基于有限元法的级配碎石基层沥青路面疲劳寿命预估

发布时间：2018-06-22 04:20

  本文选题：级配碎石 + 有限元法　； 参考：《重庆交通大学》2015年硕士论文

【摘要】：与传统半刚性基层沥青路面相比,级配碎石基层沥青路面具有排水性好、行车舒适度提高的特点,可减小基层与面层的模量差,降低反射裂缝的出现几率。然而,级配碎石属于无粘结性材料,其力学强度主要依靠骨料之间的嵌挤,需要形成骨架密实型结构,并且在有侧限条件下才能发挥较好的受力作用。本文通过试验及理论模拟研究,优选级配碎石基层的级配类型和层间粘结类型,力求弥补级配碎石力学强度的不足,充分发挥其排水性能良好等优点,使之在公路建设中得到更广泛的应用。通过静态CBR试验和回弹模量试验,发现级配碎石具有最大干密度越大,对应的CBR值越大,变形率相应越小,回弹模量越大的特点。在此基础上,运用Cooper气动伺服试验机进行动态CBR试验,测试应变变化的相关系数以及蠕变模量值,变化率越小,蠕变模量值增加,力学性能越优。运用ABAQUS有限元软件构建模型,从上到下依次分为沥青混合料面层、稀浆封层、透层油(乳化沥青)、级配碎石、土基。为体现级配碎石的颗粒性及非均匀性特点,采用D-P模型对其进行定义;定义面层和稀浆封层为弹性材料。优选三种基层级配,分别设置不同封层厚度条件,施加标准荷载和边界条件,计算有限元模型,对竖向位移、轴向应力和剪切应力进行对比分析。经过试验研究和理论分析,改善级配碎石基层的力学性能有助于提高柔性基层沥青混合料路面的强度和抗变形能力;使用粗颗粒较多的稀浆封层级配类型ES-3,并适当增加封层厚度,有益于路面结构层间粘结强度提高;级配类型、封层厚度两个因素,级配类型影响较明显。温度是柔性基层沥青路面不可忽视的影响因素,经过竖向位移和Mises应力综合分析,得出在荷载作用下,温度在0~10℃范围内对路面结构的影响最小。本文采用自制模具成型疲劳试验试件,以45°斜剪试验作为疲劳试验方法,结果表明疲劳行为与级配碎石基层类型及层间粘结情况有关,依据试验测出的疲劳作用次数,结合基层级配碎石回弹模量、封层厚度、沿着行车方向层间应力进行疲劳寿命预估方程的拟合,得出建议性的疲劳寿命预估模型;同时,拟合结果具有保守性和延展性,具有一定的实际应用价值。
[Abstract]:Compared with the traditional semi-rigid base asphalt pavement, graded crushed stone base asphalt pavement has the characteristics of better drainage and better driving comfort, which can reduce the modulus difference between the base and surface layer and reduce the probability of reflection cracks. However, graded macadam is an unbonded material, its mechanical strength mainly depends on the intercalation between aggregates, and it needs to form a dense skeleton structure, and it can play a better force under the condition of side limit. In this paper, through experimental and theoretical simulation, the gradation type and interlaminar bond type of graded crushed stone base are selected to make up for the shortage of mechanical strength of graded crushed stone and to give full play to its good drainage performance. So that it is more widely used in highway construction. Through static CBR test and elastic modulus test, it is found that the higher the maximum dry density, the larger the CBR value, the smaller the deformation rate and the greater the resilience modulus of graded crushed stone. On this basis, the dynamic CBR test is carried out with Cooper pneumatic servo testing machine. The correlation coefficient of strain variation and creep modulus are measured. The smaller the change rate is, the higher the creep modulus value is, and the better the mechanical properties are. Abaqus finite element software is used to construct the model, which is divided into asphalt mixture surface layer, slurry seal layer, permeable oil (emulsified asphalt), graded crushed stone and soil foundation. In order to reflect the particularity and non-uniformity of graded macadam, D-P model was used to define it, and the surface layer and slurry seal layer were defined as elastic materials. Three kinds of base-bed gradation were selected, different sealing layer thickness conditions were set up, standard load and boundary conditions were applied, finite element model was calculated, and vertical displacement, axial stress and shear stress were compared and analyzed. Through experimental research and theoretical analysis, improving the mechanical properties of graded crushed stone base is helpful to improve the strength and deformation resistance of asphalt mixture pavement with flexible base. It is beneficial to increase the interlayer bond strength of pavement structure by using the slurry sealing hierarchy type ES-3 with more coarse particles and increase the thickness of sealing layer properly. The gradation type and sealing layer thickness are two factors which have obvious influence on the interlayer bond strength of pavement structure. Temperature is an important influence factor of asphalt pavement with flexible base. Through the comprehensive analysis of vertical displacement and Mises stress, it is concluded that the influence of temperature on pavement structure is the least in the range of 0 ~ 10 鈩，

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