The advance detection and treatment of karst collapse columns - A case study of the Renlou Coal Mine in Anhui Province, China

摘要

Karst collapse columns are widely developed in Renlou Coalmine, Anhui Province, China. More than 10 collapse columns are detected so far in this mining area. In 1996, the first testing Panel 7222 encountered water inrush disaster because of the karst collapse column. The maximum volume of the water inrush quantity came up to 34570 m~3/h, which caused mine flooding and enormous economic loss. In this paper, a potential karst collapse column found during the excavation of No. II 5 tunnel in 2010 is selected as a case study to establish the advanced detection and treatment approaches for karst columns. The approaches proposed by this paper include three strategies: the first is the preliminary monitoring and anomaly analysis of water quantity, quality, temperature and pressure. Secondly, based on the monitoring work, geophysical prospecting is applied to determine the abnormal position of the collapse column. Thirdly, the accurate position and the range of column are confirmed by ground or underground drilling to the geophysical anomaly areas. Finally, the advanced detection approach in the way of grouting is applied, which blocks the hydraulic connection with the high pressure bottom Ordovician aquifer and plugs the collapse column. The approach eliminates the potential risk of water inrush during the roadway excavation.