COUPLED FEM-DEM ALGORITHM FOR NUMERICAL SOLUTION OF PROBLEMS OF ROCK MASS MECHANICS WITH UNDERGROUND STRUCTURES

This work proposes a coupled algorithm combining the Finite Element Method (FEM) and the Distinct Element Method (DEM) to model the mechanical behavior of rock masses near deep underground structures. FEM is used to calculate the stress-strain state of the surrounding rock mass and to identify the limit state (LS) zones in the vicinity of the underground structure through the use of a complex limit state criterion. Within these zones, DEM is further applied to model the mechanical state of the discrete structure of the mass using deformable block elements, which makes it possible to accurately describe localized zones of continuity violation in the mass (failures, shear deformation, and rockfalls). The algorithm’s efficacy is demonstrated via numerical solutions of two classic geomechanical problems: stability assessment of a single excavation and collapse analysis during the longwall mining at potash mining deposits of the Republic of Belarus. Verification of modeling results with the field data showed an error margin of 5–17 % in quantitative terms with adequate qualitative repetition of the studied geomechanical processes. The advantages of the developed algorithm include consideration of rock mass heterogeneity (due to the use of discrete medium mechanics methods), saving computational and time resources during numerical calculations.