Development of a combined mining technique to protect the underground workspace above confined aquifer from water inrush disaster

Abstract

AbstractOne task facing by the geotechnical engineers is to protect the workspace in an underground construction/excavation site from various forms of geological disasters, such as the water inrush, rock burst, and collapse of the surrounding rock/soil. In this paper, a combined controlling measure was proposed based on underground mining and water environment: the method of strip mining has been initially proposed as an effective measure against underground workspace floor failure when mining above confined aquifer in the Bucun coal mine, China, and however, its ability to avoid floor water inrush has yet to be demonstrated; in the next step, field trials using caving zone backfill technology to prevent underground workspace floor failure and excavate retained strip coal pillars were implemented based on the theoretical calculation and numerical simulation results. Engineering practice showed that the failure depth of the underlying strata of the workspace had no growth without the possibility of water inrush, and the safety of the underground space was achieved. Thus, this study represents a successful attempt to develop the combined strip mining and caving zone backfilling technique to ensure the safety of the underground workspace and control surface subsidence when excavating the retained strip coal pillars above confined aquifer. The proposed combined technique can also be used in other underground excavation activities with similar problems.