机场复合式高模量沥青道面结构优化设计

Structural Optimization Design for Airport Composite High Modulus Asphalt Pavement

旧水泥混凝土道面加铺沥青层后易出现轮辙、疲劳开裂等问题。本研究尝试将高模量沥青混凝土引入机场复合式道面,通过ABAQUS有限元软件建立复合式道面模型,分析高模量沥青混凝土设置于不同层位时道面各结构层力学响应的变化规律,确定合理的设置层位。研究加铺层厚度、模量对结构力学响应的影响程度,通过正交试验得到高模量沥青加铺层最优结构组合。结果表明:复合式道面中沥青加铺层的最大允许覆盖次数小于水泥混凝土板的最大允许覆盖次数,因此道面结构的疲劳寿命取决于沥青加铺层的疲劳性能,合理地选择高模量沥青混凝土在加铺层中的设置层位有助于改善道面的疲劳性能;沥青加铺层底面的拉应变可作为复合式道面的疲劳控制指标;和下面层的厚度与模量相比,中面层的厚度与模量对加铺层的力学响应影响更加显著;将高模量沥青混凝土设置在中面层或中面层+下面层可有效降低沥青层底面的拉应变与沥青层的最大剪应力,改善复合式道面的力学性能;与普通加铺层结构相比,高模量沥青加铺层的最优组合可减小34.81%沥青层底面的拉应变与26.91%沥青层的最大剪应力,降低结构层发生轮辙与裂缝病害的风险。研究成果为复合式道面结构设计补充了力学指标,并为在机场道面推广高模量沥青混合料提供了参考方案。

The old cement concrete pavement is prone to problems such as rutting and fatigue cracking after asphalt layer paving.This study attempts to introduce high modulus asphalt concrete into the airport composite pavement.The airport composite pavement model was established by using finite element software ABAQUS.The variation rule of mechanical response of each pavement layer was analyzed,when high modulus asphalt concrete was set in different layers,so as to determine the reasonable setting layer of high modulus asphalt concrete.Simultaneously,the influence of overlay thickness and modulus on structural mechanical response was studied.The optimal structural combination of high modulus asphalt overlay was obtained with orthogonal test.The result indicates that the maximum allowable coverage times of asphalt overlay is less than that of cement concrete slab in the composite pavement.The fatigue life of pavement structure depends on the fatigue performance of asphalt overlay.Reasonable selecting the layer of high modulus asphalt concrete in overlay is helpful to improve the fatigue performance of pavement.The tensile strain at bottom of asphalt overlay can be used as the fatigue control indicator of composite pavement.Compared with the thickness and modulus of lower layer,the thickness and modulus of middle layer have more significant effects on the mechanical response of overlay.The setting of high modulus asphalt concrete in middle layer or the middle layer+lower layer can effectively reduce the tensile strain at bottom of asphalt layer,and reduce the maximum shear stress of asphalt layer for improving the mechanical properties of composite pavement.Compared with the ordinary overlay structure,the optimal combination of high modulus asphalt overlay can reduce the tensile strain at asphalt layer bottom by 34.81%,reduce the maximum shear stress of asphalt layer by 26.91%,and reduce the risk of rut and crack diseases in structural layer.The study results supplement the mechanical indicators for the composite pavement structure design,and provide a reference scheme for the promotion of high modulus asphalt mixture in airport pavement.