不同荷载模式作用下饱水沥青路面结构动力响应对比分析

Contrastive Analysis of Dynamic Response of Saturated Asphalt Pavement Structure under Different Loading Modes

目的探讨不同荷载模式下饱水沥青路面结构的水损害机理,改进和完善沥青路面防排水设计方法.方法基于沥青混合料的渗透试验和多孔介质流固耦合理论,采用非线性有限元方法,对比分析了碗形分布荷载和均布荷载作用下饱水沥青路面结构各力学场量的变化并进行数值模拟分析.结果在均布荷载和碗型荷载两载模式下,饱水沥青路面结构内部各力学场量的时程变化特性相类似,均随着车轮动荷载的作用过程表现出波动性和滞后性,孔隙水压力对体积应力和应变影响较大.与均布荷载下计算结果相比,碗形分布荷载作用时上面层内最大正孔隙水压力高0.18倍,下面层底部最大水平拉应力和最大水平拉应变分别高0.14倍和0.15倍,中面层底部最大竖向压应力和基层底部最大竖向拉应力分别高0.23倍和0.03倍,路表最大竖向位移高0.07倍,面层内最大剪应力高0.05倍.结论在碗形分布荷载作用下,饱水沥青路面更容易产生水损害.采用接近于实际车轮荷载的碗形分布荷载模式来开展饱水沥青路面动力响应分析更为合理.

The mechanism of water damage of saturated asphalt pavement structure under different loading modes was discussed to improve and perfect the design method of waterproofing and drainage for asphalt pavement.Based on the permeability test of asphalt mixture,the changes of the mechanical field parameters among the saturated asphalt pavement structure under uniform distribution load and bowl-shaped distribution load were simulated and analyzed by using non-linear finite element method according to the theory of porous media.Stimulating results show that the change rules of the mechanical field parameters among the saturated asphalt pavement structure under bowl-shaped distribution load are similar to those under uniform distribution load,and mechanical field parameters of asphalt pavement structures show fluctuation and hysteresis with vehicle load under both loading modes,pore water pressure has a significant impact on volume stress and volume strain.Compared with the calculating results which is under uniform distribution load,the calculating results under bowl-shaped distribution load show the positive pore pressure peak in pavement surface course is 0.18 times higher,and the peaks of horizontal tensile stress and tensile strain at the bottom of the following layer are 0.14 and 0.15 times higher respectively,and the peaks of vertical tensile stress at the bottom of intermediate courses of asphalt pavement and the peaks of vertical tensile stress at the bottom of the basement are 0.23 and 0.03 times higher respectively,the peaks of vertical displacement on the surface of asphalt pavement is 0.07 times higher,the peaks of shearing stress in surface course is 0.05 times higher.So,the water damage take place more easily under bowl-shaped distribution load.It is more reasonable to analyze the liquid-solid coupling effect for saturated asphalt pavement structure by using bowl-shaped distribution load.