水泥混凝土路面加铺沥青层结构应力分析

Stress analysis of asphalt layer on cement concrete pavement

为了指导旧路加铺工程合理设计,对加铺结构在交通荷载作用下的受力状态进行了分析。基于路面力学弹性层状体系理论,建立了旧路加铺路面的轴对称有限元模型。主要考虑交通荷载作用,分析了沥青加铺层层底拉应力、剪应力和旧水泥路面层底的拉应力等指标。考虑加铺层和应力吸收层模量的影响对路面结构的力学响应进行了分析计算。为了快速计算材料力学性能对路面结构受力的影响,基于数值计算结果给出一个路表弯沉和沥青加铺层底拉应力的简易计算公式。结果表明:在车辆轴载作用下,增设应力吸收层会减小路表弯沉、沥青层底拉应力、新旧层间的剪应力和水泥层底拉应力各项指标,对于改善路面结构受力状态有积极影响;随着沥青面层模量的增加,路表弯沉、沥青层底剪应力和水泥层底拉应力都趋于减小,但是沥青层底拉应力会增大。由此建议在旧水泥路面加铺沥青面层设计时,应适当选用高模量的沥青混凝土材料,可以缓解路面新旧层之间的剪切脱层破坏,进而延长旧路改造路面的服役寿命。

In order to guide the reasonable design of the old road paving project, the stress of the overlay structure under the traffic load is analyzed. Based on the theory of elastic layered system of pavement mechanics, an axisymmetric finite element model of paved roads is established. Considering the traffic load effect mainly, the indexes such as the bottom tensile stress, shear stress and tensile stress of the old cement pavement layer are analyzed. Considering the influence of the additive layer and the stress absorption layer modulus, the mechanical response of the pavement structure is analyzed and calculated. In order to calculate the influence of mechanical properties of the material on the stress of the pavement structure, a simple calculation formula for the road surface deflection and the underlying tensile stress of the asphalt overlay is given based on the numerical results. The results show: under the axle load of the vehicle, adding a stress absorption layer will reduce the deflection of the road surface, the tensile stress of the asphalt layer, the shear stress of asphalt layer bottom and the tensile stress of the cement layer, which has a positive impact on improving the stress state of the pavement structure;with the modulus of the asphalt surface layer increases, the road surface deflection, the asphalt layer bottom shear stress and the cement layer bottom tensile stress tend to decrease, but the tensile stress increases. Therefore, it is suggested that when designing the asphalt surface layer on the old cement pavement, the high modulus asphalt concrete material should be properly selected, which can effectively alleviate the shear delamination damage between the old and new layers of the pavement, and extend the service life of the old road reconstruction pavement structure is extended.