论文部分内容阅读
鲁尔煤炭公司在瓦尔朱姆煤田用冻结法开凿一个叫维尔德的立井,其地质柱状如图1。
The Ruhr Coal Company used a freezing method to drill a Weild shaft in the Valjuj coal field. The geological column is shown in Figure 1.