【作者】 贾侃；

【导师】 沙爱民；

【作者基本信息】 长安大学 ， 道路与铁道工程， 2008， 博士

【摘要】 半刚性基层材料的疲劳性能是沥青路面结构性能的重要基础。不同材料组成、结构类型和环境条件下的半刚性基层材料的疲劳规律及参数不同。材料的疲劳变形规律表明,现行半刚性基层材料的弯拉模量设计值不能真实反映材料的实际力学性状,直接选用室内试件的模量测定值作为路面结构分析的材料参数,将导致计算结果出现较大偏差。因此,有必要系统研究半刚性基层疲劳特征规律和动态模量的衰变规律,明确反复荷载作用下半刚性基层的损伤形成及演化行为,为完善半刚性基层沥青路面设计指标提供重要依据。本文在总结国内外已有研究成果的基础上,比较分析了现有疲劳性能研究的室内试验方法,确定四点弯曲疲劳试验的标准试验方法。针对三种结构类型的水泥稳定碎石(悬浮密实结构、骨架密实结构和骨架空隙结构)、两种结构类型的二灰稳定碎石(悬浮密实结构和骨架密实结构)、均匀密实结构水泥稳定细料土以及水泥稳定砂砾开展了室内疲劳试验,并进而对半刚性基层材料疲劳性能的外部和内部影响因素进行评价。在此基础上,本文对半刚性基层材料的疲劳预估模型进行了理论和现场修正。依据室内疲劳试验和现场ALF试验,对半刚性基层的疲劳变形和模量衰变规律开展了系统研究,在深入分析半刚性基层材料疲劳性能的基础上研究确定了半刚性基层路面的疲劳设计参数。本文建立了四种不同半刚性基层材料的室内疲劳预估模型。提出了支承条件下和浸水条件下的室内疲劳试验方法,分析评价了支承条件和浸水条件对基层材料疲劳性能的影响。考虑外部和内部影响因素,对室内疲劳预估模型进行理论修正;同时,通过水泥稳定碎石基层的现场ALF试验,提出了水泥稳定碎石基层材料现场修正的疲劳损坏预估模型。半刚性基层材料梁试件底部拉应变在疲劳试验中的增加过程呈三阶段发展。应变增长第二阶段中应变与作用次数呈线性关系。通过梁底部拉应变发展第二阶段的应变曲线与回归直线的两个切点确定了应变稳定增加转折点与极限破坏转折点。半刚性基层材料的模量衰变曲线分为下降较快、降速稳定和急剧下降三个阶段,本文得出了半刚性基层材料在第二阶段的动态模量衰变率值。以半刚性基层材料室内弯拉模量衰变曲线的阶段过渡点和中点作为特征点,确定特征点处的模量衰变比值,并由初始动态弯拉模量值确定衰变后相应的动态弯拉模量值,并进行了ALF现场试验验证,进而提出了各种半刚性基层材料相应的弹性模量设计参考值。更多还原

【Abstract】 Based on the indoor test and existing results abroad and home, this paper develops a research on the fatigue property of four normal kinds of semi-rigid base materials. It presents test results of performance for three structural types of cement stabilized crushed rock including suspend-dense structure framework-dense structure and framework-pore structure, for two structural types of lime fly-ash stabilized crushed rock including suspend-dense structure and framework-dense structure, for cement stabilized soil and for cement stabilized gravel. By the probability analysis of Weibull on the results of fatigue test, the paper has a serial of fatigue prefigurative models. What’s more, amends these models linking to the factual pavement performance. The test method of the bending fatigue performance under supporting condition and under soaking condition was put forward. Then the test was done and the influences was analyzed.Based on having indoor fatigue test, dynamic modulus deterioration laws of four common semi-rigid base materials have been studied. The paper has analyzed tension strain at the bottom of samples and presented the calculation method as well as value of the limit tension strain. Deterioration laws of each material modulus under fatigue loading have been analyzed. Modulus deterioration has three stages. Deterioration rate differs from stress level. The higher the stress level is, the greater the deterioration rate is. At last, the relationship between deterioration laws of dynamic modulus and structural type of semi-rigid base course materials was investigated. The paper summarized the selection method of modulus of semi-rigid base course materials in every country. Based on having indoor fatigue test, dynamic modulus deterioration laws of semi-rigid base materials have been studied. Modulus deterioration has three stages. The stage transition point and neutral point of modulus deterioration curve is proposed as the specific points. The deteriorated dynamic modulus is determined by the initial dynamic modulus. At last, the corresponding design effective modulus of the various working status of semi-rigid base course materials has been determined.更多还原