【作者】 艾长发；

【导师】 邱延峻；

【作者基本信息】 西南交通大学 ， 道路与铁道工程， 2008， 博士

【摘要】 由于沥青路面完全暴露于自然环境之中,长期承受着车辆荷载的反复作用和外界自然环境的直接影响,导致路面性能衰减和破损的因素错综复杂。鉴于我国目前沥青路面结构形式还较为单一化,路面破损模式与设计指标之间存在脱节现象,以及路面材料设计体积参数与路用性能指标相关关系不明确,因此,积极开展有关考虑气候环境和交通特征、以路面使用性能为目标的沥青路面结构与材料设计方法研究具有十分重要的意义。基于此,本文以交通部西部交通建设科技项目“高原湿地郎川公路修筑及环境保护技术研究”(项目编号:200431800054)为支撑,以高寒地区沥青路面为研究对象,在广泛搜集国内外相关文献与研究成果的基础上,进行了路面破损现场实地调研,探讨了有关沥青路面结构分析基础理论问题。采用理论与实践相结合的手段,并充分考虑外界环境因素、交通荷载以及路面结构与材料的自身特性,对高寒地区沥青路面结构组成与行为特性、沥青混合料材料构成与性能特性、以及与之相适应的路面结构与材料设计方法等内容进行了较系统、深入的研究。主要研究工作和研究成果有:(1)通过对四川与西藏高寒地区部分公路沥青路面的现场调研,确定了高寒地区沥青路面的6类主导破损形式,分析了破损规律与形成机理,其中路面开裂中的温缩裂缝、反射裂缝是由于路面结构与材料自身原因而产生的最主要破损类型。(2)基于ABAQUS软件平台,深入探讨了有关沥青路面结构分析基础理论中的层间状态、车辆荷载作用方式、多因素综合作用等问题,分析了各种单因素或多因素作用对路面性能关键力学指标的影响规律。指出以接触模型分析路面的力学响应更符合路面的实际工作状态,接触模型更能体现水平荷载对路面力学行为的影响,掌握了层间状态对高、低温环境下的沥青路面行为特性的影响规律,确定了高温与车辆荷载综合作用时路面性能严重恶化的层间接触摩擦系数的临界值,给出了高寒地区特殊环境下沥青路面结构分析的力学模型与外荷载组合方式的合理建议。(3)总结了新型沥青路面结构概念及其所包含的结构类型,针对高寒低温地区的新型沥青路面结构型式,考虑沥青混凝土的感温特性,进行了基于层间接触模型的路面大温差温度行为、温度与荷载耦合行为、抗开裂行为等系统理论分析。指出全厚式结构(文中的类型三)和倒装式结构(文中的类类型五)具有更好的抗环境变化能力和抗开裂性能。由于大温差、水平与竖向荷载的联合作用,导致路面力学行为产生显著变化,与竖向荷载单独作用相比,不仅力学响应大小不同,而且响应极值出现位置也不同。(4)以AC-13酸性花岗岩沥青混凝土材料组成优化设计研究为例,充分考虑项目依托工程高寒低温和重载交通的要求,引用正交法设计思想,进行了大量室内试验,系统分析了级配类型、压实温度、成型方法、沥青用量及改善措施等因素对沥青混合料的各种性能的影响及其相关关系。以试验结果为基础,确定了项目依托工程AC-13沥青混合料的低温压实临界温度值,给出了确定各影响因素优化组合的试验方法。在此基础上,明确了高寒地区沥青混凝土材料组成设计原则与材料要求,提出了特殊环境下基于抗冻融稳定性、以体积和性能双参数作为过程控制的沥青混凝土材料组成实用优化设计方法。(5)以现场试验路实测数据为基础,系统研究了各新型沥青路面结构的温度行为特性、抗开裂性能及弯沉特点等问题。应用光纤光栅式温度传感器对高、低温季节路面温度行为的测试结果,得到了各类型路面在不同环境温度、不同时段气温、路表温度与路面内部温度场的变化规律,建立了高寒地区特殊环境下沥青路面各结构层位的分季节、分时段性的路面温度通用预估模型。应用现场开裂调查结果,描述了开裂的形态特征,评价了各新型结构的抗裂效果。应用现场弯沉测试结果,明确指出了对设计弯沉值要求过高的弊端。综合理论分析与现场试验结果,明确了高寒地区沥青路面设计原则与设计要求,推荐了高寒地区适宜沥青路面结构形式,建立了结构设计力学模型,初步提出了结构设计计算方法,提出了基于路面使用性能的分状态(高、低温状态)、分指标(应力、应变指标)的高寒地区特殊环境沥青路面结构设计与行为分析方法。更多还原

