| 摘要 |
To prepare the panel, a network of tunnels is driven in a conventional manner into the rock below the level of a layer to be exploited. A barrier of a minimum thickness of forty to fifty metres is now left between these tunnels and the layers to be exploited. During the entire gasification, the individual connections between the tunnels and the layers located in the panel are a number of bores of small diameter which were drilled before the start of working and are lined with tubes cemented in place in the rock.
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