Abstract:In order to effectively control the stability of a two-stage filling stope in an iron mine, a mechanism of coordinated support of the surrounding rock of the filling body is proposed. In the filling mining method, the stability of underground goaf mainly depends on the interaction mechanism of the combination of filling body and surrounding rock. In order to explore the cooperative support characteristics of surrounding rock and backfill under load, the numerical model is a more suitable tool to understand the damage scale, damage degree and type, damage location and damage occurrence time of the stope. By studying the mechanical characteristics and laws of the cooperative support between the filling body with different ash sand ratio and the surrounding rock and the roof during the filling of the goaf, the numerical simulation method is used to analyze the effect of the cooperative support between the filling body with different ash sand ratio and the surrounding rock in depth, and at the same time, the displacement changes, the maximum tensile stress changes and the plastic zone changes of the filling body, the top and bottom pillars and the surrounding rock after the completion of the mining and filling of the mine room are analyzed, Finally, the optimal ash sand ratio is selected, which provides a reliable basis for the safe production of the mine and the reduction of the filling cost.