基于弹性理论的沥青路面Top-Down开裂机理研究

Study on Top-down Cracking Mechanism in Asphalt Pavement Based on Theory of Elasticity

为了分析沥青混凝土路面Top-Down开裂机理,基于ABAQUS有限元分析方法,综合考虑老化和温度梯度造成的沥青路面内部模量梯度、突然降温、轮胎边缘的应力集中等因素,选取春季、夏季和冬季3个季节,及未老化缓慢降温、老化后忽然降温和老化后缓慢降温3种情况,建立了9个沥青混凝土路面结构有限元模型。对不同工况下沥青混凝土路面最大拉应力和剪应力的大小及位置进行了分析。结果表明:对于未老化缓慢降温和老化后缓慢降温的沥青混凝土路面,剪应力过大是沥青混凝土路面开裂的主要原因;对于老化后忽然降温的沥青混凝土路面,由于剪应力无明显变化,拉应力增加较多,拉应力过大是沥青混凝土路面开裂的主要原因。

In order to analyze the top-down cracking mechanism in asphalt concrete pavements, based on the method of finite element analysis with ABAQUS software, considering the modulus gradient in asphalt pavement, the sudden cooling down and the concentration of tire edge stress caused by aging and temperature gradient, selecting seasons of spring, summer and winter, considering the conditions of slowing cool down before aged, sudden cooling down after aged and slowing cool down after aged, we built 9 finite element models of asphalt concrete pavement. We analyzed the magnitudes and positions of the maximum tensile stress and the maximum shear stress of asphalt concrete pavement under different working conditions. The results indicate that （1） the excessive shear stress is the main reason for top-down cracks when the temperature of asphalt concrete pavement slowly cools down whether the pavement is aged or not; （2） when the temperature of asphalt concrete pavement suddenly cools down after aged, the tensile stress significantly increases due to the shear stress almost remains unchanged, so the excessive shear stress becomes the main reason for top- down cracks.