Prediction of Ordovician limestone water level based on Logistic function and safety study of pressurized mining in lower group coal seams of Limin Coal Mine

The thick confined karst fissure aquifer of limestone beneath the Carboniferous-Permian coal seam floor is highly susceptible to floor water inrush under mining disturbances, posing a serious threat to mine safety. To address the problem of pressurized mining of the Ordovician limestone water in the floor of the Ⅱ0316 mining area of the Inner Mongolia Limin Coal Mine, based on an analysis of the hydrogeological characteristics of the Ordovician limestone aquifer in this mining area, the Logistic growth curve is used to fit the variation in the Ordovician water level elevation, revealing the rising pattern of the Ordovician water level and predicting the water level elevation at the time when mining commences. By combining data analysis with theoretical calculation, the predicted water level is incorporated into the calculation of the water inrush coefficient using the five-diagram and two-coefficient method, thereby achieving a forward-looking safety evaluation of the Ⅱ0316 mining area of the Limin Coal Mine. The results show that the Logistic growth curve provides a good fit, and it is predicted that the future Ordovician water level will tend toward a stable value of 980 m. The maximum water inrush coefficient in the study area is 0.043 MPa/m, which is lower than the critical value of 0.06 MPa/m. Combined with the three-level classification, the study area as a whole is classified as a safe zone, while the areas within 0–31 m of the SF2, SF3, SF4, and SF10 faults are identified as water inrush hazardous zones, which can be safely excavated after preventive measures are implemented. The research findings provide a reference basis for future Ordovician water level prediction and safe pressurized mining in the Limin Coal Mine, and offer a theoretical reference for the safety assessment of pressurized mining in Ordovician limestone water in mines with similar conditions in western China.