【作者】 魏道新；

【导师】 沙爱民；

【作者基本信息】 长安大学 ， 道路与铁道工程， 2010， 博士

【摘要】 无机结合料稳定类半刚性基层的应用,从根本上消除了过去石灰土基层路面常见的春融翻浆、变形等病害,大大改善了路面行驶质量和使用寿命。半刚性基层突出的优点在于能够较好地利用当地原材料,具有较高的强度和稳定性。然而伴随着经济的日益发展,公路上交通量和汽车载重量剧增,加之部分路面存在着设计上不合理,以及施工质量不高等原因,路面结构的损坏正日渐加重,路面使用品质呈逐年下降趋势,早期修建的路面已接近其使用寿命,某些新建的路面在远未达到设计年限时也出现了不同程度的损坏,公路路面出现的破损现象已不容忽视。路面病害的产生直接影响到车辆行驶的安全性和舒适性,目前对于路面病害的研究更多的投入到了路面病害的处理上,而对路面病害产生的原因、破坏机理等问题的研究较少,因此进行半刚性基层沥青路面损坏现象与损坏模式分析的研究工作是十分必要的。半刚性基层材料具有一定的适用性,针对不同的使用环境、荷载等级合理地进行半刚性基层材料组成设计和半刚性基层沥青路面结构设计,对于提高路面整体性能、延长路面使用寿命有很大意义。本文通过对具有代表性的半刚性基层沥青路面损坏情况进行详细的现场调查,系统分析了半刚性基层沥青路面的各种损坏现象；运用BISAR、PADS程序以及ANSYS有限元分析软件对半刚性基层沥青路面进行力学计算分析；考虑了基层开裂情况下半刚性基层沥青路面的力学性能；基层开裂导致模量衰减时,引入开裂度和开裂系数来表征路面结构力学性能的变化；结合对半刚性基层沥青路面力学性能的分析结果,针对寒冷、高温和多雨条件进行了研究,给出了相应情况下半刚性基层沥青路面的结构优化方案。研究认为：(1)半刚性基层沥青路面常见破坏现象有纵向裂缝、横向裂缝、龟裂、网裂、车辙、松散、坑槽、沉陷、泛油。其中裂缝类损坏是首要病害,车辙、松散等病害为次要病害。(2)半刚性基层沥青路面出现损坏的主要原因是面层和基层结构承载力不足、荷载作用、温度变化和水分入侵,次要原因是面层与基层结构和材料不均匀性。(3)力学分析表明,为使路面结构具有良好的力学性能,合理的半刚性材料厚度显得尤为重要。在半刚性基层上方铺筑沥青碎石层或级配碎石层可很大程度上改善路面的力学性能,考虑施工厚度要求,半刚性底基层厚度为20cm较为适宜。重载敏感性分析表明,沥青稳定碎石基层沥青路面的重载适应性较强,适合于现阶段我国高等级公路上重载较多的情况。(4)由于裂缝的存在,原有结构的力学性能发生改变,并且导致结构层内的应力重新分布。路面开裂且模量未衰减时,为避免进一步的破坏,当荷载不超过150KN时,基层厚度宜在30cm以上；当荷载为150-200KN时,基层厚度宜在35cm以上。路面开裂并导致模量衰减时,即使基层开裂严重,较厚的基层仍可以使路面结构保持良好的承载能力,减小基层裂缝向上反射的可能性。(5)对于多雨环境下的半刚性基层沥青路面,设置水泥稳定碎石排水基层有利于使沥青下面层和排水基层成为连续体系,延缓沥青路面出现水损坏,延长沥青路面的使用寿命。更多还原

【Abstract】 The application of binder stabilized mixture in semi-rigid has eliminated the diseases of asphalt pavement like frost boiling and deformation, also greatly improved the riding quality and service life. The advantages of semi-rigid base include:use local materials effectively, high strength and stability. But with the economy growing, road traffic and vehicle load increase rapidly, combined with some unreasonable design and construction, the damages of pavement increase badly, pavement quality decreases year by year. Many early roads close to their life time, damages occur on some new roads too. The surface damages of road cannot be ignored.Damages affect the safety and comfortableness of vehicle driving. The present study of pavement damages cost much time and energy on disposal method, but the study on damage causes and failure mechanism is still little. Semi-rigid base material has a certain applicability, in different environment and different loads, reasonably design of material composition and structure is very essential in improving the whole performance and prolong the service life.Based on the detailed field survey of damages on typical semi-rigid asphalt pavements, various damage phenomena of pavement were recognized systematically; using analysis softwares include BISAR, PADS and ANSYS, the mechanical calculation of semi-rigid base asphalt pavement was analysed; consider the mechanical properties in the case of semi-rigid base cracking; as the base cracks and modulus degrades, the degree of cracking and cracking coefficients were used to describe the mechanical properties of pavement structure; combined with the analysis of mechanical properties, the cold, heat and wet conditions were studied and the corresponding semi-rigid asphalt pavement structure optimal case were proposed.The conclusions as follows:(1) The common distresses in semi-rigid base asphalt pavement are longitudinal cracks, transverse cracks, chap, network cracks, rutting, loose, pot hole, settlement and flushing asphalt, in which cracks are the primary distresses followed by rutting, loose and so on.(2) The main reasons why semi-rigid base asphalt pavement suffers from damages are inadequate structure capacity of surface and base course, load, temperature change and moisture intrusion, and the secondary reasons are the structure and material heterogeneity of surface and base course.(3) The mechanical analysis indicates that in order to gain good mechanical properties of pavement structure, reasonable thickness of semi-rigid materials is particularly important. The mechanical properties can be greatly improved by paving asphalt-nacadam and unbound aggregate base on semi-rigid base. Consider the construction conditions, the appropriate thickness of semi-rigid sub-base is 20cm. Sensitivity analysis of heavy load shows that asphalt-treated base asphalt pavement has a strong adaptability aiming at heavy load, suitable for high-grade highways with heavy load in China at the present.(4) Due to existence of cracks, the mechanical properties of the original structure change, resulting in stress redistribution in the structure layers. When the base layer appears cracks and its modulus do not decay, in order to avoid further damage, the proper thickness of base is more than 30cm when load is under 150kN and more than 35cm when load is 150-200kN. When cracks exist and the modulus decays, the thicker base still ensure pavement structure to keep a good load capacity and reduce the possibility of reflection crack even the cracking of base is serious.(5) For the semi-rigid base asphalt pavement in rainy environment, setting cement-treated porous base will connect the bottom asphalt layer and porous base as a continuous system, which can delay emergence of water damage and prolong the service life of asphalt pavement.更多还原