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CAVE LOADS AND PARTICLE FLOW:
BAE is undertaking a major research project to better understand how the load on the extraction horizon of block caves is influenced by draw effects and cave fragmentation.
Cave loads aren’t very high compared to the intact strength of most rock material, but they are important for estimating damage and deformation around the cave, and they can cause additional damage at certain stages of caving in weak ground, or in ground which has been damaged. BAE has undertaken a number of numerical experiments using the 3D discrete element code EDEM to investigate these effects. The main focus has been on the influence of differential draw across the footprint and on the effects of different draw strategies.
It was found that loads on drawpoints vary generally as hang-ups and other minor problems occur, but the effects due to these minor draw problems are only local. The main concern appeared to arise when a larger section of the footprint became isolated within areas of much higher draw, for example as might occur if access was lost to adjacent crosscuts near the centre of the cave.
If you would like more information about this research, please contact David Beck at BAE.
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© BAE 2005 ACN 113083060 |
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Telephone: (+61) 8 9245 3287 Beck Arndt Engineering Pty Ltd 3 Nautilus Crescent NSW Australia |
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FIGURE: Load on particles in the drawpoints of a block cave. The draw from the central crosscuts was reduced for one simulated month, with the resulting effect on peak load. The local increase in load is significant for weak or damaged ground |
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FIGURE: Load on particles throughout the lower sections of a block cave |
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FIGURE: Detailed view of particle velocity. The high transit time of smaller particles is highly evident |
