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基于SCB试验的沥青混合料复合型断裂数值模拟

Numerical simulation of mixed fracture in asphalt mixture based on SCB test

  • 摘要: 沥青混合料的断裂性能是影响沥青路面断裂的主要因素之一。沥青路面断裂状况通常是多种断裂模式共同作用导致的,难以通过单一断裂模式(Ⅰ型或Ⅱ型)准确表征。针对沥青混合料的复杂断裂特性,基于半圆弯曲(SCB)试验构建扩展有限元模型。通过调整支撑间距与初始裂纹位置,系统研究沥青混合料Ⅰ型、Ⅱ型及Ⅰ-Ⅱ复合型断裂模式下材料的裂纹扩展规律与应力分布。研究结果表明,模型可有效预测裂纹扩展路径,数值模拟结果与实验观测高度吻合;试件始均初始裂纹尖端起裂,并沿着一定路径向加载点延伸直至断裂;且支撑位置会影响裂纹的扩展路径。复合型断裂的裂纹尖端应力约为单一型断裂的2.8倍。此外,进一步研究初始裂纹长度对沥青混合料断裂的影响,发现裂纹长度仅影响模型起裂位置,而不会改变裂纹扩展的最终路径。

     

    Abstract: The fracture properties of asphalt mixture are one of the primary factors influencing cracking in asphalt pavements. The cracking condition of asphalt pavements is typically the result of a combination of multiple fracture modes, making it difficult to accurately describe with a single mode I or mode II fracture mode alone. To address the complex cracking patterns of asphalt mixtures, an extended finite element model was established based on the semi-circular bend (SCB) test. By varying the support and initial crack positions, the crack propagation trends and stress distributions under mode I, mode II, and mode I-II mixed-mode fractures in asphalt mixtures were investigated. The results indicated that the crack propagation paths predicted by the model aligned well with the experimental observations. Specimens always initiated cracking at the tip of the preset crack and extended along a certain path towards the loading point until failure occurred. The location of the braces affected the path of crack propagation. The crack tip stress of the mixed fracture was approximately 2.8 times that of the single type. Furthermore, the influence of the preset crack length on the cracking of the asphalt mixture was studied. It was found that the crack length only affected the cracking location of the model and did not affect the crack propagation path.

     

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