沙漠公路倒装式沥青路面力学性能研究

Research on Mechanical Properties of Inverted Asphalt Pavement for Desert Highway

摘要:

沙漠地区昼夜温差大，年最热月、最冷月极端气温均较为明显，公路产生温缩、干缩开裂病害难以避免，造成路面结构强度下降。基于此，提出沙漠公路倒装式沥青路面结构试验段方案，利用粒料类柔性基层防止或延缓沥青路面反射裂缝。根据《公路沥青路面设计规范》（JTG D50—2017）中路面结构验算方法，采用HPDS计算软件，分析研究倒装式沥青路面级配碎石层厚度、模量对路面结构力学性能影响以及路面结构的疲劳衰减性能。结果显示：级配碎石层过厚，容易造成沥青层的弯拉疲劳开裂，且路表弯沉值小幅减小，而厚度过小，不宜压实，容易产生离析，应以15~18 cm为宜；级配碎石层回弹模量越大，半刚性层疲劳开裂和沥青混合料层疲劳开裂对应的累计当量轴次以及沥青混合料层永久变形量均增大，半刚性层层底拉应力明显减小。

Abstract:

The desert area has a large temperature difference between day and night, and the extreme temperatures in the hottest and coldest months of the year are relatively obvious. It is hard to avoid the temperature shrinkage and dry shrinkage cracking of highway, resulting in a decrease in the strength of the pavement structure. Based on this, the scheme of inverted asphalt pavement structure test section of desert highways is proposed. The flexible base layer of granular material is used to prevent or delay the reflection cracks in the asphalt pavement. According to the pavement structure check calculation method in Specification for Design of Highway Asphalt Pavement (JTG D50—2017), the HPDS calculation software is used to analyze and study the influence of the thickness and modulus of the graded gravel layer of the inverted asphalt pavement on the mechanical properties of the pavement structure and the fatigue attenuating properties of pavement structure. The results show that the graded gravel layer too thick is easy to cause the flexural fatigue cracking of the asphalt layer. If the deflection value of the road surface decreases slightly and the thickness is too small to be compacted, the segregation is easy to occur, and 15~18 cm should be suitable. The larger the rebound modulus of graded gravel layer is, the greater the cumulative equivalent axis times corresponding to the fatigue cracking of the semi-rigid layer and the fatigue cracking of the asphalt mixture layer are and the permanent deformation of the asphalt mixture layer is. The tensile stress at the bottom of the semi-rigid layer decreases significantly.