3D simulation of longwall-gateroad interaction in close coal seams

Purpose. To establish the regularities governing the evolution of the stress–strain state of a rock mass during mining operations in closely spaced coal seams with weak surrounding rocks, typical of the Western Donbas conditions, taking into account the spatial and temporal interaction between longwall faces and development gateroads. Methodology. The stress–strain state of the rock mass surrounding both longwall and development workings is determined using the finite element method (FEM). The study emphasizes the combined use of both two-dimensional and three-dimensional computational schemes, as well as different deformation models. In particular, a three-dimensional elastic FEM model is employed to simulate the spatial interaction between the longwall face and the gateroad; a two-dimensional elastoplastic FEM model based on the generalized Hoek–Brown failure criterion is used to analyze the stress state in the gateroad cross-section. A comprehensive approach is proposed, involving the consistent integration of these models within a unified numerical modeling framework, enabling a more accurate representation of the spatial–temporal evolution of mining operations and the interaction between excavations. Findings. The study reveals the regular patterns of increasing stress concentration within the rock mass located between the advancing faces of the longwall and the gateroad, which move toward each other at different horizontal levels (coal seams). A critical distance between the longwall face and the gateroad face has been identified, at which the destructive influence of the upper seam longwall on the lower seam gateroad begins to manifest. Based on the numerical modeling results, a relationship has been established between the extent of the plastic zone in the roof and the decreasing distance between the advancing faces in closely spaced coal seams. Originality. By combining two-dimensional and three-dimensional computational approaches, as well as integrating elastic and elastoplastic Hoek–Brown models, new regularities of the interaction between a longwall face and an underlying gateroad have been identified. These include the evolution of stress concentration, expansion of plastic zones, increase in displacements, and growth of internal forces in steel arch support elements. Practical value. The established regularities can be applied in the design of mining operations under similar geological conditions, for the development of support design guidelines for development gateroad, and for improving regulatory documents governing mining in closely spaced coal seams.