连续变温沥青路面车辙变形数值模拟

Numerical Simulation of Rutting Deformation of Asphalt Pavement at Continuous Variable Temperature

采用ABAQUS有限元软件建立三维半刚性基层沥青路面结构的温度场模型,输入某地区夏季高温1天24 h温度,考虑了沥青路面材料性质(弹性模量、蠕变参数)随温度变化的特征,进行持续变温的车辙变形模拟分析。主要研究高温时,路面在不同行车速度作用下,不同深度结构层竖向变形、剪切蠕变、压蠕变规律。结果表明:竖向变形、剪切蠕变、压蠕变值在整个行车道路横向范围内呈正负交替变化。不同层位的竖向变形、剪切蠕变、压蠕变变化规律不相同,但同一层位变化规律是一致的,都随着行车速度的降低而增加,而且发现当车速处于中低速(30~80 km/h)时,车速增大对竖向变形、剪切蠕变和压蠕变的减小程度均明显高于中高速(80~120 km/h)。路表位置轮载外侧边缘受到拉、剪切的综合作用,也验证了拉应力和剪应力作用下,轮胎轨迹外侧边缘容易出现纵向裂缝。而路表正最大剪切蠕变出现在左侧轮迹内侧右边缘,负最大剪切蠕变出现在右侧轮迹内侧左边缘。所以在路表处轮迹内侧边缘容易出现剪切破坏的裂缝。剪切蠕变、压蠕变主要出现在中面层(4~10 cm范围内)。在沥青路面设计时,上面层与中面层需要选择时间硬化蠕变模型中A,n参数变化对温度敏感性小的沥青混合料,以提高沥青路面的抗车辙能力。

The actual temperature field model of 3D asphalt pavement semi-rigid road base is established by ABAQUS finite element software. Inputting one day 24 hours temperature in a given area in summer, considering the characteristics of the asphalt pavement material property （ elastic modulus, creep parameters） changes with temperature, the rut deformation simulation analysis based on continuous variable temperature is conducted to research the rules of vertical deformation, shear creep and compressive creep of asphalt pavement with different depth structure layers at different vehicle driving speeds at high temperature. The result shows that （ 1 ） vertical deformation, compression creep, shear creep present positive and negative variations in the whole traffic road lateral range; （2） the change regularities of vertical deformation, compression creep and shear creep in different structure layers are not the same, but those in the same structure layer are consistent, i. e. , increasing with the decrease of driving speed, and when the vehicle s at medium and low driving speeds （30 - 80 km/h） , the decreasing degrees of vertical deformation, shear creep and compressive creep as the driving speed increases are significantly higher than those at high driving speeds （80 - 120 kin/h）; （3） on surface of pavement, both outer edges of wheel load position bear the comprehensive function of shear and tensile stresses, which also verified the outer edges of tire tracks are easyto appear longitudinal cracks under the action of tensile stress and shear stress ; （4） on surface of pavement, the maximum positive shear creep is in the inner right side edge of left tire track, the maximum negative shear creep is in the inner left side edge of right tire track, so the fracture of shear failure is easily to appear at inner edge of wheel track on surface of pavement ; （5） shear creep and compression creep mainly appear in the middle of surface layer （within the scope of d -10 cm）. When designing asphalt pavement, in order to improve rut resistance, the asphalt mixture that has the changes of A, n in time hardening creep model which are little sensitive to temperature should be chosen for upper layer and middle layer.