Quantitative evaluation of mine structural complexity based on GIS-AHP-independence weight coefficient method: a case study of Guobei Coal Mine

Mine geological structures are the core elements controlling safe coal production and serve as the primary conduits inducing groundwater inrush accidents. To address the issues of incomplete evaluation indicators and single weighting methods in assessing mine structural complexity, this study takes Guobei Coal Mine as the research object and constructs a quantitative evaluation model for mine structural complexity based on the coupling of GIS, AHP, and the Independence Weight Coefficient Method. Four core indicators were selected: fault density, fault intensity, fracture fractal dimension, and fold planar deformation coefficient. The Analytic Hierarchy Process (AHP) was employed to determine subjective weights, while the Independence Weight Coefficient Method was used to determine objective weights, and the multiplicative synthesis normalization method was applied to achieve the fusion of subjective and objective weights. Spatial quantitative analysis and thematic map overlay were completed using ArcGIS, dividing the study area into four levels of structural complexity zones. The results indicate that: (1) fault intensity exerts the greatest influence on structural complexity (comprehensive weight of 0.4212), followed by the fold planar deformation coefficient (0.2894) and fracture fractal dimension (0.2516); (2) the structurally complex zones and relatively complex zones exhibit three concentrated distributions, located in the northeastern, central, and southern regions of the mine, respectively, the structurally complex and relatively complex zones accounting for 15.8% and 24.3% of the total mine area, respectively; (3) specifically in the Mining Areas 84 and 85, the structurally complex and relatively complex zones account for 21.1% and 41.0% of their respective district areas. Groundwater inrush points in the mining area are predominantly distributed within or adjacent to the structurally complex and relatively complex zones, with particular attention required for water inrush threats from roof fracture zones and fault intersections. The research findings accurately characterize the spatial differentiation of structural complexity in Guobei Coal Mine, providing targeted objectives and scientific geological basis for mine water hazard prevention and control. Simultaneously, the study offers methodological references for quantitative evaluation of structural complexity in mines with similar geological conditions, thereby enriching the theoretical and methodological framework of quantitative mine structural evaluation.