钢桥面沥青混凝土铺装疲劳裂缝扩展数值分析

为揭示钢桥面沥青混凝土铺装裂缝行为机理,分析了铺装层疲劳裂缝扩展阻力曲线,利用复合梁疲劳试验数据,采用三维有限元方法,研究了铺装层裂缝启裂、扩展直至失稳的全过程。结果表明:疲劳裂缝扩展阻力曲线形式与材料类型和"铺装层 钢板"复合结构有关系;当天然初始裂缝长度为0时,疲劳裂缝扩展一般存在3个阶段:起始扩展区、稳态扩展区和失稳扩展区,此时复合梁的疲劳寿命接近800万次;当初始裂缝长度为10 mm时,疲劳裂缝扩展直接进入失稳扩展区,疲劳寿命约为200万次;裂缝增长率与荷载作用次数之间存在良好的非线性关系。可见,钢桥面铺装层宜选用空隙率小、易密实的铺装材料,同时可根据荷载作用次数推断出铺装层疲劳裂缝的状态。

Numerical analysis of fatigue crack propagation in asphalt pavement on steel deck

In order to discover the crack mechanism of asphalt pavement on steel deck,the resistance curve of fatigue crack propagation was simulated,the whole process of crack beginning,propagation and instability was analyzed based on 3D finite element method and experiment data.Analysis result shows that the form of resistance curve depends on the type of material and the composite beam of pavement and steel plate.When the natural crack length is 0,the propagation of fatigue crack has 3 phases such as initial propagation zone,stable propagation zone and unstable propagation zone,and the total fatigue life almost reaches 8 million times;when the natural crack length is 10 mm,the propagation of fatigue crack in asphalt pavement may start from unstable propagation zone,the total fatigue life may be 2 million times;there is a good nonlinear relationship between crack increment ratio and loading times.So for steel deck pavement,the materials with little porosity and good dense degree should be selected,and fatigue crack propagation phase can be judged by loading times.