【作者】 吴国雄；

【导师】 姚令侃；

【作者基本信息】 西南交通大学 ， 道路与铁道工程， 2003， 博士

【摘要】 水泥混凝土路面作为一种高级路面结构形式，以其强度高、稳定性和耐久性好、耐高温、耐磨耗以及养护费用少等优点而得到了广泛的应用。按照现行路面设计理论，路面结构各层性能正常、层间界面接触理想、设计和施工质量良好的水泥混凝土路面，一般要经过长期使用且达到其设计使用年限后才会开裂破坏。但实际状况是，相当多的路面在使用2-5年甚至更短时间后就出现了不同程度的缺陷或开裂。同时，水泥混凝土路面的维修成本高，养生时间长，维修期间交通干扰严重，一旦破坏就很难修复。因而，认清水泥混凝土路面的开裂机理和破坏过程，提高其抗裂性能，是当今工程界迫切需要解决的问题。 为此，本文在已有研究成果的基础上通过广泛调研，结合作者近几年来主持或参加的有关水泥混凝土路面研究课题的部分成果，在路面基层的各种性能得到保障的前提下，通过理论研究和试验研究，得出路面板的开裂破坏过程分为三个阶段，即初始裂缝形成阶段、裂缝累积和扩展阶段以及路面断裂破坏阶段。同时，将路面开裂的影响因素由下而上分为三个不同的层面，即：路面板底层——路面与基层界面之间过渡层的形成及其开裂，是导致初始裂缝形成和影响后期开裂的根本原因；中间层——路面板体。在荷载作用下，使得已经存在初始裂纹和固有损伤条件的路面板，其裂缝和损伤进一步累积和拓展，为路面的断裂破坏奠定了基础；表面层——由于路面表面的不平整而引起的车板相互作用带来车辆运动荷载的冲击，是加速路面板断裂的主要原因。同时，通过试验论证，提出相应的减少路面开裂破坏的有关技术措施。最后，考虑到路面开裂和破坏的复杂性和非线性，本文采用非线性科学理论(如混沌、分形等)来解释路面裂缝生成和扩展的机理和过程，从总体上对开裂和破坏的全过程加以描述，为水泥混凝土路面的开裂机理和破坏过程研究提供一种新的思路和方法。 本文的创新点主要表现在以下几个方面： 1．通过对路面板底界面开裂、路面板中裂缝积聚、扩展和路面表面车板相互作用及其对路面疲劳破坏的影响等三个层面的研究和分析，首次提出水泥混凝土路面的开裂和破坏过程可以分为三个阶段，即路面板底初始损伤 西南交通大学博士研究生学位论文第11页和早期裂缝的形成阶段、使用期间荷载作用对路面造成的开裂损伤累计、加剧和裂缝扩展阶段以及路面断裂破坏阶段。 2.提出了路面板与基层之间的层间结合关系和六种结合模式，并根据断裂力学的基本原理提出了路面板在早期凝结过程中，在面层与基层之间形成薄弱过渡层。由于路面板的早期收缩产生的应力大于其强度，并且路面板的进一步收缩以及这种收缩受到路面板自重以及基层的限制，使过渡层断开、开裂和破坏，导致路面板底形成了初始的损伤和裂缝。通过理论分析和试验研究得出，这种早期裂缝和损伤的形成，.是加速路面后期裂缝扩展和疲劳破坏的基本原因。 3.综合利用损伤力学和断裂力学的基本原理分析提出，水泥混凝土路面板早期凝固过程中形成大量的微小缺陷而构成初始的损伤场，在荷载作用下，会导致路面板发生不均匀的损伤，板底裂缝尖端附近区域成为损伤最严重、开裂韧度下降最快的部位。随着荷载作用次数的增加，板底裂缝尖端附近区域的损伤度不断增大，韧度逐渐降低。当板底裂缝尖端造成的应力强度因子大于裂缝尖端附近区域的开裂韧度时，裂缝开始扩展，路面中性轴逐渐上移。裂缝尖端向上移动到达新的位置后，新的附近区域又以较高的韧度阻止裂缝继续扩展，于是开始新一轮的损伤累积。这样，裂缝尖端的不断移动和尖端附近区域的损伤累积两个过程交替进行，使路面板底裂缝不断向上扩展。一旦荷载在裂缝尖端造成的应力强度因子大于混凝土路面失稳时的开裂韧度，裂缝迅速扩展而贯穿整个路面厚度，使板块断裂。水泥混凝土路面正是遵循这样的机理和过程完成其整个开裂和破坏的。 4.在已有理论分析的基础上，通过试验研究验证了由于路面不平整引起的车板相互作用产生的动态响应与路面表面平整状况、车速之间的关系，并分析计算了这种动态响应对路面疲劳破坏产生的严重影响，从另一角度解释了水泥混凝土路面往往在低应力水平状态下远未达到设计使用年限即出现破坏的真正原因。 5.通过理论和试验研究，进一步定量分析和验证了荷载作用下路面裂缝的扩展过程可以用混沌方程、分形理论和渗流模型等非线性理论加以描述。用混沌方程的迭代次数描述荷载的次数，用稳定态描述路面无损伤状态，用分叉态描述路面损伤积累状态，用混沌态描述路面裂缝扩展状态;用荷载作用下混凝土路面内部裂缝分维数的变化描述混凝土路面在各种应力水平 西南交通大学博士研究生学位论文第川页作用下的开裂损伤状况，用混凝土路面在疲劳荷载作用下不同阶段开裂区裂缝分布的分维数的变化及其趋势来描述路面破坏的阶段和进程;用渗流阀值来表征混凝土路面的临界破坏条件。 6.在上述分析研究的基础上，针对性地提出了处理路面板与基层的层间界面?更多还原

