纤维沥青混合料冻融劈裂试验及其数值模拟

发布时间：2018-05-25 23:30

本文选题：沥青混凝土 + 纤维种类　；参考：《安徽理工大学》2017年硕士论文

【摘要】：纤维沥青混合料成分组合复杂,其复杂性则导致了纤维沥青混合料的力学特性也随之相应复杂。本文研究以纤维种类、掺量以及冻融次数为参数,从纤维沥青混凝土的劈裂试验出发,评价纤维沥青混凝土的冻融劈裂性能。通过大量的室内试验与理论分析,具体研究了掺加聚酯纤维、玄武岩纤维、木质素纤维及各种纤维掺量为0.3%、0.35%、0.4%、0.45%情况下的沥青混合料在清水作用下的水稳定性情况,为以后纤维种类及掺量对沥青混合料的影响做出参考。本文还建立了三维沥青混合料的有限元劈裂模型,通过对比数值模拟结果与实测的结果两者之间的关系,由此验证得出建立纤维沥青混合料马歇尔试件有限元模型的合理性;针对纤维沥青混合料马歇尔试件劈裂模型数值模拟所得的应力应变云图的分布情况,具体分析沥青混合料试件的受力特性。试验结果与数值模拟结果表明:(1)随着冻融次数的增加,掺加纤维的沥青混凝土试件的冻融劈裂强度降低;其主要原因是试件中的水在冻融循环过程中经历不断的结冰和融化,这就直接导致试件内部结构的逐渐破坏。(2)随着纤维掺量的增加,未冻融试件劈裂强度变化的基本趋势相同,几乎都是先上升后下降。冻融次数为2、4、6的情况下试件的劈裂强度与未冻融的规律相似。主要是因为纤维掺量过高时会产生结团现象,导致纤维与沥青及集料拌和不均匀,劈裂强度也就随之而降低。冻融次数相同时,不管是2、4或者6次,冻融劈裂强度最小的都是纤维掺量最小的试件。在相同的纤维掺量条件下,无论是0.3%、0.35%、0.4%还是0.45%,劈裂强度最小的都是冻融次数最多的试件。(3)纤维掺量为0.3%、0.35%、0.4%、0.45%在经过6次冻融循环后,沥青混凝土试件的劈裂强度都会有最佳值;在本文的试验研究范围内纤维的最佳掺量为0.4%,最佳纤维为玄武岩纤维。以上两个数据条件下,纤维的增强作用为最佳,此时试件的冻融劈裂性能最好。(4)通过对超声波试验数据中波速和纤维沥青混合料马歇尔试件强度检测的处理结果可知,采用指数函数拟合超声波传播速度和沥青混合料冻融循环后的劈裂强度,正确地反映沥青混合料在冻融过程中的性能衰减。对于掺加聚酯纤维的试件,波速与强度的拟合公式为f = 4.42477×10-7e0.0031v,R~2 = 0.89431;对于掺加玄武岩纤维的试件,波速与强度的拟合公式为f = 1.25069×10-8e0.00467v,R^=0.86403;对于掺加木质素纤维的试件,波速与强度的拟合公式为f=5.05944×10-11e0.00487v,R~2= 0.96903。采用超声波法进行沥青混合料冻融破坏试验的研究,利用波速的变化来反映冻融破坏程度,冻融循环后试件的破坏程度与冻融循环次数有关。(5)建立了三维的掺入纤维的马歇尔试件的ANSYS分析结构模型,通过面面接触的加载方式模拟沥青混合料的劈裂试验;基于冻融劈裂试验结果和超声波检测所得到的试验数据,建立三维的纤维沥青混凝土有限元模型;通过对数值模拟和实测结果之间的对比分析,验证建立纤维沥青混凝土马歇尔试件有限元模型的合理性,得出相应的规律。
[Abstract]:The composition of fiber bitumen mixture is complex and its complexity leads to the complexity of the mechanical properties of fiber asphalt mixture. In this paper, based on the splitting test of fiber asphalt concrete, the freeze-thaw splitting properties of fiber asphalt concrete are evaluated with the parameters of fiber type, mixing amount and freezing thawing times. In the internal test and theoretical analysis, the water stability of asphalt mixture mixed with polyester fiber, basalt fiber, lignin fiber and all kinds of fibers under the action of 0.3%, 0.35%, 0.4%, 0.45% is studied in detail, which can be used as a reference for the effect of fiber type and content on the asphalt mixture. By comparing the relationship between the numerical simulation results and the measured results, the reasonableness of establishing the finite element model of the Marshall specimen for the fiber asphalt mixture is verified by comparing the relationship between the numerical simulation results and the measured results, and the distribution of the stress and strain cloud images obtained by the numerical simulation of the splitting model of the fiber asphalt mixture Marshall specimen The results and numerical simulation results show that: (1) the freezing thawing splitting strength of the reinforced asphalt concrete specimen is reduced with the increase of the number of freeze-thaw. The main reason is that the water in the specimen is frozen and thawing continuously during the freezing and thawing cycle, which is directly caused by the freezing thawing cycle. The internal structure of the specimen is gradually destroyed. (2) with the increase of fiber content, the basic trend of splitting strength of unthawing specimens is the same, almost all of them rise first and then decrease. The splitting strength of the specimen under the condition of freezing thawing is 2,4,6 is similar to that of unfrozen thawing. With the uneven mixing of the asphalt and the aggregate, the splitting strength decreases. When the freezing and thawing times are the same, whether the freezing thawing splitting strength is the least, the minimum ratio of the freeze-thaw splitting is the least amount of fiber. Under the same fiber content, whether it is 0.3%, 0.35%, 0.4% or 0.45%, the minimum splitting strength is the test with the most freezing thawing times. (3) (3) fiber content of 0.3%, 0.35%, 0.4%, 0.45% after 6 freeze-thaw cycles, the splitting strength of asphalt concrete specimens will have the best value; in this paper, the optimum fiber content is 0.4%, the best fiber is basalt fiber. Under the two data conditions, the fiber reinforcement is the best, at this time the specimen freezing. The performance of thawing splitting is the best. (4) through the processing results of the wave velocity and the strength test of the Marshall specimen of the fiber asphalt mixture, it is found that the exponential function fitting the velocity of ultrasonic wave and the splitting strength of the asphalt mixture after the freezing and thawing cycle can correctly reflect the performance attenuation of the asphalt mixture during the freezing and thawing process. The fitting formula of wave velocity and strength is f = 4.42477 x 10-7e0.0031v, R~2 = 0.89431, and the fitting formula of wave velocity and strength is f = 1.25069 * 10-8e0.00467v, R^=0.86403 for specimens with basalt fiber, and the fitting formula of wave velocity and strength is f=5.05944 x 10-11e for the specimens added with lignin fiber. 0.00487v, R~2= 0.96903. is used to study the freezing thawing failure test of asphalt mixture by ultrasonic method, using the change of wave velocity to reflect the degree of freezing and thawing damage. The damage degree of the specimen after freezing and thawing cycle is related to the number of freezing and thawing cycles. (5) a three-dimensional structure model of Marshall specimen with a fiber is established, and the surface contact is made through the surface contact. The splitting test of asphalt mixture is simulated by loading method. Based on the test data of freezing thawing splitting test and ultrasonic testing, a three-dimensional finite element model of fiber asphalt concrete is set up. The finite element model of the Marshall specimen of fiber asphalt concrete is verified by comparison and analysis between the numerical simulation and the measured results. The rationality and the corresponding law.
【学位授予单位】：安徽理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U414

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