Fu Jiancun, Shen Aiqin
School of Highway, Chang'an University, Xi'an 710064, China.
Shandong Transportation Institute, Jinan 250000, China.
Materials (Basel). 2022 Jan 6;15(2):414. doi: 10.3390/ma15020414.
In cold regions, many types of structural damages are caused by the frost heaving of asphalt pavements. Hence, it is important to quantitatively determine the frost-heaving effect of asphalt pavement using a mechanical method to control frost-heaving damage. In this study, first, the internal voids of the asphalt mixture were regarded as a single void, and the water phase transition generating the freezing water in the voids was simulated using a simplified hollow sphere model to create a uniform internal pressure. Second, the prediction equation of the equivalent linear expansion coefficient was proposed by taking the phase transition of water in the saturated asphalt mixture voids into account. A step function was used during the phase transition of water to determine the sudden change in the equivalent linear expansion coefficient, heat capacity, density, and thermal conductivity. Finally, the typical cooling conditions were simulated with the water phase transition and the nonwater phase transition. The experimental results showed that the proposed model could accurately simulate the effect of frost heaving. Higher stress and strain were generated on the surface and in the interior of the pavement, and the positions of maximum stress and strain occurred on the pavement surface under the frost-heaving conditions. The compressive strength of the asphalt mixture in a uniaxial compression test is about 4.5-6 MPa with a single freeze-thaw cycle. Furthermore, when frost heaving occurs on the asphalt pavement between 5.8 and 6.5 MPa, the numerical simulation method can be used to calculate the internal stress of the structure, which found that the compressive stress under the frost-heaving condition was the same magnitude as the compressive strength under the freeze-thaw testing condition.
在寒冷地区，沥青路面的冻胀会导致多种类型的结构损坏。因此，采用力学方法定量确定沥青路面的冻胀效应对于控制冻胀损坏至关重要。在本研究中，首先，将沥青混合料的内部空隙视为单个空隙，并使用简化的空心球体模型模拟空隙中产生冻结水的水相转变，以产生均匀的内部压力。其次，考虑饱和沥青混合料空隙中水的相转变，提出了等效线性膨胀系数的预测方程。在水的相转变过程中使用阶跃函数来确定等效线性膨胀系数、比热容、密度和热导率的突然变化。最后，模拟了有水相转变和无水相转变的典型冷却条件。实验结果表明，所提出的模型能够准确模拟冻胀效应。在路面表面和内部产生了更高的应力和应变，并且在冻胀条件下，最大应力和应变的位置出现在路面表面。在单冻融循环下，沥青混合料在单轴压缩试验中的抗压强度约为4.5 - 6MPa。此外，当沥青路面在5.8至6.5MPa之间发生冻胀时，可使用数值模拟方法计算结构的内部应力，结果发现冻胀条件下的压应力与冻融试验条件下的抗压强度大小相同。