【Abstract】 Asphalt pavements exposed to adverse conditions such as application of heavy repeated vehicle loading and direct influence of external environment factors for a long period of time may exhibit unique structural behavior leading to inadequate service levels and/or premature distress. After rapid expansion of pavement construction for the last 20 years, the theory and practice of pavement engineering witnessed great achievement, especially in asphalt pavements. However, there still exist several aspects of asphalt pavements which should be addressed to advance asphalt pavement technology in China. First of all, the asphalt pavement structure types are still comparatively fixed at present and semi-rigid structural dominated design in practice. Secondly, there exist some disjoint phenomenon between the distress patterns and design indexes. Thirdly, the volumetric design parameters of asphalt mixture and pavement performance indexes are still not clear. Therefore, it is very important to study the design methods of asphalt pavement and materials based on consideration of the climate environmental factors and traffic characteristic as well to produce sound design.This dissertation reports a comprehensive research on the structure and material characteristics and their design methods in plateau-cold region. This project was supported by the Ministry of Communications’ Western Transportation Construction Research Project (NO. 200431800054).In this study the following procedures were observed: firstly, a large number of relevant domestic and international literatures and findings were reviewed and the asphalt pavement distresses were investigated on the spot. Secondly, the basic theory problems analysis was discussed. Finally, by means of combining the theory and practice and considering the external environment factors, the traffic loading, as well as the characteristics of pavement structure and highway materials, the asphalt pavement problems in plateau-cold region such as the structure type and structure characteristic, the combination of asphalt mixture and its performance, and the assumed design methods were systemically and deeply investigated. Major remarks and findings of this research are summarized as follows:(1) On the basis of the damage investigation data of asphalt pavements collected in Sichuan and Tibet Plateau-Cold Regions, the six major defects found in these regions were accurately defined, analyzed, and summarized; the law and formation mechanism for the low temperature cracking, the reflection cracking, the permanent deformation, and other defect types were studied and presented. Among these, the temperature-shrinking cracking and the reflecting cracking are the most important breaking forms owing to pavement structure and material itself.(2) The structural analysis and the basic theories of asphalt pavement structure were discussed deeply based on the software ABAQUS; the interlayer state, the mode of vehicle loading, the synthetical effects of many factors, etc, and the influencing law that one factor or many factors acted on the key mechanics were also analyzed. The results indicate that the mechanics of the contact model is more fitable for the pavement’s practical work state largely influenced by horizontal loads action. From the simulation results, the interlayer influence law of asphalt pavement characteristic at high or at low temperature was created and presented; the critical coefficient value of interlayer friction resulted in the pavement performance under the coupled action was confirmed to become worse at high temperature; some reasonable suggestions about the mechanics model and loads combination in asphalt pavement structural analysis in plateau-cold region were given out too.(3) The combinations of the concepts and new structure type of asphalt pavement are summarized in this work. Considering the temperature susceptibility of asphalt concrete based on the contact model focused on the new-type asphalt pavement in plateau-cold region, a systemic theoretical analysis such as temperature behavior with large temperature changes, coupled with temperature-loading behavior and anti-cracking behavior, were done. Results indicate that a thick asphalt pavement structure (see type 3) and hyperbatic or combined structure (see type 5) have a better performance in the cold regions and can resist to environment changes and pavement crackings. Because of the coupled action of large temperature changes on structures and vertical and horizontal loads, the pavements mechanics can behave distinctly when compared with vertical loading action; the difference existing between them consist not only on the mechanics responses but also on the position of extremum value of responses.(4)Based on the research on optimum design of acidic granite asphalt concrete material AC-13 composition, a lot of laboratory experiments were made with the method of orthogonal design and with the plateau-cold environment and the heavy traffic loads taking into account. A systemic analysis on the influence of asphalt concrete by factors such as the type of gradation, the temperature of compression, the way of compression, the Optimum Asphalt Content (OAC) and improving measures were considered. Based on the results of experiments, the low critical compression temperature and the experiment method were ensured. Furthermore, the principle and design of asphalt concrete for plateau-cold region were worked out; the optimum design method of asphalt concrete material composition based on the stability of freeze-thaw resistance and the processes control method which is composed by the parameter of volume and performance was also worked out.(5) Based on field test data, this system research has considered the temperature behavior, anti-cracking effects and anti-deflection characteristics in the design of the new asphalt pavement structures. Using FBG temperature sensor, the testing results show that the temperatures along the depth in the pavement changes dependant upon different environments and different time. A temperature forecast GM model has been established for each pavement structure in different environment and different time with different temperature. Cracking findings in the scene investigation are able to describe the cracking characteristics and evaluate the ability of the new structure’s anti-cracking effect. Deflection test results clearly point out that if the deflections are too small, it may easy lead to reflection cracking. In this dissertation, a comprehensive theoretical analysis and field test results made here may improve to better the understanding of the design principles and requests needed for plateau-cold region. Some new and suitable asphalt pavement structures have been recommended for the plateau-cold region; the mechanic model for pavment structure design also has been established. Some structure and new structural design method for the plateau-cold region based on pavement’s performance at low or high temperature conditions and different responses index (stress or strain) have been proposed in this thesis.更多还原