【Abstract】 The cement concrete pavement, as one of the high-grade pavement structures, has been widely used because of such advantages as high strength, good stability, great durability, high temperature stability, abrasive hardness and low cost of maintenance. In line with the theories of the present pavement designs, the cement concrete pavement, with normal performance in the structure of every layer, ideal interlayer contact as well as good designs and construction, will usually not break until a long time of use or the time designed. But actually, quite a number of such pavements show defects or crackles of varying degrees within 2-5 years or shorter. Meanwhile, owing to its features such as high cost for maintenance, severe traffic interference during maintenance, and difficulty in maintenance of what is damaged, it is a problem deserving immediate solution in present-day projects to know the fissure mechanism and breaking process of the cement concrete and improve its anti-fissure performance.Therefore, the present paper, based on the existing achievements as well as an extensive study & investigation in combination with part of the achievements the author has derived by hosting or participating in the research programs of the cement concrete pavement, has led to three phases of fissures and breaking in the pavement slab on the condition that each performance of the subgrade is maintained, i.e. stages of formation in initial cracks, of accumulation & expansion in ruptures and of fissures & breakage in the pavement. Meanwhile, the factors causing fissures in the pavement fall into three layers from down to up,namely, the bottom layer of the pavement slab-the formation and fissures &breakage of the transition layer between the pavement and base interface makes the chief reason for the formation of initial cracks and later fissures; the middle layer-the pavement plate. The pavement panel, under load and with already existing initial cracking & inherent damaged conditions as well as its cracks & damage, further accumulates and expanses, which lays a foundation for the fissures & breakage; the surface layer- as the uneven pavement brings aboutinteraction between spring plates which results in impact on the vehicle load, is the main reason speeding up the fissures in the pavement panel. And through the evidence of tests, the paper brings forward some technically relevant measures to reduce fissures and breakage in the pavement panel. Finally, in view of the complexity and non-linearity of the pavement in cracking and breakage, the paper tries to explain the formation in the cracks of the pavement and mechanism & process of expansion by nonlinear theories (like chaos , fractal etc.) and to describe the whole process of fissures and breakage so as to provide a new thought and method for the study of the cement concrete.. What is shown in the paper is of great theoretical and practical significance to the perfection of theories in pavement designs and construction methods, to the eradication or reduction of hidden risks in the pavement as evidence for the research of new anti-fissure materials in the pavement, new technology and new techniques. The paper has a few creative points to recommend as follows:1. Through the research and analysis on the three aspects concerning the base interface of the pavement panel, crack accumulation, expansion in the pavement panel and interaction between spring plates on the road surface as well as its damage on the road fatigue, it is first brought forth that the process of fissures and breakage in the cement concrete pavement can be divided into three stages, i.e. stage of initial crack formation and damage in the bottom of the pavement slab, stage of accumulation, intensifying & expansion in ruptures from load during the time of use and stage of fissures & breakage in the pavement.2. Aiming at the binding relationship between the pavement and the base, the author, by collaborating with related research groups, bring forth for the first time the formation of a weak tran更多还原