Three-dimensional discrete element model of crack evolution on the crack tip with consideration of random aggregate shape

In this paper, a method for concrete three-dimensional random polyhedral aggregate mesostructure is proposed. Moreover, a concrete discrete element fracture mesoscopic analysis model is established. The mesoscopic destruction mechanism of three-dimensional fracture of concrete three-point bending specimens is investigated. Three-dimensional evolutionary extension morphology of crack tip and fracture process zone (FPZ) of small-size concrete specimens in an indoor laboratory is simulated and analyzed. Furthermore, the entire fracture process of concrete specimens is investigated. The three-dimensional morphology of the crack tip and fracture process zone is analyzed via normal distribution statistics. Consequently, the size effect law of crack extension and fracture process zone evolution is derived. The fracture process of actual large-scale concrete specimens is predicted based on deficiencies of small-scale specimens in indoor tests. The results show that the proposed model is an effective method to characterize the three-dimensional fracture process of concrete and predict mechanical properties of large-scale specimens in actual structures.