Abstract: Analysis of surface deformation caused by underground mining in metal mines can provide guidance for the mine safety production and prediction of surface deformation. Taking Chengchao iron mine, Hubei province, in China, for example. Through the investigation of underground mining situations and the analysis of monitoring data by GPS, leveling and three-dimensional laser scanning. The relationship between the mined-out area and the movement and break lines, the relationship between underground mining and settlement funnel expansion and the relationship between underground mining and displacement of measuring points are discussed. The results show that the expansion of movement and break lines in the western mining area mainly concentrated in the northeast, east and southeast direction from the year of 2006 to 2017 due to the -325, -342.5, -358, -375.5 m and -393 m level mined-out area expand continuously to the east, and a new funnel center developed in the east of the settlement funnel, and the funnel curve of the settlement funnel gradually shows two funnel centers. The displacement of measuring point just above the mined-out area is directly controlled by the underground mining. When the orebody below the measuring points is explored, the deformation of the measuring points will be accelerated obviously. However, the displacement of measuring points in the vicinity of the mined-out is affected by many factors. Based on the monitoring results, the caving process of overlying rock masses is analyzed. However, the mechanical models of rock masses around the mined-out area are established, and the deformation law of monitoring points is explained. The results can provide references for other similar metal mines.

Key words: metal mine, underground mining, surface deformation, deformation monitoring