预切口纤维沥青混合料低温开裂性能研究

发布时间：2018-05-05 14:54

  本文选题：反射裂缝 + 三点弯曲加载试验　； 参考：《安徽理工大学》2017年硕士论文

【摘要】：反射裂缝是沥青路面冬季破坏的主要诱因之一。在低温收缩和荷载的共同作用下,下卧层出现开裂,裂缝处的应力集中致使裂缝向上开展,裂缝处的应力集中比没有裂缝的部位大,易超过沥青混合料面层的极限抗拉强度,引起面层的开裂。开展沥青路面低温反射裂缝低温抗裂性能以及裂缝开展行为研究,可以为路面面层混合料设计提供理论依据;研究反射裂缝的扩展行为对预防沥青混合料面层的早期破坏具有重大意义。总结了影响路面面层的反射裂缝开展的各个因素,发现在沥青混合料中掺入纤维有助于改进沥青路面的抗裂性能,因此研究掺入不同纤维的沥青混合料的低温抗裂性能,并用预切口模拟沥青路面面层底部预先存在的裂缝,研究存在于不同位置的反射裂缝在受荷载作用下的扩展行为。设计了预切口小梁三点弯曲加载试验,将温度作为小梁试件低温开裂性能的影响因素,将试验温度定为-10℃、0℃、10℃;为研究纤维对于沥青混合料小梁试件的开裂性能的改进作用,将掺入聚酯纤维、玄武岩纤维和木质素纤维的沥青混合料与不掺入纤维的混合料进行对比试验;试验对路面反射裂缝进行模拟,在试件底部预制切口深度为10mm的预切口,将预切口与中心的距离定为:Omm、20mm、40mm,对具有不同切口的试件进行三点弯曲加载试验。结果表明,预切口小梁三点弯曲加载试验很好地模拟了沥青混合料路面的低温开裂特性和混合料试件的反射裂纹开展行为;试验温度愈低,试件抗裂性能愈好;玄武岩纤维具有稳定地改善沥青混合料抗裂性能的作用;切口与荷载的水平偏移距离愈大,即反射裂缝偏移中心荷载的水平距离愈大,则试件抗裂性能愈强。采用ANSYS有限元软件模拟了小梁在-10℃试验时裂缝的开展行为。通过试验结果分析、断裂力学分析和有限元分析,得到了裂缝开展的起裂角的计算值、试验值和模拟值,用于描述裂缝开展行为。分析结果表明,小梁试件底部的反射裂缝开展行为具有一定的规律,针对不同位置的裂缝,给出了不同的起裂角范围,衡量裂缝开展行为。当裂缝偏移中心加载位置距离x=0mm时,起裂角θ0范围在0°至3.5°之间。当x=20mm时,起裂角范围在6.9至17.5°之间较为合理。当x=40mm时,起裂角的开展范围大概在20°至30°之间较为合理。
[Abstract]:Reflection crack is one of the main causes of asphalt pavement damage in winter. Under the joint action of low temperature shrinkage and load, the stress concentration in the lower horizontal layer cracks, the stress concentration in the cracks causes the cracks to develop upward, the stress concentration in the cracks is larger than that in the parts without cracks, and it is easy to exceed the ultimate tensile strength of the asphalt mixture surface. Cause the surface to crack. The research on low temperature crack resistance and crack development behavior of asphalt pavement can provide theoretical basis for pavement pavement mixture design. It is of great significance to study the propagation behavior of reflection crack to prevent the early failure of asphalt mixture surface. This paper summarizes the factors that affect the development of reflective cracks in pavement surface, and finds that adding fiber to asphalt mixture is helpful to improve the crack resistance of asphalt pavement, so the low temperature crack resistance of asphalt mixture with different fibers is studied. Pre-cut is used to simulate the pre-existing cracks at the bottom of the asphalt pavement surface, and the propagation behavior of the reflection cracks in different locations under the action of load is studied. The three-point bending test of pre-cut trabeculae was designed. The temperature was taken as the influence factor of the low-temperature cracking property of the trabecular specimens, and the test temperature was -10 鈩，

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