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针对柔性基层沥青路面主要病害形式Top-Down开裂开展病害机理研究,为病害预防提供技术支持,有助于提高道路服务水平,延长路面使用寿命。首先,对国内外目前柔性基层沥青路面Top-Down开裂研究成果进行了对比研究,分析了不同研究成果中对于Top-Down开裂形式、裂缝形成与发展机理提出的一致以及尚未达成共识的结论,确定以动态荷载下路面结构厚度、车辆荷载作为主要分析对象。然后,利用有限元计算软件进行实体建模,参考国内已建成道路选定代表路面结构,确定各项路面参数,基于子午线轮胎按照三向应力建模;分析动荷载作用下的应力最不利位置以及应力分布;选取车辆荷载作为主要变量,对动荷载作用下柔性基层沥青路面Top-Down裂缝起裂和发展的影响因素进行研究。基于断裂力学,以轴载和路面结构层厚度为主要变量,对微裂缝出现后影响裂缝发展的不同因素进行了对比。结果显示:当路面处于完整、连续的工作状态时,在动荷载作用下,剪应力τ是TopDown裂缝形成的主要原因;当路表出现微裂缝后,轴载对于裂缝发展的影响要远大于路面处于完整、连续状态时轴载的影响,应力强度因子K_Ⅰ和K_Ⅱ的峰值显著提高,建议在柔性基层路面设计、验算时加入剪应力验算指标。
Aiming at the disease mechanism of Top-Down cracking which is the main disease form of asphalt pavement on flexible base, it provides technical support for disease prevention and helps to improve the service level of road and prolong the service life of pavement. First of all, the current research on Top-Down cracking of flexible asphalt pavement at home and abroad are compared and the conclusions of the research results on Top-Down cracking, formation and development of cracks are consistent and have not reached consensus, Under the dynamic load, the pavement structure thickness and vehicle load are the main analysis objects. Then, the finite element calculation software was used to carry on the entity modeling. The pavement structure of the selected roads in China was established with reference to the pavement structure. The pavement parameters were determined and the radial tires were modeled according to the three-direction stress. The most unfavorable position under dynamic load and Stress distribution of the asphalt pavement, and select the vehicle load as the main variable to study the influencing factors of the initiation and development of the Top-Down crack of the flexible asphalt pavement under dynamic load. Based on the fracture mechanics, taking the axial load and pavement thickness as the main variables, the different factors affecting the crack development after the occurrence of micro-cracks are compared. The results show that the shear stress τ is the main cause of TopDown cracks under the dynamic load when the pavement is in a complete and continuous working condition. When microcracks in the road surface appear, the influence of the axial load on the development of fractures is far greater than that of the pavement In the intact, continuous state of the impact of the axle load, the stress intensity factor K_I and K_II peak increased significantly, it is proposed in the flexible design and calculation of the pavement, checking calculation added shear stress indicators.