Research on collaborative management technology of deep multi-coal seam mining and pre-reclamation in coal-grain composite area

• A new joint measurement scheme for delineating the boundaries of various damage area is provided. • A new cooperative management technique for mining pre-reclamation of deep multi-coal seam in high groundwater level coal-grain composite area. • Effectively resolve conflicts in mining and agriculture. • Important insights for realizing sustainable development goals in mining areas. Subterranean coal mining results in the occurrence of surface subsidence, soil degradation, and damage to agricultural lands, which is especially severe in regions with high groundwater levels. The collaborative reclamation scheme combining surface pre-reclamation and underground mining layout optimization can effectively control the problem of damage to farmlands. Hence, it is imperative to study the collaborative management technology. The research area for this study is Jiulishan Mine, located in coal-grain composite areas with a high groundwater table. Initially, a combined UAV and USV measuring system was utilized to acquire spatial data of the proposed reclamation area. Furthermore, we examined the evolution features of the subsidence ponding related to various mining methods using FLAC3D numerical modeling. Ultimately, the ArcGIS spatial analysis module was utilized to model and calculate the reclamation volume and rate for each plan. Our findings indicate that: (1) The extent of damage caused by shallow coal seam mining includes an area of 50.67 hm 2 for farmland damaged area (FDA), 31.49 hm 2 for seasonal subsidence ponding (SSP), and 23.51 hm 2 for perennial subsidence ponding (PSP). Additionally, the boundary subsidence values for each damaged area are 0.8 m, 1.6 m, and 2.8 m, respectively. (2) Through the optimization of deep coal seam mining designs, the spatial configuration of the subsidence basin is successfully altered, creating the necessary condition for the development of a dynamic pre-reclamation plan. (3) The reclamation rate of the optimized pre-reclamation (PR) scheme is significantly higher, ranging from 40 % to 44 %, compared to the reclamation rate of 24 % of the traditional reclamation (TR). The choice of a suitable land reclamation and ecological restoration strategy was determined by optimizing mining plans and considering the characteristics of the subsidence area. This offers empirical evidence and specialized assistance for the ecological rehabilitation of coal-grain composite areas with high groundwater levels.