【作者】 刘丽；

【导师】 郝培文；

【作者基本信息】 长安大学 ， 道路与铁道工程， 2008， 博士

【摘要】 层间结合优劣是影响沥青路面使用寿命的重要因素之一，若层间结合不好，就会破坏路面结构的整体性，削弱路面结构的整体抗力，在车辆加速、减速的地方易发生层间剪切滑移，产生月芽形推挤裂纹。为了使路面多层组合体系具有良好的结构承载力和耐久性，应该加强沥青路面层间处治技术的研究。本文在调查沥青路面层间处治技术现状基础上，通过分析不同层间接触状况下的沥青路面受力，揭示了U形开裂的机理，分析了层间接触状况对沥青路面路用性能的影响。然后围绕粘层、封层和透层材料展开系统室内试验，通过直接剪切和直接拉拔试验对层间结构强度进行了深入研究，目的是分析层间强度的影响因素及其各个因素影响的显著性，以及测试方法的可行性和评价指标的合理性，为相关技术规范的修订提供依据。同时，对沥青路面层间剪切疲劳性能进行了研究，初步探讨了层间疲劳破坏的机理，提出了描述层间强度破坏的剪切模型和参数。最后，在力学分析和试验研究的基础上，提出了考虑抗剪强度的沥青路面结构设计方法。具体研究内容如下：(1)采用有限元分析软件ABAQUS，以半刚性基层沥青路面为研究对象，把试验参数应用到力学分析模型里面，研究水平荷载、层间接触条件和超载对沥青路面力学响应的影响以及分析U形开裂产生的原因。结果表明，水平荷载对路面应力场的分布有很大影响，尤其是对路面上面层的影响不可忽视；车辆超载和基面层间的不连续会加剧沥青路面的车辙，纵向滑移的产生主要是由超载和面层层间的不连续引起的，对路表弯沉影响最大的是荷载，其次是基面层间接触状况，最后是面层层间接触状况；U形底部开裂是拉应力导致的张开型裂缝，U形的两侧开裂是竖向剪应力导致的剪切型裂缝，面层层间的连续与否和水平荷载的作用对U形开裂产生的影响最为显著。(2)采用三种粘层材料——乳化沥青、改性乳化沥青和普通热沥青，对粘层油用量、粘层油种类、温度、层间界面清洁程度、浸水、冻融、行车荷载的作用、上下面层沥青混合料的级配类型等影向因素展开研究，并对每个影响因素进行方差分析。同时，从高温性能和耐久性能出发，研究不同接触条件对沥青路面路用性能的影响。结果表明，高温时确定的最佳用量比常温下小0．1-0．2kg/m~2；喷洒粘层油有利于提高层间抗剪切性能、沥青路面的高温稳定性能和耐久性能以及减轻层间污染、浸水、冻融对层间产生的不利影响。最后，综合粘层抗剪性能和透水性能，推荐了适合不同气候的粘层材料和喷洒量；在力学计算和试验研究的基础上，提出了沥青路面粘层结构抗剪性能的评价方法、评价指标和技术要求。(3)对同步碎石封层技术研究了各种影响因素对层间抗剪强度的影响程度，并将同步碎石封层与稀浆封层抗剪强度和层间透水性能进行比较。研究结果表明，沥青材料性质、集料岩性、集料的不同处理方式、沥青和集料撒布的同步与否对同步碎石封层抗剪强度产生了显著性影响，集料粒径大小对其产生一定程度的影响，但是影响不显著；作为下封层使用时，稀浆封层抗剪强度小于同步碎石封层的抗剪强度，但其防水性能明显优于同步碎石封层。最后，根据降雨量和面层类型推荐了合适的下封层材料。(4)采用三种透层材料——稀释沥青、乳化沥青和改性乳化沥青以及两种常见的半刚性基层类型——水泥稳定碎石基层和二灰稳定碎石基层进行研究，研究不同稀释率、不同种类透层材料的渗透性能以及基层类型、基层养生龄期对透层材料渗透性能的影响。研究结果表明，稀释沥青的渗透效果要远远优于乳化沥青，改性乳化沥青不适合作为透层油使用；相同喷洒量下，透层油在水泥稳定碎石基层上的渗透深度大于在二灰稳定碎石基层上的渗透深度，且二灰稳定碎石基层比水泥稳定碎石基层的喷洒用量要小；透层油的喷洒时机宜早不宜迟。最后，推荐出适合不同基层类型的透层材料。(5)通过自行研发的剪切试验，对沥青路面进行了层间剪切疲劳试验，研究有无粘层油、粘层材料种类和层间污染对疲劳性能的影响。通过分析，提出了层间剪切疲劳性能的评价方法和评价指标以及层间剪切简化模型，进行了剪切疲劳破坏机理分析，在此基础上，进一步提出了层间结合状态衰变的简单模型。(6)根据我国不同地区的气候特点，同时结合层间材料的路用性能要求，将七月平均最高气温和降雨量作为我国沥青路面层间材料的气候区划指标，提出了我国沥青路面层间材料的气候区划。并且，在力学分析和试验研究的基础上，提出了层间容许剪应力的计算方法和考虑抗剪强度的沥青路面结构设计方法。更多还原

