Geomechanical Assessment of Rock Mass Stability Near Mined-Out Areas Using Numerical Modeling Data

Abstract

This study presents a geomechanical assessment of the stress-strain state of a rock mass near mined-out areas using numerical modeling. The aim of the research is to establish the patterns of stress redistribution and the development of inelastic deformation zones around a development working (excavation) depending on the relative distance to the stope L/B, where L is the distance to the stope and B is the excavation width. Numerical modeling was performed using the finite element method in the RS2 software package, applying the Hoek-Brown strength criterion. The parameters of the rock mass were determined based on the processing of initial laboratory characteristics using the RSData software. The stress concentration factor K and the development of inelastic deformation zones were considered as the main analysis indicators. It was established that the dependence of the stress concentration factor K and the parameters of inelastic deformation zones on the relative distance L/B exhibits a pronounced nonlinear character. At small distances (L/B < 5), intensive interaction between the stope and the development working is observed, accompanied by maximum values of the stress concentration factor (up to 1.85-1.87) and significant development of inelastic deformation zones due to the superposition of stress fields. With increasing distance between the workings, the intensity of their mutual influence gradually decreases, which is manifested in a reduction of the stress concentration factor and a decrease in the size of inelastic deformation zones. At L/B = 6-7, spatial separation of inelastic deformation zones begins, accompanied by a significant weakening of the mutual influence of the workings, which allows this range to be considered as a rational distance when designing their mutual arrangement. The minimum values of the stress concentration factor and the smallest sizes of inelastic deformation zones are achieved in the range of L/B = 12-14, which indicates stabilization of the stress-strain state of the rock mass. With a further increase in distance, the parameters practically do not change, and the mutual influence of the stope and the development working becomes insignificant. The obtained results make it possible to substantiate rational distances between development workings and stopes, ensuring increased rock mass stability and reduced geomechanical risks in underground mining.