沥青混合料单轴贯入试验的细观分析

发布时间：2018-07-03 18:40

本文选题：沥青混合料 + 单轴贯入试验　；参考：《湖南大学》2014年硕士论文

【摘要】：非均布荷载给路面结构带来较大的剪切应力，然而现有路面设计方法中却较少考虑沥青混合料的抗剪切性能，这也是沥青路面产生较大范围损伤的基本原因，因此沥青混合料的抗剪性能在设计中应着重考虑。然而,由于试验方法的复杂性及试验结果的变异性较大，通过试验获得沥青混合料的抗剪性能方法未能大范围地应用于工程领域。以离散单元法为基础的细观结构模拟方法，不仅避免了大量的试验，而且能够从细观尺度深入分析沥青混合料的基本性能，并且这个模型可用于探究沥青混合料这种复杂不连续介质的力学行为。为了从细观结构的角度分析沥青混合料的剪切特性，本研究使用离散单元法建立评价沥青混合料抗剪强度和细观结构的模拟试验方法。主要的研究内容包括以下几个方面：（1）基于离散元理论建立了沥青混合料单轴贯入试验的数值模型，并对模型在荷载作用下的力学响应进行了计算分析，得到了单轴贯入压头压应力、模型内最大剪应力随试件应变的发展规律以及模型内位移矢量和接触力矢量分布情况。（2）分析加载速度对试验结果的影响，试件强度随着加载速度的增加而增加。尝试建立了试件尺寸和压头直径与公称最大粒径的关系，试件尺寸和压头直径对试验结果影响显著，对于AC-25和AC-20级配混合料，推荐使用试件尺寸H×D=100mm×100mm，压头直径为28.5mm；对于AC-13级配混合料，可同时使用标准马歇尔试件进行试验。研究了宏观因素中的级配与公称最大粒径和空隙率与微观因素中的颗粒刚度、平行粘结强度和平行粘结半径对混合料抗剪强度的影响，总结出强度随着孔隙率的降低增加，，随着颗粒刚度、平行粘结强度和平行粘结半径的增加而增加。（3）通过数值模拟结果，提出了基于离散单元法评估沥青混合料抗剪强度的方法，对比单轴贯入试验结果与无侧限抗压强度试验结果，确定混合料的抗剪参数C和φ的公式。
[Abstract]:Non-uniform load brings large shear stress to pavement structure. However, the shear resistance of asphalt mixture is less considered in existing pavement design methods, which is also the basic reason of asphalt pavement damage. Therefore, the shear resistance of asphalt mixture should be considered in the design. However, due to the complexity of the test method and the variability of the test results, the shear performance of asphalt mixture can not be widely used in the engineering field. The mesoscopic structure simulation method based on discrete element method not only avoids a large number of tests, but also can analyze the basic performance of asphalt mixture from the meso scale. And this model can be used to study the mechanical behavior of asphalt mixture, a complex discontinuous medium. In order to analyze the shear characteristics of asphalt mixture from the point of view of meso-structure, a simulation test method for evaluating the shear strength and meso-structure of asphalt mixture was established by using discrete element method. The main research contents are as follows: (1) based on discrete element theory, the numerical model of asphalt mixture uniaxial penetration test is established, and the mechanical response of the model under load is calculated and analyzed. The compressive stress of uniaxial pressure head, the development rule of maximum shear stress with specimen strain and the distribution of displacement vector and contact force vector in the model are obtained. (2) the influence of loading speed on the test results is analyzed. The strength of the specimen increases with the increase of loading speed. The relationship between the size of the specimen and the diameter of the pressure head and the nominal maximum particle size is established. The size of the specimen and the diameter of the head have a significant effect on the test results. For the AC-25 and AC-20 graded mixtures, it is recommended to use the specimen size H 脳 D 100 mm 脳 100 mm and the pressure head diameter 28.5 mm. For the AC-13 grade mixture, the standard Marshall specimen can be used for the test at the same time. The effects of gradation and nominal maximum particle size and void ratio in macro factors and particle stiffness, parallel bond strength and parallel bonding radius on shear strength of mixture are studied, and it is concluded that the strength increases with the decrease of porosity. With the increase of particle stiffness, parallel bond strength and parallel bonding radius, a new method based on discrete element method is proposed to evaluate the shear strength of asphalt mixture. The formulas of shear parameters C and 蠁 are determined by comparing the results of uniaxial penetration test and unconfined compressive strength test.
【学位授予单位】：湖南大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U414

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