ABSTRACT
ABSTRACT: In order to discover the effect of floor and rib failure on the whole entry stability in the three-soft coal seam, through site measurement and numerical simulation, the failure circle around the entry is obtained, and its mechanism is explored. Based on Protodyakonov’s arch theory, the limit equilibrium arch function of entry roof is set up by considering the effect of floor and rib failure. It is found that the height of roof equilibrium arch is proportional to the equivalent width of the entry, and is inversely proportional to the friction coefficient of the rib and the roof. When the rib fail, the equivalent width of entry increases, and the increment of roof equilibrium arch height is proportional to the depth of rib failure zone. When floor fails, it causes the equivalent height of entry to increase, and results in the equivalent width of entry increasing and the height of roof equilibrium arch increasing. The increment of roof equilibrium arch height is proportional to the floor failure depth. Thus, the theory of equilibrium circle of entry is established based, and it is pointed that strengthening the ribs and floor is important to improve the stability of the whole entry.
