摘要(英) |
This study aims
directly on the construction of a tunnel for Neng-Gao canal, and focus
on tunneling round to investigate the working efficiency of a small
irrigating tunnel. The influencing items of tunneling and improving ways
on working efficiency were proposed by both statistical analyses and
consultation. Therefore, the history of tunneling on Neng-Gao canal was
recorded by this research. It was found from the working site, most
of in-situ rock can be classified as Type-III and Type-IV, the
geological conditions of down stream is better than those of upper
stream. The geological condition more weak, the rounding time more long.
According to the statistical results, the drilling, the outing derbies,
the shotcrete, and the rock bolting dominate the constructing time. From
the tunneling test results, the optimum round length of 1.5m was found;
the blasting rock diameter of 20cm~30cm could lead a better blasting
effect. To cut down the drilling time, workman arranged the relaxing
holes did not accord the smooth blasting technology; this acting led
lots of continuous breaking time. To reduce the constructing time, rock
bolts were installed every 2-7 rounds. Although this way meets the
safety range with free support which is proposed by Bieniawski, it
contradicts the concept of NATM. A general squad was applied initially;
it was changed into several professional divisions due to the
engineering custom of counting price by working quantities. However, the
efficiency of professional divisions was as well as a general squad in
this study. It can be seen from the statistical analyses, the idleness
results from machines unavailable mainly, a damaged 601 drilling machine
is the main cause. |