Concrete Failure Process Simulation Considering The Influence Of Internal Material Interface

Concrete is generally regarded as a three-phase composite material integrating aggregate,cement mortar and an interfacial transition zone(ITZ)between them,in which the dispersion of the cement mortar and the interfacial transition zone is large,and the discreteness of the two manifests itself in the randomness of the material properties(modulus of elasticity,strength,etc.).When considering the randomness of material properties,the traditional stochastic mechanical characteristic model generally considers the material properties to follow the Weibull distribution,but neglects the influence of the materials in each phase of the concrete.In this paper,aiming at the limitations of the traditional stochastic mechanical characteristic model,the impact of aggregate size on the interfacial transition zone is incorporated into the traditional stochastic mechanical characteristic model.This study has important significance for the study of the traditional stochastic mechanical characteristic model.The differences in aggregate size based on the aggregates in this article will lead to different characteristics of the random distribution parameters of ITZ.Through the relevant existing experimental results,the relationship between aggregate size and the random distribution parameters of ITZ is obtained and ITZ is treated as a multilayer structure determines the stochastic distribution of material properties layer by layer to determine random distribution parameters,thereby establishing a mesoscopic model with stochastic mechanical properties that takes into account various effects of aggregate size on ITZ.When establishing a mesoscopic model of stochastic mechanical properties that takes into account multiple effects of aggregate size on the ITZ,the PYTHON language is integrated with the APDL language to increase the modularity and modeling efficiency of the program.In addition,based on the established mesoscopic model,the concrete failure process was studied.PYTHON repeatedly used ANSYS calculation results to obtain a unit destruction database to improve the computational efficiency of the model.Using the established mesoscopic model of stochastic mechanical properties to simulate the tensile test and flexural test of concrete,the correctness of the model was verified and the mechanism of initiation and propagation of concrete cracks was revealed.Finally,the micro-blow-off effect was taken into account in the stochastic mechanical properties model considering the effects of aggregate size on ITZ.Through an example analysis,it is proved that the meso-mechanical model with stochastic mechanical properties considering the various influences of aggregate size on ITZ can better explain the failure mechanism of actual concrete specimens.It also shows that the multi-layer ITZ structure has advantages that are unmatched by a singlelayer ITZ structure.The mesoscopic model considering the effects of micro-bleeding water and aggregate size on ITZ can better explain the effect of micro-bleeding water on the strength and failure process of concrete specimens.The proposed numerical model for stochastic mechanical properties provides an effective means for investigating the mechanical properties of mortar and interfacial transition zone in concrete materials.