The complexity of geological structures significantly impacts both mining production efficiency and operational safety, making its quantitative assessment a core issue in ensuring coal’s safe production and coalbed methane development. Focusing on the Wugou Coal Mine in Anhui Province, which exhibits multi-phase tectonic superposition, modification, and relatively complex structural characteristics, this study integrates stereographic projection analysis, fractal theory, and multiple structural curvature methods to quantitatively characterize structural types and evaluate complexity. The results show that the Wugou Coal Mine has undergone four main stages of tectonic deformation since the formation of the coal seam. The superposition and modification of tectonic events of different periods and properties have led to a complex structural pattern. The fractal dimension effectively characterizes the development degree and distribution density of faults. Structural curvature not only intuitively reflects the deformation extent of fold bending and fault separation, but also provides valuable insights into the structural types, structural positions, and the characteristics of superimposed folds. By combining the strengths of fractal analysis and curvature characterization, a fractal-curvature integrated evaluation model was developed to assess structural complexity. This model facilitates a high-resolution quantitative evaluation, delineating the geological structures of the Wugou Coal Mine into zones of extremely complex, complex, moderately complex, and simple structures. The findings not only provide accurate geological guidance for mine design and hazard prevention but also offer a quantitative evaluation methodology for the optimal selection of favorable areas for coalbed methane development.

The Yushupo Coal Mine in the Ningwu Coalfield is characterized by well-developed faults and pronounced folds, making it a representative site for testing a comprehensive structural evaluation model. Based on a systematic analysis of the structural deformation, an integrated fractal and curvature analysis is used to evaluate faults and analyze structural curvature and to establish a comprehensive quantitative evaluation model combining both methods. The results show that fault structures and their associated and derived folds together determine the tectonic deformation characteristics and structural complexity of the study area. Using refined evaluation unit grids, a high-precision fractal quantitative characterization of fault distribution density is achieved. High-value zones are concentrated in banded and beaded patterns in areas of dense fault development and fault intersections, but this method cannot identify fault throw or the degree of fold deformation. Structural curvature effectively reflects fold curvature and fault throw, with its absolute value increasing with both. The NE-trending high-value or low-value curvature belts can precisely indicate fold cores and areas near fault planes where structural deformation is strong. By utilizing the complementary characteristics of fractal dimension and mean curvature, a joint quantitative characterization of fault scale and fold deformation is achieved, effectively overcoming the limitation that a single fractal parameter cannot reflect fault throw and fold deformation and is easily disturbed by local small faults. Based on this comprehensive evaluation model and combined with structural genetic analysis, three zones are recognized in the study area: the northern NE-trending high-steep monocline zone, the central box-shaped hinge NE-trending fault zone, and the southern EW-trending steeply dipping fault block zone. The evaluation results facilitate risk assessment of gas outbursts and water inrushes and provide a geological basis for targeted mitigation measures across different structural zones.