冻融受荷协同作用下沥青混合料损伤模型研究

Research on the damage model of asphalt mixture under synergy action of freeze-thaw and loading

为研究寒区沥青路面抗冻融性能,借助细观损伤力学与宏观统计随机损伤理论,提出冻融变量、荷载变量及协同效应等概念,构建了冻融与荷载共同作用下的沥青混合料损伤本构关系和损伤演化方程,揭示冻融循环次数、应变及油石比影响下的沥青混合料冻融受荷损伤劣化机理.研究表明:寒区沥青混合料力学性能受冻融变量、荷载变量及协同效应影响显著,在冻融受荷协同作用下总损伤劣化呈非线性加剧趋势,沿冻融和受荷两条途径的损伤率演化规律迥异.冻融循环次数和油石比对损伤变量影响较大,但冻融次数超过20时,损伤变量和损伤率降幅均显著且趋于恒定.适当上浮最佳油石比,可有效改善寒区沥青混合料的抗冻融耐久性能.

Aimed at a study on the frost resistance of asphalt pavement in cold areas,three new conceptions are put forward,i.e.freeze-thaw variable,loading variable and the synergistic effect based on meso-damage mechanics and macroscopic statistical stochastic damage theory.The damage constitutive relation and damage evolution equation of asphalt mixture under coupling action of freeze-thaw and loading are established,and the damage degradation mechanism of freeze-thaw and loading asphalt mixture under the influence of freeze-thaw cycles,strain and bitumen aggregate ratio are revealed.It is shown that the mechanical properties of asphalt mixture in cold regions are greatly affected by freeze-thaw variable,loading variable and the coupling effects.The total damage of asphalt mixture presents obvious nonlinear characteristic under the coupling effect of freeze-thaw and loading.The damage evolution rate law along the way of freeze-thaw and loading is different.Freeze-thaw cycles and bitumen aggregate ratio have a great impact on the damage variables,but the reduced amplitude of damage variables and damage rate is significant,and it tends to be constant after 20 cycles.It is an effective way to increase the optimum asphalt aggregate ratio for improving the durability of asphalt mixture coupling of freeze-thaw and loading in cold areas.