Research on near/far-field flow characteristics of caved ore and rock based on rigid block model

The high mining costs of mines have led to the imbalance between the supply and demand of the total mineral resources in China and the dependence on imports to a large extent. Therefore, it is of great significance to expand the mining scale of mineral resources and reduce the mining costs to improve the self-sufficiency rate of mineral resources and strengthen social support and economic development in China. The caving mining method, especially the block caving method, has the following two main characteristics: one is that caved ores, surrounded by overlying rocks, are drawn from the drawpoint and the other one is that ground pressure is managed by filling goaf with overlying rocks. It is a low-cost and efficient large-scale underground mining method and has been widely used in metal mines around the world. To further reveal the far-field field migration and evolution mechanism of caved ore and rock in metal mine, through physical test, numerical simulation, and theoretical analysis, isolated-drawpoint draw models were constructed to study the flow characteristics of near/far-field flow characteristics of caved ore and rock. Based on the discrete element software PFC^3D and rigid block model, the numerical draw model was constructed for the first time. The reliability and superiority of the rigid block model in the study of flow characteristics of caved ore and rock were proved by comparative analysis between near-field physical draw test results and simulated results. Moreover, the variation law of the IMZ (Isolated Movement Zone), the stress evolution law and its mechanical mechanism in the particle flow system under far-field conditions were quantitatively studied. The key research results prove that: 1) The shapes of IMZ under near/far-field conditions conform to the upside-down drop shape theory. In the initial draw stage, the maximum width of IMZ increases rapidly with the increase of height in the form of power function; while in the following draw stage, the maximum width of IMZ increases almost linearly with the height increase. 2) There is an obvious stress arch effect during the flow of caved ore and rock. With the range expansion of the caved ore and rock, the vertical stress in a certain range outside the IMZ decreases obviously, while the horizontal stress gradually increases and surges before the arrival of IMZ. Furthermore, the horizontal and vertical stresses within the IMZ drop sharply to a lower level.