Mine Master drill rigs (also known as underground drill rigs, master rigs or face drilling rigs) are primarily utilized in underground mines (hard rock & soft materials) and tunnel construction.
[pdf] Compared with the drill and blast method, TBM tunnelling has significant advantages with high construction efficiency, low project cost, conducive to environmental protection, favorable stability contr.
[pdf] The name Bertha, after Seattle's first female mayor, , was chosen by a panel (that included the Governor and Transportation Secretary) from 150 submissions from kindergarten through 12th graders, who were asked to submit female names with Washington state heritage. The winning entry, which was submitted by two elementary schools in and , was selected in December 2012.
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