Evaluation of Groundwater Inflow into an Iron Mine Surrounded by an Imperfect Grout Curtain

Grout curtains are often used to manage lateral water inflow. However, grout curtains constructed in extremely fractured rocks are not very effective, which poses a challenge for mine drainage and mining operations. So, it is crucial to consider the curtain’s effectiveness when evaluating water inflow. Large-scale pumping tests and groundwater numerical simulation were used in this study to evaluate the water inflow at an iron mine surrounded by an imperfect grout curtain. The effectiveness of the curtain was determined by comparing the hydraulic differences on both sides of the curtain and flow fields at pre- and post-grouting stages and three preferential seepage paths were identified. Given the mine’s complex boundary conditions, the telescopic mesh refinement modeling method was used; regional and local models were established using FEFLOW. The predicted inflow due to the gap in the curtain was 13,880 m3/day, accounting for 37.1% of the total 37,340 m3/day of water that still flowed into the mine. Two countermeasures, surface curtain remediation and underground grouting, were used to decrease water inflow and restore mine productivity.