Combined Drilling Methods to Install Grout Curtains in a Deep Underground Mine: A Case Study in Southwest China

Abstract

Curtain grouting can be used to reduce the volume of water inrush in a mine and protect regional groundwater resources. However, traditional vertical drilling was not feasible for the Maoping lead zinc deposit in Yunnan, China, which is located in a high mountainous region with steep gorges. A full analysis of the regional tectonic framework, and geological and hydrogeological conditions of the Maoping deposit was carried out, combining the use of different drilling methods (vertical drilling, inclined drilling with low curvature, and S-shaped directional drilling) to install grout curtains from mine roadways. The combination of drilling methods resolved the difficulties of underground drilling and grouting under high water pressure and the presence of fractures with a high dip angle. Water injection tests, drilling to reveal grouting quality, and electrical resistivity for closely spaced wells were used to to determine the continuity and permeability of the grout curtain. The grouting has been effective, ensuring the safety of the miners, sustainable exploitation of the deep mine resources, and allowing mining of previously non-extractable resources.