| The penstock with two inclined shafts at the upper
part has two branch parts and four inclined shafts in the lower portion. It is
a waterway at about 1,265m in length. The upper inclined shaft is about 900m
long with an excavated diameter of 6.1m, 3.9 diameters within the iron pipe and
48 degrees of slopes whereas the lower inclined shaft is about 146m long, 3.9m excavated
diameters, 2.7 ― 1.9m diameters within the iron pipe and slopes at 48 degrees.
Since the penstock has a sudden slope at 48 degrees, observing safety
procedures during excavation is important. Thus, a tunnel boring machine (TBM)
was used for excavation at the upper inclined shaft while rise bowler was used
in the lower inclined shaft. |
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