The Calibration Method for Microscopic Parameters in the Particle Flow Code Model of Rock-like Materials: A Semi-Analytical Lookup Table Approach

Abstract: This study explores the calibration method for microscopic parameters in Particle Flow Code models of rock materials. Initially, a theoretical derivation is employed to determine the influence mode of microscopic parameters on macroscopic responses based on the CBM model. This is followed by a series of numerical simulations to determine the fitting coefficients in the theoretical relationship. Finally, a specific operation steps for the Semi-analytic Lookup Table (SLT) method is established, based on the intrinsic connection between macroscopic and microscopic parameters. Research suggests：The tensile strength is linearly positively correlated with the contact normal bond strength (CNBS), and negatively correlated with the particle size ratio (PSR) and stiffness ratio (SR) in a nonlinear manner; Under uniaxial compression conditions, the ratio of contact bond strength (tangential/normal) (RCBS) has a significant impact on the micro-failure mode of numerical specimens; When the contact modulus (CM)is greater than or equal to 10 GPa, Poisson's ratio is only related to the stiffness ratio; The influencing factors of the elastic modulus are CM, SR, and PSR, and their fitting parameters vary linearly with the PSR;When RCBS is below 0.7, the cohesion is primarily determined by the contact tangential bond strength (CTBS), with minimal influence from CNBS. Conversely, when the ratio surpasses 1.4, the cohesion is determined by CNBS, with a weak contribution from CTBS. The internal friction angle is primarily influenced by the particle friction coefficient, while the stiffness ratio has a negligible effect within a range of 2 to 6. Lastly, calibration of microscopic parameters for sandstone confirms that the SLT method can achieve a rapid parameter calibration.