Theory and engineering practice of coal-water coordinated mining based on constraints of formation bearing capacity

Background The high-intensity mining of coal resources in the Yushen mining area has caused negative environmental effects and water disasters on coal seam roofs, seriously restricting the sustainable development of the area.

Methods and Results  Based on a summary of previous research results on the mitigation of the impacts of coal mining on groundwater resources and surface ecosystem, this study analyzed the contradiction between coal mining and the protection of the fragile ecosystem in the Yushen mining area in Shaanxi Province through theoretical analysis, field investigation, and data statistics. Then, it systematically illustrated the concept of the formation bearing capacity and its significance for the ecological environment. A formula for calculating the height of water flowing fractured zones that was applicable to ecologically fragile mining areas in western China was determined through fitting using mathematical statistics. Dominant factors controlling the formation structure damage were identified using the theory of simply supported beams and hydrogeological theories. Finally, based on the theory of coal-water coordinated development, this study devised the architecture of highly beneficial, coordinated coal mining technology based on the formation bearing capacity and developed the corresponding mining philosophy. This technology was applied to mining face 122107 in the Caojiatan Coal Mine. After mining along this mining face by gradually increasing the mining height based on blocks and segments, the overburden of the roof showed a stepped broken morphology generally. The water inflow along the mining face fluctuated around 170 m³/h throughout the mining process, not exceeding the drainage capacity of the mining face.

Conclusions The results indicate that it is necessary to take the formation bearing capacity as a core evaluation index for ecologically fragile mining areas. By controlling the dynamic balance between the mining technique and the formation bearing capacity, the coordination between resource development and ecological protection can be achieved. This mining approach can ensure highly beneficial coal resource mining while also addressing the contradiction between coal mining and the protection of the fragile ecosystem. The results of this study will provide a theoretical and technical reference for other arid and semi-arid mining areas in western China.