Xishan Mine Large Empty Area In The Lion Rock Copper Pillar Stability Study

The pillars' safe extraction in the huge open chamber is a serious problem to the metal mines of China. It is related with the sustainable development of mines directly. At present, it is being researched widely. With the practices of the No. 17 ore pillar' extraction under the huge open chamber with more than 2 million m3 in Xishan mining area of Tongling Shizishan Copper Mine, the paper analyzes and determines the wall rock's stability of the No. 17 ore pillar during the extraction by applying the ways of field monitoring, numerical simulation in computer, limiting equilibrium of rock mechanics and equivalent material simulation, etc. On the basis of it, the paper puts forward a reasonable implementing project for ore-pillar's extraction with safety, which will lead to good result in practice. The main researches have been done in the paper as follows:1. Through investigating the engineering geology and analyzing the rock's physical mechanical property, the paper put up qualitative evaluation to the rock's stability of the huge open chamber and No. 17 ore-pillar in Xishan mining area.2. The degree of reliability of the pillar and its top are analyzed in the paper by means of limit equilibrium. From it, the compression resistant safety factor of point pillar has been confirmed as 2.33 and 14.25 for the level ore-pillar.3. The condition of rock's stress-distortion before the pillar being excavated has been analyzed in the paper through numerical simulation of three-dimensional finite element so that the rule of geostatic change during ore-pillar being excavated can be recognized clearly.4. The rule of the geostatic change during the pillar' extraction under huge open chamber has been studied deeply through the test of equivalent material simulation and some strategies on the safety of pillar recovering has been advanced on the study.5. With the above researches work, the paper puts forward an implement project for the extraction of No! 17 pillar that is to do it step by step restrictedly and leaving permanent protective pillar.6. By applying the research findings into industry test of No. 17 pillar extraction,nour company has been extracted 344,000 tone ore safely with the economic benefit of 30,163,900 Yuan. The findings also have great value to extract the ore pillars under the similar huge open chamber safely.