Flow characteristics of caved ore and rock in the multiple draw-point condition

Based on the particle flow theory and PFC^3D code,a draw model was constructed to research the flow characteristics of caved ore and rock in the multiple draw-point condition and visualize the form-changing process of the isolated extraction zone(IEZ) and the ridge hangover body. Simultaneously,the suitability and reliability of this draw model were validated in the flow characteristics study of caved ore and rock by comparative analysis between simulated results and existing research conclusions. Due to interactions among multiple draw-points,the IEZ's form produces different degrees of variation in the multiple draw-point condition,including interlacement and deficiency,which result in that the IEZ's form is not a regular ellipsoid. The height changing trend of the IEZ in both the isolated draw-point condition and the multiple draw-point condition can be divided into two stages:in the first stage,the IEZ's height rapidly increases in an exponential form at the initiation of draw and its growth rate decreases with the increase of ore-drawn mass; in the second stage,the IEZ's height linearly increases with the increase of ore-drawn mass. The ore loss ratio decreases when the draw-point dimension and the height of the caved ore layer increase,but it increases with the increasing of draw-point spacing.When adjacent draw-points interact with each other,compared with a facade draw mode,the ridge hangover mass is less in a plane draw mode,and the contact surface of caved ore and rock horizontally drops.