均布荷载下横观各向同性沥青路面力学行为分析

Structural mechanics behavior analysis of cross-anisotropic asphalt pavement under distributed load

文章采用广义Maxwell模型描述沥青混合料面层的黏弹性,考虑碎石基层和土基的横观各向同性特征对路面结构力学行为的影响。在弹性假设条件下引入材料水平模量与竖直模量比值为变量,运用有限元方法建立路面结构三维有限元模型;通过模拟计算,对比分析均布荷载作用下碎石基层和土基各向同性与横观各向同性对各结构层应力和应变及路表弯沉值的影响,并对沥青路面服务寿命进行预估分析。分析结果表明:均布荷载作用下碎石基层的横观各向同性特征对路表弯沉影响较小,而土基横观各向同性特征对路表弯沉影响较大;路基顶部压应变受碎石基层及土基横观各向同性特征影响较大,而面层层底拉应变和基层底拉应力仅受碎石基层横观各向同性特征影响较大;沥青路面服务寿命受碎石基层横观各向同性特征影响较大,且在碎石基层各向同性时服务寿命最长。因此,在路面结构设计中应适当考虑基层和路基材料的横观各向同性特征。

Generalized Maxwell model was adopted to exhibit the viscoelastic property of asphalt mixture surface and the effect of cross-anisotropy characteristic of macadam base and soil subgrade on the mechanical behavior of pavement structure was analyzed. The level of anisotropy was defined as the ratio of the horizontal modulus to the vertical modulus. Three-dimensional finite element methods were applied to analyzing and comparing the stress and strain on each structure layer and surface deflection under distributed load in different levels of anisotropy. And then the service life of asphalt pavement was estimated. The analysis results show that the impact of cross-anisotropy characteristic of macadam base on the surface deflection is negligible, yet the influence of that of soil subgrade is big. The effects of cross-anisotropy characteristic of macadam base and soil subgrade on the structure stress emerge on the top of the subgrade as compression. However, the effects of cross-anisotropy characteristic of macadam base on the structure strain arise on the bottom of the surface course as tension, and on the structure stress arise on the bottom of the base course as tension. The service life of asphalt pavement is greatly influenced by the cross-anisotropy characteristic of macadam base, and the service life reaches to the peak value when macadam base has the properties of isotropy. Consequently the cross-anisotropy characteristic of macadam base and soil subgrade should be considered in pavement structure design.