基于永久变形试验的沥青混合料损伤分析

为分析沥青混合料的损伤特性,进行了两种沥青混合料的重复荷载永久变形试验,采用Kachanov损伤律推导了沥青混合料的损伤演化方程,并根据试验结果确定了损伤参数.结果表明,耦合损伤的力学模型较好地描述了沥青混合料三阶段的变形特性.在荷载作用下,沥青混合料损伤单调增加,而接近破坏时损伤会急速发展;在较高的应力和温度条件下,损伤值较大,且损伤发展较快.荷载作用次数达到流动数时,2种沥青混合料的损伤值基本介于0.14～0.15之间,表明在永久变形的迁移期和稳定期同样存在损伤,只是损伤值较小,并且可以近似看成线性损伤,但将其忽略是不合理的.

Damage Characteristic of Asphalt Mixture by Permanent Deformation Test

In order to analyze the damage characteristic of asphalt mixture, repeated loading permanent deformation tests of two asphalt mixtures are conducted, and the damage parameters are obtained based on the test results and damage evolution equation deduced from the Kachanov damage raw. It is indicated that the mechanical model coupled with damage can well describe the whole three phase permanent deformation of asphalt mixture under repeated loading. The damage of asphalt mixture monotonously increases with loading cycles, and the damage increases rapidly at the moment when asphalt mixture is close to failure. The value is bigger at higher temperature and stress, and also it increases faster. When loading cycles reaches the flow number, the damage values of two asphalt mixtures are 0.14~0.15. It shows that damage also exists in the migratory and stationary phases and is approximately linear though its value is small. But, it is unreasonable to ignore the damage in these two phases.