加铺应力吸收层的复合式路面开裂寿命预测

Cracking Life Prediction of Composite Pavement with Stress Absorbing Layer

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 fatigue damage and fracture mechanics, the calculation parameters of cracking initiation and propagation of overlay and stress-absorbing layer are regressively analyzed by indoor three-point bending fatigue test, the finite element model is developed to analyse the change of stress intensity factors at crack tip with different crack lengths under critical load, and fatigue cracking life prediction of overlay structure with and without stress-absorbing layer is conducted. The result shows that （ 1 ） the crack appearing life of overlay material of overlay material is significantly lower than that of stress absorption layer material under the same stress level, the C value of overlay material is higher than that of stress-absorbing layer, but the m value of overlay material is lower than that of stress-absorbing layer material ; （2） it can obtain high precision by taking cubic polynomial to make regression of the relation between stress intensity factor of crack tip and crack length; （3） the reflective cracking total life of overlay with stress absorbing layer is 69% higher than that of the overlay without stress absorbing layer, stress absorption layer can significantly postpone the occurrence of reflective cracking; （4） stress absorbing layer realizes the effect of improving the crack propagation life of overlay and then postponing the reflective cracking mainly by improve the stress status and its own cracking life.