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根据疲劳破坏及断裂力学理论,通过室内三点弯曲疲劳试验回归得到加铺层及应力吸收层材料裂纹发生及扩展计算参数,建立有限元模型计算了临界荷位不同裂纹长度裂尖应力强度因子变化规律,进行含应力吸收层及不含应力吸收层的加铺层路面结构疲劳开裂寿命预估。结果表明:(1)在相同的应力水平下,加铺层材料的裂纹产生寿命显著低于应力吸收层材料,加铺层材料C值显著小于应力吸收层,m值显著高于应力吸收层材料;(2)采用三次多项式用来回归裂缝尖端应力强度因子与裂纹长度a的关系可获得较高精度;(3)采用应力吸收层将加铺层路面反射裂缝开裂总寿命提高了69%,应力吸收层可显著延缓反射裂缝的发生;(4)应力吸收层主要通过自身疲劳寿命及改善加铺层的受力状态从而提高加铺层的裂纹扩展寿命来实现反射裂缝延缓效果。
According to the theory of fatigue failure and fracture mechanics, crack initiation and propagation parameters of overlay and stress absorption layer were obtained by indoor three-point bending fatigue test. The finite element model was established to calculate the change of stress intensity factor at crack tip with different crack length The fatigue life prediction of overlay pavement structure with stress absorption layer and without stress absorption layer is carried out. The results show that: (1) At the same stress level, the crack life of the overlay material is significantly lower than that of the stress absorbing layer material, the overlay material C value is significantly less than the stress absorbing layer, the m value is significantly higher than the stress absorbing layer material ; (3) The third-order polynomial is used to regress the relationship between the crack tip stress intensity factor and the crack length a; (3) The stress-absorbing layer increases the total crack-cracking life of the overlay pavement by 69% Absorption layer can significantly delay the occurrence of reflection cracks. (4) The stress absorption layer can achieve the effect of retarding the reflection cracks by increasing its fatigue life and improving the stress state of the overlay, thereby increasing the crack propagation life of the overlay.