Calibration method of meso-parameters of PFC2D flat-joint model

Abstract

  The rapid and accurate calibration of meso-parameters is of utmost importance for the correct simulation of mechanical properties of a rock in PFC.Thus far, the calibration methods for flat-joint model (FJM) meso-parameters have not considered the bonding ratio, ϕ_b, which significantly influences both Poisson's ratio and compression-tension ratio, and the coefficient of variation of bonding strength, R_sd, which significantly influences rock strength and difficulty of crack formation.Crack initiation strength, σ_ci, is a macro-parameter that has not been considered;however, it is an important index to judge the damage range of the surrounding rock.Therefore, ϕ_b, R_sd, and σ_ci were included in parameter calibration study.Orthogonal numerical tests were conducted to study the correlation between the eight meso-parameters of the FJM and the six macro-parameters of the rock.The fitted relationships between each of the macro-parameters and main meso-parameters were determined;furthermore, an analysis of the trend relationships between the macro- and meso-parameters was conducted.Based on the above, a FJM meso-parameters calibration method was proposed, and the calibration method was used to calibrate the meso-parameters of the gneiss granite, whose macro-parameters have already been experimentally determined.The calibrated numerical model was used to perform a series of numerical experiments, and the calibration method is verified to be feasible because the results of the numerical experiments are close to those of the physical experiments.