Integrated approach for analyzing thermal effects on pavement construction-induced cracks

80年来，沥青路面的横向开裂问题一直是困扰公路工程技术人员的主要难题之一。已经进行了广泛的研究，产生了大量的文献和预测模型。传统上，横向裂纹是通过热裂纹模型来解释的，热裂纹模型可以是经验的，也可以是基于力学的。然而，这两种方法都不能充分解释这些裂缝的出现，因为它们的应用受到了严重的限制。在本建议中，将从以下几个方面考虑这个问题：(1)施工引起的裂缝，导致引发横向裂缝所必需的表面缺陷；(2)粘结强度对裂缝过程的重要性；(3)温度变化和缺陷沥青材料的反应所产生的应力。所提出的方法是在施工后对压实过程中产生表面裂缝的沥青结构进行建模。利用有限元方法模拟了空气和路面温度下降对裂缝结构应力应变状态的影响。将研究不同的情况，包括不同的特性、粘结值、温度变化率以及施工引起的裂缝的分布和特征。分析阶段的结果将被用来开发一种实验室技术，当路面受到温度变化的影响时，该技术可以准确地模拟现场条件。实验室模型将产生由温度变化引起的应力和应变，而不是当前模拟的条件，这些条件会在热处理的沥青材料上产生机械产生的应力。这一研究将对特别是热裂纹现象的根本治理产生重大影响。除了改善旅行时间、道路安全和恢复公众对路面行业的信心外，还将在初始投资和维护和修复成本方面实现巨大的经济节省。

For 80 years, the problem of transverse surface cracking of asphalt pavements has been recognized as one of the major dilemmas facing highway engineers. Extensive research has been performed that produced large volumes of literature, and predictive models. Transverse cracks are traditionally explained through thermal cracking models which may be either empirically or mechanistically based. However, both approaches fail to adequately explain the appearance of these cracks due to serious limitations in their applications. In this proposal the problem will be considered in terms of the following elements: (1) Construction induced cracks causing the surface defects necessary to initiate transverse cracking (2) The importance of bond strength on the process of cracking (3) Stress generated by changes in temperature and the response of the defected asphalt material. The proposed methodology is to model the asphalt structure after construction with surface cracks resulting from the compaction process. A Finite element method will be utilized to simulate the effects of dropping air and pavement temperatures on the stress-strain state of the cracked structure. Different scenarios will be examined including different properties, bond values, rate of change of temperature and distribution and characteristics of the construction induced cracks. The results of the analytical phase will be used to develop a laboratory technique that accurately simulates field conditions when the pavement is subjected to changing temperatures. The laboratory model will generate stresses and strains caused by the changing temperatures and not the currently simulated conditions which induce mechanically generated stresses on thermally treated asphalt materials. This research will have a significant impact on the fundamental basis treating the phenomenon of thermal cracking in particular. Great economic savings on the initial investments and maintenance and rehabilitation costs will be realized, in addition to improved travel time, road safety and restoring the public confidence in the pavement industry.