| 摘要 |
The present invention is directed, inter alia, to devices and methods for excavating valuable materials, particularly soft ores such as oil sands, oil shales, and the like, that use one or more of a number of features, including backfillin g for ground support, a small trailing access tunnel, processing of the valuable material in the excavation with the tailings optionally being used as backfill and the valuable material being transported to the surface, a plurality of movable shields fo r ground support, and/or a movable tail shield to provide interim support to the backfill while additional liner sections are installed and/or formed.
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