. In comparison with ordinary concrete whose thickness of interfacial transitionzone is 60 to 100μm, the thickness of interfacial transition zone of MIF is lower than 30μm.Penetration paths to corrosive medium are effectively interdicted in MIF.②MIF has several key technical indexes: compressive strength is more than 60 MPa at theage of 28 days, chloride diffusion coefficient is lower than 0.8×10^-13m²/s, Conductive chargefor 6 hours is lower than 300 coulombs, impermeability grade can be raised up to S40.4. Interface property and microstructure of FGCS is Systematically investigated. Interfacemechanical property, transport property, shrinkage of FGCS is investigated by means ofsplitting tensile test, natural diffusion method, accelerating diffusion method and ANSYSsimulation. Meanwhile, Interface microstructure of FGCS, such as interface hydrationproduct and its distribution, pore structure and its characteristic, and interface bond status,etc, is analyzed through SEM-EDXA, MIP and microhardness. In addition, interfacestructure model is discussed.①When two functional layers of functionally gradient concrete were cast, respectively,interface bond strength between two functional layers was increased by 10% to 35% bymeans of imprinting process as-compared to the control without imprinting process.Imprinting process can result in the effect of interface strengthening, and resolve the problemof interface bond strength decreasing.②In comparison with the single concrete used for high strength structural-layer, chloridediffusion coefficient of functionally gradient concrete which is made up of between concreteused for high impermeability cover and concrete used for high strength structural-layer, isobviously decreased. The apparent chloride diffusion coefficient was increased by 25% to 50% by means of natural diffusion method, the chloride diffusion coefficient was decreased by one totwo orders of magnitude by means of rapid chloride diffusivity test （NEL）, and the conductivecharge for 6 hours was lower than 400 coulombs by means of the rapid chloride permeability testmethod as designated in ASTM C1202. Thus, the impermeability of functionally gradientconcrete is obviously improved, especially, the ability to resist chloride ion penetration.③To take the FGCS with design scheme of MIF high impermeability cover as anexample, the maximum interface tensile stress due to shrinkage in interface bond zone wascalculated by ANSYS software （finite element analysis tool）, and calculation value was lessthan test value of interface splitting tensile strength. Interface tensile stress due to shrinkagein interfacial bond zone didn’t result in cracking of FGCS, and high impermeability cover ofFGCS didn’t peel off. Therefore, The compatibility of interface volume deformation was quitwell, and the sliding deformation of interface layers would not generate.④Microstructure and pore structure of functionally gradient concrete are obviouslyimproved. In comparison with interfacial bond zone of functionally gradient concrete withdesign scheme of HPC high impermeability cover, the microhardness of functionallygradient concrete with design scheme of MIF high impermeability cover was higher, and thepore whose radius is over 25 nm was much less. Furthermore, there are more CSH gel andless Ca（OH）₂ crystal. Besides, the orientation of Ca（OH）₂ crystal is more poor.⑤According to durability and materials component gradual transition of functionallygradient concrete, interface structure model base on durability chang and interface structuremodel base on materials component change were put forward. According to thecharacteristic of interfacial transition zone between aggregate and cement paste incement-based materials, such as the thickness of interfacial transition zone and the content ofCa（OH）₂ crystal and its orientation, structure models of interfacial transition zone of MIFand ordinary concrete were also put forward.5. The key technologies of production and engineering applying of FGCS are provided.The key preparation technologies （preparation process, imprinting cover board, steam-curingsystem and quality control）, performance detection technology and durability assessmentmethod of FGCS are established. FGCS is produced, whose chloride diffusion coefficient is4.9×10^-13m²/s. According to the multi-component diffusion equation, a service life of 280years for FGCS is predicted. Furthermore, FGCS and MIF were successfully applied toWuhan Yangtze River Tunnel Engineering.更多还原