【作者】 关宏信；

【导师】 张起森； 郑健龙；

【作者基本信息】 中南大学 ， 道路与铁道工程， 2005， 博士

【摘要】 疲劳开裂是沥青路面结构的主要破坏形式之一,而损伤演化是伴随疲劳过程发生的。采用疲劳损伤理论来分析沥青路面的疲劳开裂问题是目前的研究热点之一,但由于沥青混合料具有明显的粘弹性性质,采用传统的疲劳损伤理论无法反映温度和频率对疲劳损伤演化的影响,分析沥青路面的疲劳损伤问题所得结论将具有一定的局限性。 本文首先分析了路面行车荷载周期作用下沥青路面的粘弹性应力响应规律,近似的定性分析和结构计算都表明,可以将沥青路面周期荷载作用下应力的周期变化简化成半正弦波形式,并具有与行车荷载变化相同的频率。这种简化处理为本文后续的沥青混合料粘弹性模型的建立和沥青路面粘弹性疲劳损伤分析奠定了基础。 在上述分析的基础上,从沥青混合料的粘弹性性质出发,利用能量耗散的观点,经理论推导得到了沥青混合料的粘弹性疲劳损伤模型,该模型能够综合反映温度、荷载大小和加载频率对疲劳损伤演化的影响。分析表明,可以利用该模型来分析沥青路面裂纹形成阶段的疲劳寿命问题。在模型建立的过程中,还提出了一种比较直观的新的疲劳损伤累积规律的判断方法,并从理论上探讨了“损伤等效状态”是否存在的问题,分析了室内试验证明不了“损伤等效状态”存在的原因。 针对本文建立的粘弹性疲劳损伤模型,进行了沥青混合料的室内试验,包括应力松弛试验和疲劳损伤试验,由前者得到沥青混合料的粘弹性材料参数,通过后者得到沥青混合了粘弹性疲劳损伤模型参数。分析了目前常用的沥青混合料室内疲劳试验方法在粘弹性疲劳损伤参数确定方面的适用性问题。 针对粘弹性疲劳损伤计算时间太长以致无法得到实际应用的问题,本文在分析目前疲劳损伤计算分析存在问题的基础上,提出了一种粘弹性疲劳损伤的简化计算方法,该方法可以大量减少计算时间,是原本无法完成的粘弹性疲劳损伤分析问题变为可能。 最后,本文利用所建立的粘弹性疲劳损伤模型和粘弹性疲劳损伤计算方法分析预测了沥青路面疲劳裂纹形成阶段的寿命,结果表明,本文所提出的模型和计算方法是可行的。更多还原

【Abstract】 Fatigue cracking is a main destroy form of asphalt pavements, and the damage always evolves with fatigue developing. Analyzing fatigue cracking problems of highway engineering with fatigue damage theory is becoming focus. However, it is not adapt to analyse fatigue damage evolvement of asphalt pavements with tradition fatigue damage models, because asphalt mixture is one of viscoelastic materials, as well the influence of temperature and time for damage evaluation can not be denoted by tradition fatigue damage models.Firstly, the stress response law of asphalt pavements under cycle vehicle loading is qualitatively analyzed and numeric calculated, which indicates that it is feasible on the assumption that the stress response law of asphalt pavements under cycle vehicle loading approximates to half sine wave and the frequency of stress cycle equales to the frequency of loading cycle. This approximate way is the fundation of viscoelastic fatigue damage model and viscoelastic fatigue damage life analysis in this study.Secondly, a viscoelastic fatigue damage model based on cycle stress law is deduced with energy dissipation concept, which starts from the viscoelastic constitutive relation. The influnce of temperature, loading frequency and stress to damage evolvement is denoted in this model. This model can be applied to analyse fatigue carcking initiation life of asphalt pavements. A new comprehensible method to judge fatigue damage cumulation law is deduced directly from damage evolvement law. The "damage equivalent state" is proved theoretically, and the reasons for "damage equivalent state" being not found by testing is discussed.Thirdly, the parameters of viscoelastic material and viscoelastic fatigue damage model is obtained by testing which includes stress relaxation tests and fatigue tests. It is discussed whether or not tradition fatigue testing methods can be applied to obtain parameters of viscoelastic fatigue damage model. A new method is put forwared to test viscoelastic fatigue damage parameters.Fourthly, for viscoelastic fatigue damage calculating, the calculating time is so long that viscoelastic fatigue damage calculating can not becompleted at present. The main problem of tradition fatigue damage calculating methods is discussed, and a new fatigue damage calculating method is put forward. Comparing with tradition fatigue damage calculating methods, the calculating time of the new method can be greatly reduced, which makes viscoelastic fatigue damage calculating be possible.Lastly, the fatigue life of asphalt pavements is forecasted by analyzing fatigue damage evolvement with the viscoelastic fatigue damage model and the viscoelastic fatigue damage calculating method developed in this study. The results indicate that the new model and the new calculating method developed in this study is feasible.更多还原