离散元法的沥青路面车-路动力学响应分析

为了分析车辆荷载作用下沥青路面结构的细观状态力学响应,建立了二自由度1/4车辆模型与多层路基路面耦合离散元模型,通过各结构层单轴压缩应力-应变试验与相同工况试验数据比较,经迭代运算得到路面离散元模型各结构层细观参数,应用试验得到的沥青路面细观参数建立多层路基路面模型,在离散元模型的上表面设定一定不平度,在一定速度作用下,1/4车辆模型在路基路面离散元模型上表面匀速移动,从而求解车辆动荷载作用下沥青路面各结构位移、应力等细观受力状态.进而改变1/4车辆模型的车体悬架刚度、悬架阻尼系数、轮胎刚度,轮胎阻尼系数,从而获得在改变车辆参数作用下沥青路面内部的应力变化规律.研究结果表明:基于离散元理论不但可以求得沥青路面在车-路相互作用下各层的应力与变形,而且还可以求得沥青路面各结构层颗粒流的变化趋势,在车辆移动荷载作用下,随着路基路面深度增加,各结构层颗粒流竖直方向动态位移与应力响应依次减少,其中上基层颗粒流动位移比上面层颗粒流动位移减少25%,下面层颗粒流竖向应力约为上面层颗粒流竖向应力的50%,水平方向上颗粒流既有压应力又有拉应力,变化比较复杂,上面层颗粒流水平方向主要承受压应力,其余结构层主要承受拉应力;增加轮胎与悬架刚度系数对模型颗粒流水平方向拉应力影响较大,增加轮胎与悬架阻尼系数对垂直方向颗粒流压应力与水平方向拉应力影响较小.

Dynamic Response Analysis of Vehicle-load on Asphalt Pavement Based on Discrete Element Method

In order to analyze the microscopic state mechanics response of asphalt pavement structure under vehicle load, the coupled discrete element model of a two-degree-of-freedom 1/4 vehicle model and a multi-layer subgrade-pavement was established. The results of the uniaxial compressive stress-strain test of each structural layer was compared with the experimental data under the same working conditions, and the microscopic parameters of each structural layer of the discrete element model was obtained through iterative operations. A multi-layer subgrade-pavement model was established by using the microscopic parameters of an asphalt pavement, and a certain degree of unevenness was set on the upper surface of the discrete element model. The 1/4 vehicle model was moved on the discrete element model of the pavement under a certain speed, and the response of various structures of the asphalt pavement (such as displacement and stress) were obtained under the dynamic load of the vehicle. Further, by varying the body suspension stiffness, body suspension damping coefficient, tire stiffness, and tire damping coefficient of the 1/4 vehicle model, the changes in internal stress of asphalt pavements under the influence of different vehicle parameters were obtained. The research results show that it can not only obtain the stress and deformation of each layer of asphalt pavement under the interaction of vehicle and road based on the discrete element theory, but also obtain the trend of particle flow in each structural layer of asphalt pavement, under the action of vehicle moving load. The dynamic displacement and stress response of the particle flow in each structural layer decrease with increase in the subgrade-pavement depth. The dynamic displacement of the upper base particle flow is less than 25% of the dynamic displacement of the upper layer particle flow, and the vertical stress of the particle flow in the lower layer is 50% of the vertical stress of the particle flow in the upper layer. The particle flow is subjected to both compressive and tensile stresses in the horizontal direction, and the horizontal stress changes are complicated. The particle flow in the upper layer is mainly subjected to compressive stress in the horizontal direction, and the rest of the structural layer material is mainly subjected to tensile stress. The horizontal tensile stress of the model particles has considerable influence in increasing the stiffness coefficient of the tire and suspension, while the vertical pressure stress and horizontal tensile stress of the particle flow has little influence in increasing the damping coefficient of the tire and suspension.