【作者】 袁宏伟；

【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】 作为国民经济大动脉,公路的行车舒适性、使用寿命、抗重轴载的破坏能力等使用性能是工程建设的重心,其中对行车质量的保持程度,尤为公路使用者和建设者的关注热点。而这些性能的实现无疑与基层这一主要的受力层和结构转换层息息相关。路用性能优越的基层,将提高整个公路的使用质量和运营寿命。为深入了解柔性、半刚性、刚性三种不同类型的基层对沥青路面使用性能的影响,提出与气候和交通等条件相适应的基层材料结构,本项目在山西省大新高速公路铺筑了实体工程,该试验路段囊括了国内外高等级公路上常见且较合理的基层结构类型,包括4种沥青路面面层厚度结构组合,4种混合料级配类型,4种改性沥青,7种基层结构组合和2种复合式路面结构,总计22种沥青路面结构总长7公里,其在国内沥青路面性能研究中属首次。本文依托实体工程,针对目前公路沥青路面常用的柔性基层、刚性基层、半刚性基层等三类基层类型的材料设计与路用性能展开室内试验研究与实体工程现场施工与性能检测验证。采用正交敏感分析方法,结合BISAR程序计算结果,深入分析了基层力学设计参数；结合试验路的铺筑,对三类基层的施工技术进行比较研究,并对试验路的弯沉和裂缝进行了长期的跟踪检测,对试验路裂缝问题进行成因分析并提出有效的处治措施；运用寿命周期费用分析法分析了基层设计对沥青路面建设费用的影响。研究认为：(1)柔性基层材料组成设计时,采用马歇尔击实成型下的力学指标法能够取得良好的设计效果。采用大马歇尔击实成型条件下,ATB-30级配的力学指标法能够获得良好的低温抗裂性能,并且疲劳性能和高温抗变形性能也较好；ATB-25级配的力学指标法能够同时获得良好的高低温抗变形和疲劳特性；AC-30Ⅱ级配的力学指标法也能够同时获得良好的高低温抗变形和耐疲劳特性；AM-30级配的传统马歇尔法能够获得良好的低温抗裂性能。ATB-30表现出较其他几种类型级配更为优越的高温抗变形、低温抗裂和耐疲劳性能。(2)对比贫混凝土、高掺量粉煤灰混凝土基层两种刚性基层的配合比设计、强度、刚度等特性得出：随着粉煤灰含量的增加,水泥含量的减少,抗压强度和抗折强度都逐渐减小,且减小趋势逐渐变缓。粉煤灰在混凝土中起着微集料效应、火山灰效应和滚珠效应,粉煤灰、水泥、集料的不同比例及龄期的变化影响着该类材料的力学特性。(3)水泥稳定基层材料的抗压强度>抗折强度,抗压弹性模量>抗折弹性模量,随着龄期的增长,水泥稳定基层材料的强度和模量均逐渐增大。抗压强度随龄期变化规律的线性回归结果：抗压强度Rc=0.0549 T(龄期)+3.5782,R2=0.999,抗压强度随龄期的变化速率前期和后期相差较小。(4)路面结构设计中关键因素的正交敏感分析表明,各结构因素的敏感性大小排列为：基层厚度>底基层模量>基层模量；路面承载力计算结果表明,路面承载能力大小排列为刚性基层>半刚性基层>柔性基层。(5)柔性基层的施工中施工厚度、温度的选择和防止离析是关键,施工厚度可以加大到粒径的5倍以上,压实温度的控制宜采用粘温曲线确定的温度进行,在温度降低到80℃以前完成碾压成型；刚性基层施工时整平难度较大,可通过添加外掺剂来改善施工性能；半刚性基层的施工过程中,应注意控制含水量和水泥等胶凝材料的用量,以减少半刚性基层裂缝的产生。(6)实体工程沥青路面裂缝的分布密度排列为：柔性基层<半刚性基层<刚性基层,裂缝的宽度密度排列为：柔性基层<半刚性基层<刚性基层,最大裂缝宽度排列为：柔性基层<半刚性基层<刚性基层。裂缝处钻芯取样结果表明,裂缝主要为基层反射裂缝,降温速度快和温度过低是导致基层开裂产生路面反射裂缝从而使试验路出现裂缝的主要原因。(7)不同基层类型沥青路面的寿命周期费用分析经济评价结果表明,柔性基层较一般半刚性基层沥青路面使用寿命长,能在较长时间内保持较高的服务能力,相对减少行程时间费、车辆运行费和事故费。(8)在选择基层类型时,要深入分析刚性、柔性、半刚性基层各自的特点,结合当地的交通量大小、气候条件、水温地质条件,在保证基层满足基本路用性能的前提下,着重考虑主要性能要求,同时兼顾次要性能要求,经济合理地选用可获得最大路用效益的基层。研究成果有助于提高我国公路工程技术水平和公路工程建设质量,可为相关规范的修订提供参考。更多还原

【Abstract】 As the aorta of the national economy, the highway attracts much attention, its performances such as drive comfort, service life and anti-heavy-duty capacity, especially the maintenance of riding quality. And all these performances are closely linked with the roadbase, which is the main stress layer and structural conversion layer. Base layer with excellent performance will improve the operating quality and extend the service life of highway.In order to study the impact from flexible base, semi-rigid base and rigid base on the performances of asphalt pavement, and propose the reasonable structure fits the climate condition and transportation condition, Test road with usual and rational base structures at home and abroad was paved in Datong-Xin guangwu expressway in Shanxi Province. The test road includes four pavement structure combinations, four gradation types, four types of modified asphalt, seven base layer structure combinations and two kinds of composite pavement structures, has 22 pavement structure types and a total length of 7km. Both pavement structure types and total length are the firth time in china,Relying on real engineering, according to test indoor and test road outdoor, the material design and performance of three main base tapes:flexible base, semi-rigid base and rigid base were studied. Using the orthogonal sensitive analysis method and the BISAR procedure, the design parameter of roadbase courses were analyzed in detail; Combined with the construction of test road, the construction technology of three roadbase courses were compared; with the continuous examination on deflection and cracks, the cause was analyzed and effective treatments were proposed; using the life-cycle-cost-analytic method, the influence on the constructing cost of asphalt pavement about the design of roadbase was analyzed.The conclusions as