沥青路面Top-Down裂缝的断裂力学分析

采用移动荷载模式,在有限元方法中利用动态模量主曲线和时间-温度位移因子来表征沥青混合料的力学性质,利用断裂力学的方法分析了温度、车速、裂缝长度和基层类型等对沥青路面Top-Down裂缝裂尖应力强度因子的影响.研究表明随着裂缝长度增加和温度降低,张开型应力强度因子(KⅠ)和剪切型应力强度因子(KⅡ)的峰值增加.行车速度对应力强度因子的作用频率有显著影响,较慢的行车速度会加速Top-Down裂缝的扩展.与采用粒料基层相比,采用半刚性基层可降低裂尖应力强度因子.随着温度升高和裂缝长度增加,KⅠ对裂缝扩展的贡献减小,而KⅡ的贡献逐渐增加.

Analysis of Top-Down Cracking of Asphalt Pavements Using Fracture Mechanics Approach

In this study, the effects of temperature, vehicle speed, crack length and base type on the stress intensity factor (SIF) at the tip of top-down cracking in asphalt pavements under moving load were evaluated by conducting fracture mechanics and finite element (FE) analyses. Dynamic modulus master curves and time-temperature shift factors were incorporated into the FE model to characterize the mechanical properties of asphalt mixtures. The results show the peaks of tensile type SIF (KI) and shear type SIF (KII) increase as crack length increases and temperature decreases. Vehicle speed has significant influences on the frequency of SIF and slow traffic loading can accelerate the propagation of top-down cracking. The use of semi-rigid bases in asphalt pavements can reduce SIF compared to granular bases. The contribution of KI to the propagation of top-down cracking becomes less significant, while that of KII becomes more evident when temperature and crack length increase.