| 摘要 |
PROBLEM TO BE SOLVED: To provide a method of quarrying from the underground cavity formed by the past mining in which pillars are left as supports. SOLUTION: The method comprises a step of forming a continuous underground wall above the underground cavity formed by the past mining in which pillars are left as supports, and a step of strip-mining a region enclosed by the continuous underground wall, and quarrying stones existing at least in one of a ceiling portion, column portions, and a floor portion of the underground cavity. COPYRIGHT: (C)2007,JPO&INPIT
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