Abstract: Dahongshan Iron Mine in Yunnan is one of the large deep-laying underground metal mines in China. The deposit is situated at a joint of various types of complex regional structures, with a very complex geological structure and the potential conditions for rockburst hazard occurrence. In-situ stress measurement is carried out via six points located at 4 different sublevels by means of LUT Sweden in-situ stress measuring system, and its variation law and distribution characteristics are also studied. The results show that the maximum principle stress increases linearly with the depth increase, reaching about 47 MPa at maximum, with its azimuth angle ranging from N16°E to N 65°E, the average azimuth angle being around N 40.84°E, and the average inclination angle being 14.35°, only 2.89°at minimum, indicting that the horizontal tectonic stress is prominent here, which is very agreeable to the regularity of geological structure in this region.

Key words: Rock, 3D in-situ stress measurement, Dahongshan Iron Mine, In-situ stress state