ROCK MASS PLASTIC YIELD AND STABILITY ANALYSIS OF HEXAGONAL CENMENTED BACKFILL OF LONGSHOU MINE

Jinchuan nickel mine is Chinese most important nickel mineral resource base, which was characterized developed faults, structure plane and mine high grader. Longshou mine uses hexagonal approach cut and fill method. The collapse of the upper ore body and the filling body in the west mining area of Longshou Mine has a great influence on the below mining activities. This paper aims to analyze the mechanism of deformation and failure of mine body and filling. The numerical calculation model was used to analyze the changes of plastic yield zone and stress field during the process of filling and cementation. In the shallow area of mine body, the plastic yield area gradually increases with the progress of the stratified mining under the action of self-stress. Under the action of tectonic stress and self-stress, the plastic yield area of the deep mine body is larger than that of the deep ore body. With the excavation and filling, the vertical and horizontal structural stresses made the stress field redistributed, which was more favorable for the stability of rock mass. The upper plastic yield disappeared and the model entire yield area decreased. The tensile stress was mainly concentrated in the vicinity of the hexagonal section, especially the roof of rock. The horizontal and vertical tectonic stress changed the stress state of mine stope, and the tensile stress area around the hexagonal cross section decreased and the distribution was more uniform, which was favorable for the stability of the hexagonal section. But the compressive stress increased in the whole model area, and the plastic yield was easy to be far away from the hexagonal cross section. The long time cut and fill process will adversely affect the stability of the filling body and mine rock.