【Abstract】 The quality of layer interfaces is one of the important factors that influence the life of the asphalt pavement. A poor bond between pavement layers destroys the unity of pavement structure and reduces its bearing capacity. Slippage failure often occurring at the places where vehicles accelerate or decelerate, is the most commonly observed problem related to poor bond between layers. The typical distress is described as crescent cracking. In order to achieve the desired bearing capacity and a longer lifetime of a pavement structure, the research on the technology of adhesion at the interface between asphalt pavement layers is of great significance.Based on the current technology of asphalt pavement layer interfaces, the paper analyzed the mechanical response of pavement structure with different bond conditions between pavement layers. The results showed the mechanism of U-shaped cracking and evaluated the influence of different bond conditions between pavement layers on asphalt pavement performance. Then through comprehensive laboratory experiments, this paper mainly studied the properties of the tack coat, seal coat, prime coat in the asphalt pavement structure. The bond strength of the interfaces was systematically evaluated by direct shear test and direct pull-off test, aiming to analyze the influence of several factors on the adhesive bond at the interface between pavement layers. Each statistically significant level was also tested in this paper. The feasibility of test methods and the reasonableness of evaluation indexes were validated through laboratory experiments, so as to provide a basis for revising related technical specification. At the same time, the shear fatigue properties at the interface of asphalt pavement layers were studied. The discussion about fatigue failure mechanism of the interfaces was conducted. A model was put forward and three parameters were selected to characterize shear fatigue failure at the interface. Finally, on the base of mechanical analysis and testing research, the design method of the asphalt pavement, considering shear-resisting strength, was put forward.The details of the research can be described as follows:(1) For the semi-rigid base asphalt pavement, by inputting the test parameters into a finite element program (ABAQUS), the paper studied the influences of horizontal loads, bond conditions between pavement layers and overloading of vehicles on the pavement structure mechanical response and analyzed the causes of the U-shaped cracking. The results showed that horizontal loads had a significant influence on stress distribution of pavement structure, especially for top surface layer. The vehicle overloads and the discontinuation between the surface and the base exacerbated the rut of the asphalt pavement. For the longitudinal slipping, its occurring was mainly caused by overloading of vehicles, and then by the discontinuation between the surface layers. For the deflection, the greatest effect factor was the load, the next was the bond condition between the surface and base layers, and the last one was the bond condition between the surface layers. The bottom of U-shaped cracking was open tension-type cracking led by tensile stress while the both sides of U-shaped cracking were shear-type cracking led by vertical shear stress. The continuity of surface course interlayer and horizontal loads had a great effect on the development of U-shaped cracking.(2) This paper investigated the influence of several factors on the adhesive bond provided by the tack coat at the interface between pavement layers. These factors included application rate, tack coat type, testing temperature, the surface cleanliness, moisture, sudden change of environment, traffic and mixture type. The statistical significance of the differences in interface bond strength was evaluated. Emulsified asphalt, the polymer modified emulsion asphalt and hot asphalt binder were selected as the tack coat materials. At the same time, the influence of different bond conditions between pavement layers on pavement high temperature performance and durability was evaluated. The results showed that the optimum application at the test temperature of 60℃was 0.1～0.2kg/m~2 less than the application at that of 25℃Tack coat was good for improving interlayer shear performance, high-temperature stability and durablity of the asphalt pavement, and reducing the unfavorable effect of interlayer pollution, rain and environment change. Lastly, this paper recomended suitable tack coat materials and application rates for different climate conditions. On the base of mechanical analysis and testing research, the evaluation method, evaluation index and the technical requirements for the anti-shearing performance of asphalt pavement structure were put forward.(3) For the technology of synchronous surface dressing, the effect factors of the interface shear strength were examined and the statistical significance of the differences in interface shear strength was evaluated. The comparison on the interface shear strength and permeability between synchronous surface dressing and slurry seal was made. The results showed that asphalt properties, aggregate lithological composition, processing mode, and the asphalt binder and aggregate spreading synchronization provided a significantly better bond at the interface between the pavement layers, while the aggregate particles size did not significantly affect the bond strength at the interlayer. As seal course use, the shearing strength of slurry seal was smaller than that of the synchronous surface dressing, but its waterproof performance was obviously better than that of the synchronous surface. Lastly, the paper recommended the suitable seal coat materials for different rainfall and mixture types.(4) The experiment included three types of prime coat materials (cutback, emulsified asphalt and the polymer modified emulsion asphalt) and two types of semi-rigid base materials (cement stabilized granular base and lime-flyash stabilized granular base). The influence of different dilution ratio, prime coat type, base type and curing time of semi-rigid base on penetrability was evaluated. The results showed that the permeability of the cutback asphalt was far better than that of the emulsion asphalt while the polymer modified emulsion asphalt was unsuitable to be used as the prime coat. At the same application rate, the penetrability of prime coat on the cement stabilized granular base was better than lime-flyash stabilized granular base, and the application rate on the lime-flyash stabilized granular base was smaller than on the cement stabilized granular base. The spraying occasion of the prime coat was good for early. Lastly, the paper recommended the suitable prime coat materials for different bases.(5) A shearing test method was developed to conduct the interlayer shearing-fatigue test. The paper studied the effects of existence of tack coat, tack coat type and the surface cleanliness on the shear fatigue property. By analysis, the paper put forward evaluating method, evaluating indexes and a simple shear mechanical model for interlayer to assess the shear fatigue properties of the interlayer between the pavement layers. Based on the analysis of the mechanism of shear fatigue failure, a simple performance declination model for interface was put forward.(6) According to the climatic characteristics of our country and the performance requirements of interlayer materials, the average highest temperature in July and rainfall were selected as the climatic zoning indexes of asphalt pavement interlayer materials. Based on mechanical analysis and testing research, the paper put forward a calculation method of interlayer allowable shear stress and the design method of asphalt pavement considering shear strength.更多还原