Analyzing water recharge mechanisms and predicting water inflow in deep mining based on hydrogeological structures: a case study.

Abstract

Understanding water recharge mechanisms and accurately predicting water inflow are the fundamental objectives of mine hydrogeology investigation, particularly for ensuring deep mining safety. These investigation findings establish a scientific basis for planning drainage systems, optimizing mining layouts, and developing water hazard prevention and control measures. This paper takes the Maoping lead-zinc mine in Northeast Yunnan, China as a case study, which is a typical deep mine with significant water inflow challenges. Through systematic analysis of the mine's hydrogeological structural characteristics, this study identifies the principal water sources and pathways causing mine water inrush hazards. A three-dimensional numerical model was developed using FEFLOW software to predict mine water inflow under wet, normal, and dry years during multi-level mining operations in the Maoping lead-zinc mine. Furthermore, the evolution pattern of deep flow field under the influence of mining activities was analyzed. The investigation results indicate that the regional groundwater recharge to the Maoping lead-zinc mine originates primarily from the carbonate rock karst fissure aquifer of the Permian Qixia and Maokou formations in the northern mining area, with secondary contributions from the Carboniferous-Devonian karst aquifer in the southern mining area. Atmospheric precipitation in the Xianji syncline located east of the mining area recharges mine water through major water-conducting faults F46, F16, and F50. In addition, there is no centralized recharge pathways for mine water along the Luoze River. The numerical simulation results demonstrate that as the mining section deepens, the inflow of mine water gradually increases. The deep groundwater depression cone expands along both northeast and northwest directions. Guided by the characterization of mine hydrogeological structures, four proactive water hazard management strategies are established: (1) targeted treatment of risk sources, (2) coupled stress-seepage field control, (3) real-time monitoring and early warning, and (4) controlled dewatering and pressure relief. This study provides a typical example for the analysis of water recharge mechanisms and prediction of water inflow in deep mines with complex hydrogeological structural characteristics, and can serve as a reference for prevention, control, and management of mine water inrush hazards in deep mines.