Abstract: In order to study and determine the reasonable thickness of river waterproof security pillar in Funing Lead-Zinc Mine, and combined with the actual engineering geological conditions near the No.0 exploration line of the Funing Lead-Zinc Mine, the height of water flowing fracture zone is obtained by using the theoretical calculation formula of water conducting fracture zone, and then the thickness of waterproof security pillar under NaLang River bed is determined to be 30 meters, so as to cut off the hydraulic connection between the river and the ore body. At the same time, in order to reduce the disturbance of underground mining to the surface river, the slicing and filling method is adopted to ensure the long-term stability of the upper NaLang River.

Key words: water-flowing fracture zone, empirical formula, stability, slicing and filling method, waterproof security pillar