Numerical Simulation Of Failure Process In Concrete

Concrete is a heterogeneous material that is widely used in many engineering including structural engineering. Therefore, the investigation on its mechanical properties and fracture process is of a vital importance to mining engineering, underground engineering and engineering. The classic macroscopic mechanical models, which characterize the concrete as a continuum at macroscopic level and consider the test results of laboratory scale specimen as the mechanical properties of the material, could analyze the mechanical response of structures with greater size. In reality, the test results of laboratory that are generally called physical and mechanical parameters of material are average responses of a heterogeneous specimen with a certain size. This kind of homogenization is very important to the investigation of concrete structures and numerical analysis of engineering. But it is difficult to use these models to study the complete failure process caused by the initiation, propagation and coalescence of cracks when subjected external loading. At present, international investigations on the mechanical properties of concrete are beginning to transfer from the classic macroscopic mechanical level to a minor level, i.e. mesoscopic level, and a lot of mesoscopic mechanical models had been proposed. But these models are not perfect to some degree. In China, these kinds of research are very few.In this paper, a mesoscopic numerical model -beam-particle model that can simulate the fracture of concrete is proposed when the concrete is represented based on its meso- structures. In order to reflect the heterogeneity of concrete at mesoscopic level, the concrete is assumed to be a three-phase composite composed of matrix, coarse aggregates (and bond interface between them. Three types of beam element (reinforcing beam element, matrix beam element and interface beam element) and two kinds of particle (reinforcing particle element and matrix particle element) are used to simulate the mechanical properties of concrete, which randomly allocated according to Weibulldistribution to reflect the initial heterogeneity of concrete at the meso-scale level.The proposed model-beam-particle model is validated to simulate some routine tests of concrete which including uniaxial compressive test and uniaxial tensile test toprove that the numerical model can effectively to describe the complete failure process caused by the initiation, propagation and coalescence of cracks. The influence of the meso-mechanical properties to the macroscopic failure behavior is discussed in this paper.The proposed model is employed to simulate the dynamic failure process of concrete under impact loading, and analyse the failure behavior of concrete with different impacting velocity.Some applicable and perfect meso-models are summarized and compared in this paper as a reference to all researchers.