不同沥青混凝土路面结构的抗裂性能对比分析

Comparative Analysis of Crack Resistance Performance of Different Asphalt Pavement

反射裂缝是半刚性基层沥青混凝土路面的主要病害之一,通过在半刚性基层和沥青混凝土面层之间分别加入级配碎石、低剂量水泥稳定级配碎石和沥青碎石,研究其对反射裂缝的影响。从断裂力学的基本原理出发,应用有限元软件建立三维有限元模型,在裂纹尖端创建奇异单元,分析了不同路面结构应力强度因子随裂纹长度的变化规律。应用广义Paris公式,对各种路面结构疲劳寿命进行了预估,结果表明:级配碎石或低剂量水泥稳定级配碎石层的加入可有效抑制半刚性基层反射裂缝的扩展,但其会明显增加沥青混凝土层弯拉疲劳开裂的可能性;沥青碎石层的加入对减少沥青混凝土面层剪切型和弯拉型开裂都具有良好的作用。

The reflective cracking is one of the main distresses of semi-rigid base asphalt pavement. To study the method of alleviating this kind of distress, the graded crushed stone, low dose of cement stabilized graded crushed stone and asphalt macadam are respectively added between the semi-rigid base and asphalt concrete. Based on the fracture mechanics, a three-dimensional finite element model is established with the finite element software. In the model, the singular elements are created at the crack tip. The stress intensity factors of different structures are calculated to analyze their changes along with the variation of the cracking length. The Generalized Paris Law is adopted to predict the fatigue lives of all kinds of pavement structures. The results show that： the graded crushed stone and low dose of cement stabilized graded crushed stone can efficiently prevent the propagation of reflective cracking in semi-rigid base asphalt pavement, but they will also increase the possibility of flexural-tensile type fatigue cracking of asphalt layer. Asphalt macadam layer has good effects on the reduction of flexural-tensile type cracking and shear type cracking of asphalt layer simultaneously.