| In recent years,with the rapid development of pumped storage,asphalt concrete has been widely used because of its good anti-seepage deformation ability.Asphalt concrete is a multiphase composite material composed of aggregates,asphalt matrix,holes,etc.Its complex mechanical response is caused by the randomness of microstructure morphology and distribution.The research of damage mechanism of asphalt concrete and the prediction of related properties need to be based on the characteristics of meso-structure.Most traditional researches regard asphalt concrete as homogeneous body,ignoring the influence of each component on asphalt concrete,resulting in the difference between theoretical research and practical situation.In this paper,the sectional image of asphalt concrete is obtained based on CT scanning technology,and the macro performance prediction and failure mechanism research are carried out considering the microstructure of each component in combination with fuzzy set theory,damage evolution theory and model reconstruction algorithm.This paper provides a new method for building a numerical model close to the real structure of asphalt concrete,and the research results preliminarily analyze the influence mechanism of the meso-structure on the macro performance.Firstly,the section image of asphalt concrete core sample based on actual engineering is obtained by CT scanning technology,and the CT number of the image is extracted by image processing software and model reconstruction algorithm.According to the difference of CT number,asphalt concrete is divided into aggregate,asphalt matrix(mortar),hole and interface.A numerical model close to the real structure of asphalt concrete is established in ANSYS software,and the actual micromorphologies of aggregate,asphalt matrix(mortar),holes and other internal structures are well restored.Secondly,based on the internal structure of each component that can be identified by the numerical model,the constitutive model is selected and the parameters are determined.It is determined that the aggregate element is the linear elastic constitutive model,the asphalt matrix element and the interface element are the elastic-plastic constitutive model,and the hole element has no constitutive model and does not participate in the numerical calculation.The model is constrained and loaded according to the macroscopic mechanical test conditions,and the real stress of the sample is simulated to complete the numerical test solution calculation.Finally,the damage evolution mechanism of the numerical model of asphalt concrete is analyzed based on the simulation test results.According to the displacement-controlled loading,the stress concentration around the holes in the asphalt concrete sample is obvious,and the cracks often start here.During the process of crack propagation,the cracks mainly proceed along the interface with weak strength in the sample.When failure occurs,the development trend of microcracks in interfacial unit is much greater than that in asphalt matrix unit.The interface element is most easily destroyed to form microcracks,and then the microcracks extend to the asphalt matrix element,and plastic damage occurs to the model. |
