半刚性基层沥青路面反射裂缝形成试验及扩展机理研究

基于应变水平进行道路结构起裂层位预估并应用断裂力学理论阐述裂缝形成及扩展原因，采用室内试验测试沥青路面各结构层的极限弯拉应变，研究荷载作用下半刚性基层沥青路面裂缝形成及扩展机理。在试验路段的各层位布设XYJ-2型应变传感器，监测道路结构的应变规律。结果表明:土基回弹模量较低时，原始开裂点在基层及底基层发生；裂缝尖端的应力强度因子均高于材料的断裂韧度，原始裂缝将会由于荷载作用而持续扩张，直至形成贯通裂缝。

Test Study on Formation of Reflection Crack in Semi-rigid Base Asphalt Pavement and the Crack Expanding Mechanism

The initial horizon of cracking in the road structure was predicted depending on the strain level, and by use of fracture mechanics theory, the formation and expanding causes were described. The formation and expanding mechanism of cracks in semi-rigid base asphalt pavement under the action of load were studied. Then the laboratory test was carried out to measure the ultimate bending strain of each structural layer of the asphalt pavement and, in each horizon of the test section, XYJ-2 strain sensors were arranged to monitor the strain law of the road structure. The result shows that, when the resilient modulus of soil foundation is low, the original point of cracking occurs at the base and sub-base layers; the stress intensity factors in the tip of cracks are greater than the fracture toughness of the material, and the original cracks will keep expanding under the action of load till through cracks are formed.