Study on the reasonable thickness of boundary roof pillars in the transition from open-pit to underground mining in a gold mine
A gold mine,from below 1 385 m elevation,will transition from open-pit to underground mining,intending to use the upward approach and filling mining method.In order to avoid mutual interference caused by simulta-neous open-pit and underground mining and achieve a smooth transition of mine production,it is necessary to study the reasonable thickness of boundary roof pillars.Based on relevant laboratory experiments,the reasonable range of bound-ary roof pillar thickness was calculated using the K.B.Lu Peinie equation,three-zone theory,and engineering analogy method.Flac3D software was used to numerically simulate different thicknesses of boundary roof pillars to determine the reasonable thickness for the transition from open-pit to underground mining in the mine.The results show that when underground mining is conducted in primary ore and oxide ore areas,boundary roof pillars of 20 m and 25 m respec-tively need to be reserved,at which point the impact of underground mining on open-pit slopes is minimized and the overall mining area tends to be stable,meeting the requirements for safe mine production.The research results can pro-vide a theoretical basis for mine design.
transition from open-pit to undergroundmining boundaryroof pillarsnumerical simulationFlac3D softwareroof pillar thickness
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