级配碎石基层沥青路面合理沥青层厚度
Reasonable thickness of asphalt layer in graded crushed stone base asphalt pavement

为得到适用于级配碎石基层沥青路面的合理沥青层厚度，当级配碎石基层厚度为20 cm时，利用BISAR 3.0程序计算不同沥青层厚度（4~36 cm）路表和面层底部应变、路基顶面压应变、沥青面层和级配碎石基层内不同深度剪应力，进一步根据不同结构层的应力应变疲劳极限确定不同沥青层厚度级配碎石基层沥青路面结构疲劳开裂、永久变形和车辙的病害状况，根据路面结构使用性能和耐久性实现沥青层厚度的优选。为验证薄沥青层级配碎石基层路面结构力学响应和长期使用性能，采用足尺路面加速加载试验（APT），对5 cm沥青层厚度路面结构的力学响应、长期使用性能及病害特征进行验证。结果表明：当级配碎石基层厚度为20 cm时，沥青层不宜过薄，沥青层厚度？？h？？？？1＜5 cm时易产生过大的路表永久变形和自上而下的疲劳开裂；沥青层厚度为5~？？18 cm？？时，存在较大的面层层底拉应变、路基顶面压应变、沥青面层和级配碎石基层最大剪应力的不利受力组合；沥青层厚度？？h？？？？1≥34 cm时，可满足长寿命沥青路面的使用要求；若条件受限时，宜保证沥青层厚度？？h？？1？？≥18 cm;由APT试验结果可知，沥青层厚度为5 cm时，沥青层层底拉应变计算结果、路面结构剪应力计算结果与试验路实际使用状况基本符合，路面结构主要病害为车辙和永久变形，疲劳开裂并不明显，但路基顶面压应力计算值偏小，该值不宜作为路面结构设计依据。
In order to investigate the reasonable asphalt layer thickness for graded crushed stone base asphalt pavement, BISAR 3.0 program was adopted to calculate the strain at the surface and bottom of different asphalt layer thickness, the compressive strain on the top of the subgrade, the shear stress of different depth in the asphalt layer and graded crushed stone base when the thickness of base was 20 cm and the thickness of asphalt layer range was 4 to 36 cm. The fatigue cracking, permanent deformation and rutting distress on the graded crushed stone based asphalt pavement of different asphalt layer thickness were determined according to fatigue limit stress of different structural layer. And the optimization of the asphalt layer thickness was realized according to the usability and durability of pavement structure. In order to verify the mechanical response and long？？term performance of the graded crushed stone based pavement structure of thin asphalt layer, the full？？scale accelerated pavement testing (APT) was used to verify the calculation of mechanical response, long？？term performance and disease characteristics of the 5 cm asphalt layer pavement structure. The results show that when the thickness of graded crushed stone base is ？？20 cm？？, the asphalt layer should not be too thin, and when the thickness of the asphalt layer is less than 5 cm, the permanent deformation of the road surface and the fatigue cracking from top to bottom are easy to occur. The pavement is more prone to experience excessive permanent deformation and fatigue cracking when the asphalt layer thickness is less than 5 cm. When the asphalt layer thickness ranges from 5 to 18 cm, there is an unfavorable combination of large tensile strain on the bottom of asphalt layer, compressive strain on the top of subgrade, and maximum shear stress in the asphalt surface layer and the graded crushed stone base. The requirement of the perpetual asphalt pavement can be satisfy when the asphalt layer