Abstract:In order to study the transmission and distribution of contact force chain in asphalt mixture under different stress modes of tension, compression, bending and shearing, clear different aggregate mortar components resistance load in the respective levels of contribution, based on industrial computed tomography (CT) and digital image processing method for aggregate particle model, using software PFC3D constructed SMA13 gradation of asphalt mixture of 3D digital specimen, and virtual tests were carried out under different stress modes. The transfer and distribution characteristics of contact force chain inside asphalt mixture and the distribution of contact force composition of different components of mortar aggregate were visualized and quantitatively analyzed. At the same time, the force chain probability was used as a quantitative index to analyze the distribution characteristics of various contact force chains under different force modes. The results show that the three-dimensional digital model established by discrete element method can better simulate the low temperature mechanical behavior of asphalt mixture. In uniaxial compression mode, the ratio of all kinds of contact strong chains is the highest among the four stress modes. The interlocking extrusion between aggregates is the main factor to resist external load, and the contact force level transmitted by aggregates accounts for 69.9% of the total contact force. Under indirect tensile and semi-circular flexural loading modes, the proportion of the strong chain between the interior and interface of asphalt mortar is significantly higher than that between aggregate. The contact force transmitted by asphalt mortar accounts for 50.1% and 57.4% of the total contact force, respectively. The bond between asphalt mortar is the dominant factor to resist damage. In uniaxial penetration force mode, the proportion of strong chain between asphalt mortar and interface is slightly higher than that between aggregate, and the contact force transmitted by aggregate accounts for 64.7% of the total contact force. The ratio of strong and weak force chain can better reflect the load transfer capacity of different components of asphalt mixture under different stress modes. The results can provide theoretical basis for understanding the mechanical behavior of asphalt mixture from the perspective of meso-structure.
