Abstract: In order to study the stiffness damage of the small beam in the strain fatigue test of asphalt mixture, the stiffness damage model of the small beam was established on the basis of the relative theory of materials mechanics. The damage laws of the stiffness of the small beam when the damage was developed from the lower part of the cross-section to the top and from the upper and the lower sides to the middle part were studied respectively. The results show that when the damage of small beam develops from bottom to top, the distance between neutral axis and top edge of the beam decreases firstly from the initial 0.5h, then increases gradually, and finally goes back to the initial position. Meanwhile, the stiffness attenuation of the small beam also passes through 3 stages: the stiffness decrease is significant firstly, and then becomes stable, and decreases sharply lastly. When the damage of the small beam extends from the upper and the lower sides to the middle, the position of the neutral axis remains unchanged, and the stiffness of the small beam decreases greatly at the initial stage, then decreases gradually, and finally tends to be stable.

Key words: highway engineering, asphalt mixture, strain fatigue, section stiffness, damage model

摘要： 为了研究沥青混合料应变疲劳试验中小梁的刚度损伤状况，基于材料力学的相关理论建立了小梁刚度损伤模型，分别研究了小梁的损伤由截面下部 往上和由上下两边往中间扩展时其刚度衰变规律。研究表明：当小梁的损伤由下往上扩展时，小梁的中性轴与截面上部的距离由初始的0.5h先减小，随后 又逐渐增大，最终又回到初始位置，同时，小梁的刚度衰减也经过3个阶段：小梁的刚度下降幅度较大阶段；小梁的刚度下降较为平缓阶段；小梁的刚度 下降的幅度又有所增大阶段。当小梁的损伤由上下两边向中间扩展时，中性轴位置保持不变，小梁的截面刚度在初始阶段下降幅度较大，随后逐渐下降， 最后趋于稳定。

关键词: 道路工程, 沥青混合料, 应变疲劳, 截面刚度, 损伤模型