考虑砂浆随机分布的多孔沥青混合料黏附/ 黏聚失效行为

A meso-scalc finite element modeling method for incorporating the random distribution of mortar was proposed to obtain a more realistic adhesion/cohesion failure behavior of porous asphalt concrete (PAC). The actual meso-structure and mortar distribution of PAC were quantified by using X-ray CT scanning and image processing technology, and the random distribution characteristics of mortar were evaluated. The adhesion/cohesion properties of mortars with different thicknesses were evaluated by pull-off test that can accurately control the thickness of mortar, and the cohesive zone model parameters corresponding to different thicknesses of mortar were determined. Zero-thickness cohesive elements were embedded at the mortar-aggregate interface and within the mortar, and corresponding model parameters were assigned to the cohesive elements based on the mortar thicknesses in different regions of PAC. Finally, a meso-scale finite element model considering mortar random distribution (Model A) was built to study the meso-scale evolution process of PAC adhesion/cohesion failure behaviors. Research results indicate that it is recommended to divide the specimens into 36 parts to characterize the random distribution characteristics of mortar. Mortar thickness has significant influences on PAC adhesion/cohesion properties, failure modes, and cohesive zone model parameters. Adhesion failure is observed when the mortar thickness is less than 0. 9 mm or between 1. 2-1. 8 mm, while adhesion-cohesion mixed failure occurs when mortar thickness exceeds 1. 9 mm, and other mortar thicknesses result in cohesion failure. Adhesion/cohesion strength increases with increasing mortar thickness in the same failure mode. Compared with the meso-scale finite element model without considering mortar random distribution (Model B), the crack initiation points of Model A and Model B are both adhesion failures, but failure locations are different. Model B primarily exhibits a single adhesion failure, while Model A demonstrates multiple adhesion/cohesion failure behaviors, which is more consistent with field complex adhesion/cohesion failure behaviors. The random distribution of mortar has significant influences on the adhesion/cohesion failure process, stress distribution, and crack propagation of PAC. Therefore, considering the random distribution of mortar can more accurately identify the weakest position of PAC adhesion/cohesion failure, and increasing the mortar thickness can delay the evolution of adhesion/cohesion failure. 3 tabs, 17 figs, 40 refs.