Studying the evolution law of overlying rock fissures and predicting the development height of water-conducting fissure zones is the key to preventing roof water damage, protecting mine water resources, and realizing the safe and sustainable development of the mine. To study the overburden fracture evolution law of coal mining under aquifer conditions, the 1402 working face of Longwangzhuang Mine in Shaanmian Coalfield serves as the engineering background based on the Fractal Theory and similar simulation technology; this paper analyzes the fracture evolution of overburden rock and the development law of Water-Conducting Fracture Zone (WCFZ) during the advancing of working face, and further puts forward a model for the location discrimination of overburden fracture based on plate theory. The results indicate that post-mining, overburden rock failure assumes a trapezoidal shape, and fractures around the cutting hole and the side of the working face fully develop, while those in the middle of the goaf tend to compact. The distribution of the fracture network of mining strata at different advancing distances has good self-similarity, and the fractal dimension of the fracture network of overlying rock can be divided into three stages: ascending dimension, decreasing dimension, and stable phase. The II 1 coal seam fracture does not spread to the Sandstone Fissure Confined Aquifer. These findings provide strategic guidance for protecting mine aquifer water resources, preventing and controlling roof water inrush, and ensuring safe and sustainable production within the study area.

The western mining regions of China, known for shallow-buried and high-intensity mining activities, face significant ecological threats due to damage to loose strata and the surface. The evolution of fissures within the loose layer is a critical issue for surface ecological environment protection in coal mining areas. The study employed field measurements, mechanical experiments, numerical simulations, and theoretical analysis, using the ‘triaxial consolidation without drainage’ experiment to assess the physical and mechanical properties of various strata in the loose layer. Additionally, the PFC^2D numerical simulation software was employed to construct a numerical model that elucidates the damage mechanisms and reveals the evolution of loose layer fissures and the development of ground cracks. The research findings indicate that during shallow-buried high-intensity mining loose layer fissures undergo a dynamic evolution process characterized by “vertical extension-continuous penetration-lateral expansion”. As the working face advances, these fissures eventually propagate to the surface, forming ground cracks. The strong force chains within the overlying rock (or soil) layers develop in the form of an “inverted catenary arch”. As the arch foot and the middle of the arch overlap, fissures propagate along these strong force chains to the surface, resulting in ground cracks. The study elucidates the surface damage patterns in shallow-buried, high-intensity mining, offering theoretical insights for harmonizing coal mining safety with ecological conservation in fragile regions.

Regarding the failure of overburden strata and the development height of the “two zones” under repeated mining in close-distance coal seams, and to prevent various safety incidents such as roof water inrush and spontaneous combustion in goafs caused by water-conducting and air-leakage channels during face extraction, this study takes a mine in the Ordos region as the engineering background. By employing empirical formula prediction, drilling fluid loss measurement, borehole televising, numerical simulation, and intelligent prediction methods, the impact of repeated mining on the development patterns of the “two zones” in overburden strata and the evolution of separation spaces was analyzed. The research indicates that repeated mining in close-distance coal seams significantly increases the development height of the “two zones” in the overburden strata. The development height of the “two zones” far exceeds that resulting from the extraction of the upper coal seam, exhibiting a step-like increase with abrupt jumps between stages. The development characteristics of separations follow the sequence: “development of low-position separations → closure of separations → development of high-position separations → closure of high-position separations”. The error between the predicted value from the empirical formula and the field-measured value was considerable, whereas the relative errors compared with the numerical simulation and intelligent prediction values were only 1% and 3%, respectively, verifying the prediction accuracy. The findings can provide references for mining operations in similar working faces and analogous engineering contexts.