MACRO-MICRO SCALE TENSILE STRENGTH CORRELATIONS FOR PARTICLE-DEM BASED ROCK MODELS

The discrete element method (DEM) numerical model has gained significant attention from scholars in the field of rock mechanics research due to its ability to capture both macroscopic and microscopic mechanical characteristics of natural rocks. However, researchers face challenges when it comes to scale bridging and parameter calibration in numerical simulation studies based on DEM. Furthermore, the absence of a unified and widely accepted quantitative analysis method adds to these challenges. To address these issues, we conducted a comprehensive study using a DEM model consisting of circular particles arranged in a regular pattern. The aim was to analyze the mechanical correlation between microscopic contact failure modes and macroscopic tensile strength. Our findings indicate that the macroscopic tensile strength of rock specimens is influenced by the underlying microscopic contact failure modes. These failure modes are affected by various factors including contact tensile strength, contact shear strength, contact normal stiffness, contact tangential stiffness, particle size, and arrangement. Through rigorous theoretical analysis and extensive numerical simulations, we proposed four microscopic failure modes along with corresponding theoretical formulas for calculating the macroscopic tensile strength. To validate the effectiveness of these formulas, we applied them to DEM models of randomly arranged particles. By adopting a microscopic perspective, we uncovered the underlying mechanisms of macroscopic tensile failure in DEM rock-like materials and established a correlation for the parameters governing macroscopic tensile strength. The validity of our established correlation formulas was successfully verified through a large number of random numerical simulation results. This work serves as an important reference for researchers involved in selecting and calibrating parameters for simulating brittle materials such as rocks and concrete using particle-based DEM numerical models. By providing insights into the microscopic behavior of materials, this study contributes towards enhancing the accuracy and reliability of DEM simulations in the field of rock mechanics research. © 2024 Chinese Society of Theoretical and Applied Mechanics. All rights reserved.