不同影响因素下大粒径多空隙沥青混合料疲劳性能试验研究

发布时间：2018-03-27 09:17

本文选题：大粒径多空隙沥青混合料　切入点：反射裂缝　出处：《广西大学》2014年硕士论文

【摘要】：反射裂缝作为旧水泥混凝土路面沥青加铺层和复合路面最常见的病害之一,一直以来都是道路工程界所面临的一大难题。大粒径多空隙沥青混合料具有粒径大、空隙多的特点,这种大粒径多空隙结构可有效地阻断裂缝尖端的扩展路径,消弱拉应力、拉应变的传递能力,可有效缓解旧水泥混凝土板接缝处沥青加铺层的应力集中现象,但目前对反射裂缝在大粒径多空隙沥青混合料中的扩展行为研究甚少。本文着重对大粒径多空隙沥青混合料的疲劳力学性能和沥青加铺层反射裂缝的扩展行为进行试验研究。采用直接拉伸、劈裂试验、三点弯曲及冲击韧性试验,确定在不同应力水平下粒径尺寸、空隙率及沥青种类、含量等参数变化对沥青混合料拉伸疲劳及抗弯拉性能的影响程度。试验结果表明,四种影响因素均对沥青混合料的疲劳性能有着较为显著的影响。研发了可模拟温度型反射裂缝疲劳试验的机械辅助装置,在室内理想条件下采用MTS及RMT试验机进行了不同加铺层结构疲劳破坏的对比试验,模拟沥青加铺层荷载型及温度型反射裂缝的扩展行为,分析了不同类型沥青加铺层反射裂缝的产生、发展过程。利用CT技术对大粒径多空隙沥青混合料和普通沥青混凝土的细观破裂过程进行扫描观测,获得沥青混合料试件在各种荷载作用下裂缝贯通的CT图像,分析沥青混合料图像的变化特征,研究受力模式和级配类型对沥青加铺层反射裂缝扩展特征的影响程度。结果表明,大粒径多空隙沥青混合料的裂缝主要沿大粒径骨料周围的沥青胶浆、界面层或空隙中扩展,有比较明显的分叉现象,整体呈“之”字形逐渐向上扩展,而普通沥青混凝土的裂缝基本沿垂直方向往上扩展,扩展路径为一条明显的主线,裂缝扩展速度快,缝宽较大。
[Abstract]:As one of the most common diseases in asphalt overlay and composite pavement of old cement concrete pavement, reflection crack has always been a difficult problem in road engineering. The large particle size multi-void structure can effectively block the crack tip propagation path, reduce the tensile stress and strain transfer ability, and effectively alleviate the stress concentration phenomenon in the asphalt overlay at the joint of the old cement concrete slab. However, there is little research on the propagation behavior of reflection cracks in large particle size and multi-voids asphalt mixture. This paper focuses on the fatigue mechanical properties of large particle size and multi-voids asphalt mixture and the propagation behavior of reflection cracks in asphalt overlay. By means of direct tensile test, splitting test, three-point bending test and impact toughness test, the particle size, porosity and asphalt type were determined under different stress levels. The experimental results show that the four factors all have a significant effect on the fatigue performance of asphalt mixture. A mechanical auxiliary device which can simulate the fatigue test of reflective cracks of temperature type was developed. The fatigue failure of different overlay structures was tested by using MTS and RMT test machines under ideal indoor conditions. The propagation behavior of reflective cracks of asphalt overlay under load and temperature is simulated and the generation and development process of reflection cracks in different types of asphalt overlay are analyzed. In this paper, the microfracture process of large size multi-void asphalt mixture and ordinary asphalt concrete was observed by CT scanning, and the CT images of crack penetration of asphalt mixture specimens under various loads were obtained. The change characteristics of asphalt mixture image are analyzed, and the influence of stress mode and gradation type on the reflection crack propagation of asphalt overlay is studied. The cracks of large particle size and multi-voids asphalt mixture mainly extend along the asphalt mortar around the large particle aggregate, and there is obvious bifurcation phenomenon in the interfacial layer or in the void, and the whole is gradually extending upward in the shape of "zigzag". On the other hand, the cracks of ordinary asphalt concrete basically extend upward along the vertical direction, and the propagation path is an obvious main line. The crack propagation speed is fast and the joint width is large.
【学位授予单位】：广西大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U414

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