Effects of Contact Normal Bond Strength on Brazilian Tensile Strength by Particle Flow Code

Abstract

The Contact Bond Model (CBM) of Particle Flow Code (PFC) can effectively simulate the mechanical behaviours of rocks. The physical and mechanical parameters of CBM directly influence the results of the numerical simulation of rocks. To reveal the influence mechanism of the contact normal bond strength of the CBM on Brazilian tensile strength, this study proposes a numerical test model and calculation method for the Brazilian tensile strength. First, the theoretical relationship between the Brazilian tensile strength and the contact normal bond strength of the CBM was derived. Second, 70 groups (350) of PFC Brazilian disk numerical tests were designed, and a numerical model of the Brazilian tensile strength was established. Third, the effects of the contact normal bond strength on the Brazilian tensile strength under various ball radii and ball radius ratios were analyzed according to the PFC numerical simulation results, and the correctness of the theoretical relation was verified. Results demonstrate that the Brazilian tensile strength is significantly and linearly related to the contact normal bond strength and can be expressed as the product of the contact normal bond strength and the scale coefficient. The scale coefficient is affected by the geometric parameters of balls. The scale coefficient generally increases with the minimum particle size, whereas the change in the coefficient becomes irregular. Results reveal the physical significance of the PFC normal bond strength to a certain extent. The proposed method can determine the contact normal bond strength.