Research on near/far-field flow characteristics of caved ore and rock based on rigid block model
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摘要: 為進一步揭示遠場條件下金屬礦山崩落礦巖運移演化機理，綜合利用物理試驗、數值模擬和理論分析等手段，構建單口放礦模型開展近?遠場崩落礦巖流動特性研究。首次基于離散元軟件PFC3D和剛性塊體模型構建放礦數值模型，并通過近場放礦物理試驗與模擬結果的對比分析，證明了剛性塊體模型在崩落礦巖流動特性研究中的可靠性與優越性。在此基礎上，對遠場條件下松動體形態變化規律、礦巖流動體系內的應力演化規律及其力學機理進行了量化研究。研究結果表明：1）近?遠場條件下的松動體形態變化均符合倒置水滴理論。在放礦初始階段，松動體最大寬度隨高度增大呈冪函數形式快速增加；隨后，松動體最大寬度隨高度增大而近似線性增加。2）崩落礦巖流動過程中存在明顯的應力拱效應。隨著礦巖散體松動范圍不斷擴大，松動體外圍一定范圍內的垂直應力均呈明顯下降趨勢，水平應力逐漸增大并在松動區域到達前出現激增現象；而松動體內的水平應力與垂直應力則急劇下降至較低水平。Abstract: 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 PFC3D 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.
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Key words:
- draw /
- near/far-field condition /
- caved ore and rock /
- flow characteristics /
- rigid block model
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圖 1 三維放礦物理與數值模型。（a）放礦物理試驗平臺；（b）放礦數值模型
Figure 1. 3D physical and numerical draw models: (a) physical draw test platform; (b) numerical draw model
圖 2 物理與數值試驗中的三維顆粒形狀。（a）物理試驗中存在的顆粒形狀；（b）過往數值模擬中選用的顆粒形狀；（c）本次數值模擬中選用的顆粒形狀
Figure 2. 3D particle shapes used in physical and numerical draw tests: (a) particle shapes in the physical test; (b) particle shapes used in previous numerical simulations; (c) particle shapes used in these numerical simulations
圖 3 物理與數值試驗中的顆粒級配曲線
Figure 3. Particle size distribution curves in physical and numerical draw tests
圖 4 篩分后所得不同粒徑的石灰石散體。（a）3～8 mm；（b）8～16 mm；（c）16～25 mm；（d）25～45 mm
Figure 4. Limestone particles with different sizes after sieving: (a) 3?8 mm; (b) 8?16 mm; (c) 16?25 mm; (d) 25?45 mm
圖 6 放礦物理與數值試驗中的放出體與松動體形態縱剖面圖。（a）物理試驗中的放出體；（b）數值模擬中高度50 m的放出體；（c）數值模擬中高度50 m的松動體
Figure 6. Longitudinal profiles of the IEZ’s and IMZ’s shapes in physical and numerical draw tests: (a) IEZ in the physical test; (b) IEZ with a height of 50 m in numerical simulation; (c) IMZ with a height of 50 m in numerical simulation
圖 7 放出體、松動體高度與最大半徑關系的近場放礦物理與數值試驗結果對比
Figure 7. Comparison of relationship between the height and maximal radius of IEZ/IMZ in near-field physical and numerical draw tests
圖 8 遠場放礦數值模型縱剖面圖和應力測量域布設
Figure 8. Longitudinal profile of the far-field numerical draw model and layout of stress measurement regions
圖 9 松動體高度與最大半徑關系的遠場放礦數值模擬數據和理論曲線對比
Figure 9. Comparison between the data of far-field numerical draw test and theoretic curve for the relationship between the height and maximal radius of IMZ
圖 10 第1、4、5、6、7號測量域內的垂直應力變化過程
Figure 10. Variations of vertical stresses within measurement regions Nos. 1, 4, 5, 6, and 7
圖 11 第1、4、7號測量域內的水平應力變化過程
Figure 11. Variations of horizontal stresses within measurement regions Nos. 4, 5, and 6
圖 12 第4、5、6號測量域內側壓系數倒數的變化過程
Figure 12. Variations of reciprocal of the lateral pressure within measurement regions Nos. 4, 5, and 6
圖 13 礦巖顆粒流動體系內應力拱和應力轉移示意圖
Figure 13. Schematic of stress arch and stress transfer within the particle flow system of caved ore and rock
表 1 墻體及剛性塊體細觀力學參數
Table 1. Meso-mechanical parameters of walls and rigid blocks
Walls Rigid blocks Normal stiffness/
(N·m?1)Shear stiffness/
(N·m?1)Friction
coefficientNormal stiffness/
(N·m?1)Shear stiffness/
(N·m?1)Density/
(kg·m?3)Friction
coefficient5×107 5×107 0.50 3×107 3×107 2620 0.50 
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