Investigation on the nanjing gypsum mine flooding

Abstract

Nanjing Gypsum Mine, or NGM, is encountering some engineering challenges in deep underground mining. The major challenges that affect the underground mine geomechanics and geoenvironment are attributed to groundwater, rock properties and geological structures, such as faults. A catastrophic mine flooding, triggered at NGM on 11 Sept. 2006, inundated the entire underground mine. The causes of this geological disaster are found multifold: hydrogeologically, the water-bearing karst rock overlain the orebody, the south of which was the direct water source of the catastrophic flooding; geomechanically, the low strength of the soft rock and the redistribution of mining induced stresses jeopardized the insitu balance and activated the discontinuities; and operationally, the inappropriate mining operation deteriorated the safety pillar and the ineffective seepage sealing method wasted the time for an effective measure to avoid the catastrophe. The mine flooding not only altered the underground hydrogeology, but also caused ground subsidence, damaged the surface structures and properties in the mine and its vicinity.© 2008 Science Press Beijing and Springer-Verlag GmbH Berlin Heidelberg Geotechnical Engineering for Disaster Mitigation and Rehabilitation.