Simulation analysis of factors and secure thickness of horizontal pillar for backfilling

The factor weights for horizontal pillar stability were obtained to analyze the stability of horizontal pillar of the Dongtong' V ore by applying AHP analysis method. The results show that the thickness of the horizontal pillar is the most important factor. The minimum safety thickness of the horizontal pillars is 5 m by using the formula of small deformation of thin plate theory. A numerical model is established to make a further analysis. The stress, vertical displacement and plastic zone of horizontal pillar thickness of 5 m to 9 m are analyzed. It is concluded that the horizontal pillar is likely to collapse when its thickness is less than 7 m.