特粗粒径沥青碎石裂缝缓解层防裂机理分析

反射裂缝是旧水泥混凝土路面上沥青混凝土加铺层的主要病害之一，目前尚无理想的解决方法，针对这一问题，提出了采用特粗粒径沥青碎石AM-40作为裂缝缓解层的方法，利用特粗粒径沥青碎石的多空隙结构阻断裂缝尖端的扩展路径，消散及吸收由交通荷载及环境温度变化所产生的应力及应变，减小接缝处加铺层的应力集中现象。采用三维有限元法对设置普通沥青混凝土与特粗粒径沥青碎石2种类型裂缝缓解层的加铺结构进行力学对比分析可知，后者的荷载应力、温度应力及耦合应力均小于前者的应力值。通过加铺层试验路观测与理论计算分析表明，特粗粒径沥青碎石裂缝缓解层可有效地防止或减缓水泥混凝土路面上沥青混凝土加铺层的反射裂缝。

Anti-Cracking Mechanism Analysis of Cracking Relief Layer of Extra Coarse Asphalt Macadam

The reflective cracking is one of the main damages of asphalt overlay on the old concrete pavements, there is no ideal method to solve it still now, aiming at this problem, a method of using the extra Coarse asphalt macadam as cracking relief layer is proposed, a great deal of void in the extra coarse asphalt macadam can obstruct the extending path of crack tip, dissipate or absorb streses and strain of vehicle load and environmental temperature variety, reduce the stress centralization of asphalt overlay at joints of cement concrete pavement. The 3-D finite element method is used to analyze the cracking relief layer of asphalt concrete and extra coarse asphalt macadam, load stress, thermal stress and coupling stress of the latter are less than the former. The investigations of testing highway and results of theoretic calculation indicate that the extra coarse asphalt macadam layer can prevents asphalt concrete overlay from cracking effectively.