纤维沥青应力吸收层中纤维与沥青的作用机理研究

发布时间：2018-03-14 18:19

本文选题：应力吸收层　切入点：纤维　出处：《重庆交通大学》2014年硕士论文　论文类型：学位论文

【摘要】：刚柔复合路面是一种长寿命路面结构形式，，这种路面结构减少了沥青的使用量，同时弥补了刚性路面行车舒适度的不足。它刚柔相济，改善了道路的使用性能。但这种路面结构中的刚性基层存在施工接缝和原生裂纹缺陷，在复杂的交通组成和恶劣环境因素的联合作用下，复合路面会出现很多早期病害，反射裂缝就是其中一种常见病害。纤维沥青应力吸收层技术可以有效降低、延缓刚柔复合型路面的反射裂缝，然而然而我国引入这种技术时间较短，相关性能及机理研究较少。研究中先以表面能理论为基础，对纤维、沥青以及水泥砼切片进行接触角测量实验，通过计算粘附功对材料进行优选及评价；然后建立了单根纤维有限元接触模型，模拟单根纤维在基体中的情况，分析纤维-沥青界面的受力特点；最后，建立纤维织物有限元模型，分析纤维织物整体力学性能。研究得到主要的结论如下所示： ①4号纤维与沥青的粘附功最大，往下依次是2号纤维、1号纤维、3号纤维；橡胶沥青与纤维的粘附功最大，往下依次是SBS改性沥青、乳化沥青。所以，在纤维封层这种复合材料中使用4号纤维和橡胶沥青更加有利于增强其结构稳定性、提高其抗裂效果。 ②橡胶沥青与水泥砼切片的粘附功最大，往下依次是SBS改性沥青、乳化沥青。所以选用橡胶沥青最为纤维封层的胶结材料可以加强纤维封层与水泥砼面板的粘结力。 ③对单根纤维模型进行受力模拟发现，ANSYS计算的纤维-沥青界面的剪应力变化趋势与弹塑性基体模型的相似。 ④当纤维封层受拉达到极限破坏状态时，如果纤维过短，纤维将很容易从基体中拔出，纤维的高强性能将得不到充分发挥，所以为使纤维的强度得到充分利用，其长度宜超过一临界值；但纤维过长，其分担扩散基体应力的作用增长不明显，会造成浪费。所以在纤维沥青碎石封层的设计时，应选择合理的纤维长度。 ⑤纤维的增强作用与纤维/沥青界面的粘结性能密切相关：界面粘结太弱，将无法充分发挥纤维的增强作用，从而导致材料和经济的浪费；粘结良好的界面不仅可以很好的传递应力，同时也可以延缓界面的脱粘。所以为了增强材料界面的粘附性能，我们可以合理地选择纤维封层的组成材料，这也可以有效提高纤维封层的力学性能。 ⑥纤维的加入能够限制、约束沥青基体的应变；纤维端部应力集中造成的纤维端部过大的应变可能使纤维端部与沥青基体脱粘，所以纤维端部对纤维封层增强作用的贡献非常小。 ⑦纤维织物模型中加入短纤维（长度是长纤维的1/6）能够降低长纤维界面剪应力的合力，可以进一步吸收、分散基体应力，增强了模型的整体力学性能。 ⑧纤维封层中的纤维是二维乱向分布的，应力作用方向上的纤维利用率有限，纤维的分布与取向对荷载作用下纤维的利用率有很大的影响，纤维的取向越接近荷载作用方向，纤维的利用效率愈高。
[Abstract]:Rigid flexible composite pavement is a long-life pavement structure, the pavement structure to reduce the amount of asphalt, and compensate for the lack of rigid pavement driving comfort. It improves the performance of the road move among force and soft, rigid base. But this pavement structure exists in the application of Engineering defect seams and original cracks, the combined effect of traffic the composition and the harsh environment of complex factors, there will be a lot of composite pavement early disease, is one of the most common diseases of reflection crack. The fiber asphalt stress absorbing layer technology can effectively reduce the reflection crack, rigid flexible composite pavement type delay, however our country introduces this technology in a relatively short time, less research related to performance and the mechanism.
In the first study on the basis of surface energy theory, the fiber asphalt and cement concrete sections for contact angle measurement experiment, by calculating the adhesion work selection and evaluation of materials; and then set up a single fiber contact finite element model to simulate the single fiber in the matrix analysis, the interface of Fiber Asphalt Stress Characteristics; finally, a finite element model of fiber fabric, analysis of fabric mechanical properties. The main conclusions are as follows:
The work of adhesion No. 4 fiber and asphalt is the largest, followed by a 2 fiber, No. 1, No. 3 fiber, fiber; adhesion work of asphalt rubber and fiber is the largest, followed by SBS modified asphalt, emulsified asphalt. Therefore, more conducive to enhance the stability of the structure using 4 fiber and rubber asphalt in fiber the seal in the composite, improve its crack resistance.
2. The adhesion work of rubber asphalt and cement concrete slice is the largest, followed by SBS modified asphalt and emulsified asphalt. Therefore, the bonding material of rubber asphalt and the most fiber sealing layer can enhance the bonding force between fiber seal and cement concrete panel.
3. The stress simulation of a single fiber model shows that the shear stress of the fiber asphalt interface calculated by ANSYS is similar to that of the elastoplastic matrix model.
When the fiber seal tension reaches the ultimate state, if the fiber is too short, the fiber will be easily pulled out from the matrix, high performance fibers can not be brought into full play, so as to make full use of the strength of the fiber, its length should exceed a critical value; but the fiber is too long, its share of diffusion the matrix stress growth is not obvious, will cause waste. So in the design of fiber asphalt pavement surface, fiber length should be selected.
The enhancement effect of fiber and fiber / bonding properties of asphalt interface is closely related to the interface bond is too weak, will not be able to give full play to the enhancement of the fiber, which leads to the waste of material and economy; good bonding interface not only can well transfer the stress, but also can delay the debonding interface. So in order to enhance the adhesion the performance of the material interface, we can reasonably choose the material composition of fiber seal, which can effectively improve the mechanical properties of fiber seal.
The fiber is added to limit strain constraint matrix asphalt strain; fiber end fiber end stress concentration caused by too large may make the fiber end with asphalt matrix debonding, so the fiber ends of the fiber seal enhancement contribution is very small.
Join the short fiber fabric model (long fiber length is 1/6) can reduce the force of long fiber interfacial shear stress, can further absorption, dispersion matrix stress, enhance the overall mechanical properties of the model.
The fiber seal fiber in two-dimensional random distribution, stress direction of the fiber utilization rate is limited, distribution and orientation of the utilization of fiber on fiber loading rate has a great influence on the orientation of the fiber is close to the loading direction, the fiber utilization efficiency is high.

【学位授予单位】：重庆交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U414

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