基于层间模量比变化的沥青路面结构受力特性研究

Research on the Influence of Interlaminar Modulus Ratio on Mechanical Response of Asphalt Pavement Structure

为阐明不同材料结构层组合对半刚性基层沥青路面受力协调性的影响,选取典型的两层式沥青路面结构,以材料动态模量表征材料的刚度特征,计算分析基层与面层、基层与底基层、底基层与土基模量比变化情况下沥青路面的力学响应,探讨不同受力指标的变化特征及模量比变化对其的影响,并对比分析面层-基层层间接触条件改变前后沥青路面的力学响应。结果表明:面层-基层层间接触条件由完全连续状态劣化为光滑状态,沥青混合料层层底拉应变明显增大,而其他受力指标值则减小,不同于材料参数为静态模量时的路面结构力学响应。层间接触条件为完全连续状态时,半刚性基层沥青路面的受力协调性与不同结构层模量搭配密切相关,其中基层与底基层、底基层与土基模量比变化显著影响沥青路面结构内沥青混合料层层底拉应变、路基顶面竖向压应变和半刚性基层层底拉应力,而基层与面层模量比变化对沥青路面各受力指标的影响相对较小。基层与底基层、底基层与土基模量比过小易导致路面沥青混合料层发生裂缝、路基产生变形病害,模量比过大易导致半刚性基层发生裂缝、沥青混合料产生车辙病害;考虑沥青路面力学响应与受力协调性,两层式半刚性基层沥青路面基层与面层模量比宜在1.2~1.5之间、基层与底基层模量比宜在2.0~7.0之间、底基层与土基模量比宜在50.0~175之间。

To analyze the influence of different pavement structure with various materials on mechanical compatibility of asphalt pavement,the asphalt pavement structure with two-layer asphalt layer is selected,and the dynamic modulus is used to characterize the stiffness of pavement materials.The influence of base course to surface course modulus ratio,base course to subbase modulus ratio and subbase to soil base modulus ratio on mechanical response of asphalt pavement are discussed by the SHELL pavement design software BISAR 3.0,and the change characteristics of different stress indexes are analyzed.Meanwhile,the mechanical response of asphalt pavement is also discussed under different interlayer contact conditions between base course and surface course.The results show that when the interlayer contact condition between base course and surface course is deteriorated to sliding state,the tensile strain of asphalt layer bottom is significantly increased,but the other indicators are reduced.The mechanical compatibility of semi-rigid base asphalt pavement is closely related to modulus ratio of different structural layers when interlayer contact condition between base course and surface course is keeping interface continuous conditions.The change of base course to subbase modulus ratio and subbase to soil base modulus ratio have significant influence to tensile strain of asphalt layer bottom,vertical compressive strain at subgrade top and tensile stress at the bottom of semi-rigid base course,but the influence of base course to surface course modulus ratio on mechanical response of asphalt pavement is relatively small.Because the base course to subbase modulus ratio and subbase to soil base modulus ratio are too small,the asphalt mixture layer is very easy to crack and subgrade is very easy to distort.Meanwhile,the base course to subbase modulus ratio and subbase to soil base modulus ratio are too large,so the semi-rigid base is very easy to crack and asphalt mixture layer is very easy to rutting.Taking account of the mechanical response and mechanical compatibility of asphalt pavement,the base course to surface course modulus ratio in semi-rigid base asphalt pavement is recommended to 1.2 times~1.5 times,base course to subbase modulus ratio is recommended to 2.0 times~7.0 times,and subbase to soil base modulus ratio is recommended to 50.0 times~175 times.