follows:(1) With the large-scale Marshall method, Flexible base materials ATB-30 has the excellent anti-distortion capacity under high temperature, crack resistance performance under low temperature and fatigue-tolerance;using physical-mechanical method, ATB-25 has excellent low temperature crack resistance performance, the fatigue-tolerance and anti-distortion capacity under high temperature are also good; using physical-mechanical method, AC-30Ⅱalso has good fatigue-tolerance, anti-distortion capacity under high temperature and crack resistance performance under low temperature; AM-30 with traditional Marshall method has excellent crack resistance performance. Flexible base materials ATB-30 has the more superior anti-distortion capacity under high temperature, anti-crack capacity under low temperature and fatigue-tolerance.(2) Comparison the proportioning design, strength and rigidity of lean concrete and high fly ash content concrete:along with the addition of the flying ash and the reduction of cement, the compressive strength and rupture strength all reduce and the reduce trend became weaker. The fly ash plays micro-aggregate effect, pozzolanic effect and ball grinding effect. The proportion and age of fly ash, cement and aggregate affect the mechanical performance.(3) Compressive strength>flexural strength, compressive elastic modulus> flexural elastic modulus. With the increase of age, both the strength and modulus of cement-stabilized macadam are increasing. From linear equation:compressive strength Rc=0.0549T(age)+3.5782,R2= 0.999, the variation of compressive strength has little difference between pre-ratio and later.(4)Critical factors orthogonal sensitive analysis in pavement structure design show that the sensitivity sequence is thickness of base> subbase modulus> rigid base >base modulus, the calculation result of the bearing capacity of pavement show that the bearing capacity sequence is:rigid base>semi-rigid base> flexible base.(5) In the construction of flexible base, the thickness, temperature and prevent separation are key technologies, the construction thickness could be more than 5 times of grain diameter, control of compaction temperature should be determine by viscosity-temperature curve, and the roller compaction should complete before the temperature drops to 80℃.(6) The distribution density sequence of The cracks on asphalt pavement construction entity is:flexible base< semi-rigid base< rigid base, the width density sequence of crack is flexible base< semi-rigid base< rigid base, the maximum width sequence of crack is flexible base< semi-rigid base< rigid base. The result of the core-drilling at crack show that the main crack pattern is basement reflect crack. the too fast temperature drop speed and the low temperature is the main reason of the base course crack and the generation of reflect crack, which produce the crack on test road.(7) Evaluation different basement asphalt pavement with method of life cycle cost analysis. The results show that flexible base have a long service life than semi-rigid base; hold its service ability in a longer time; reduce the travel time, vehicles running costs and accident cost.(8) There are several essential points should be considered in basement pattern selection. The characteristics of rigid base, semi-rigid base and flexible base should be deeply analyzed combined with the local traffic volume, climate condition and hydrogeology condition. Consider the main performance requirements first and make a compromise on the subordinate performance requirements on the premise of guarantee the principle base performance requirements, and select the maximum economic efficiency base.更多还原