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Underground
GOAL GETTER
Major player scores points
in the tunnel!
World
Cup football managers know that winning means having the right
blend of top-class players working together in harmony. On four
tunnelling projects in Japan, the right blend of top-class drilling
equipment is working in harmony - and winning praise for excellent
performances.
Four tunnelling projects in
Japan are achieving their underground goals, thanks to the problem-solving
attributes of equipment from Atlas Copco - a major player in the
Japanese rock drilling market.
The first project
is Daini Shibisan, a twin-track railway tunnel which will be part
of the high-speed railway system between Kagoshima and Kumamoto
on the large island of Kyushu, south of the Japanese mainland.
The 3,394 m-long
tunnel, one of 13 under construction, is being excavated by the
Kajima-Zenitaka-Shita joint venture - and a major problem was
the amount of groundwater present in the sandstone, shale and
clay environment. Drilling and reinforcement was complicated,
with holes collapsing as soon as they were drilled and major difficulties
in inserting cement to grout rock bolts.
| In
the Sobu road tunnel: The combination of a Rocket Boomer rig
and COP 1838 rock drill is being praised by the joint-venture
team for good performance and low running costs. |
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The solution was
Atlas Copco Swellex rock bolts, which need no cement.
Atlas Copco Boomer
drifting rigs install the bolts which, with the help of the ESP-A51
electrical Swellex pump, expand immediately to provide reinforcement
to the rock surrounding the drill holes.
In this type of
environment, the Swellex bolts perform much better than conventional
bolts. They are also cost-effective, as their use in the tunnel
has ended the expensive business of having to re-excavate rock
which has been deformed by insufficient reinforcement methods.
Efficient and reliable
Says Site Manager Tadashi
Tanaka: "The Swellex contribution to our operations is highly
valuable. The rock bolts proved to be an extremely efficient and
reliable method of dealing with the porous and highly-fractured
rock formation."
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Site
Manager Tadashi Tanaka. |
The Chuo Highway
connects Tokyo and Nagoya in central Japan and work is under way
to widen the road from two to three lanes. In this project, one
of the tunnels being excavated is called Shin-Iwatono, located
100 km north west of the capital.
Work on the 1,591
m-long tunnel, with its cross-section of 130 m2, is being carried
out by the Tobishima/Aisawa joint venture and the client is Japan's
public highway corporation.
Soft
rock start
Rock at the site
is andesite lava and tuff-breccia. Excavation began in soft tuff-breccia
with a road-header machine. After progressing 126 m, drill-and-blast
operations started with an Atlas Copco Rocket Boomer 352-2B -
the first in Japan, leased to the site by the Atlas Copco distributor
Drill Machine.
The drill rig
is equipped with two BUT 35 booms, COP 1838 rock drills, and BMH
6812 feeds. The advance per round is 1.2 m and penetration rates
are 2.5 m/min. in soft rock and 3.0 m/min. in hard rock (andesite).
Mountainous
terrain
Worksite Manager
Mr Reizo Yasunaga is satisfied with the drilling performance and
says that the Boomer 352-2B is faster than other drifting rigs
he has experienced.
The Rocket Boomer
rig-COP 1838 rock drill combination leased by Drill Machine is
achieving excellent results at two other Japanese sites.
| At
the Sobu site: Two rig operators involved in the micro-benching
excavation method in a Rocket Boomer H 195 underground drill
rig, equipped with COP 1838 rock drills. |
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The first is the
Sobu road tunnel, located in mountainous terrain on the road between
Kyoto and Yonago Tottori prefecture. COP 1838 rock drills are
fitted to a Rocket Boomer H 195 - again the first combination
of its kind in the country.
Total length of
the tunnel is 3,692 m, with a cross-section of between 90 and
100 m2, and excavation is by micro-benching, a common method in
Japan.
The rock is sandstone,
shale, tuff and porphyrite, with a compressive strength of 400-500
bar. Drilling 100 holes in 40-50 minutes with a penetration rate
of 3 m/min., the advance per day is 6 m.
Worksite Manager
Mr Shigeyuki Sanematsu of the Obayashi/Kawashima joint venture
team says they are very satisfied with the good performance and
low running costs of the Boomer-COP combination, which has a low
consumption of shank adapters and other accessories.
Comparing
rigs
The final project
is the excavation of a 1,526 m-long tailrace tunnel at the Kan-nagawa
hydropower site, where a two-boom Rocket Boomer 352-2B equipped
wth COP 1838 rock drills is operating along with another rig.
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An
Atlas Copco Boomer rig installing Swellex rock bolts. |
In rock conditions which are
basically mudstone, advance per blast in the 8.2 m diameter tunnel
is 2-2.5 m and a daily progress of 6-8 m totalled some 200 m by
the end of May.
Worksite Manager
Mr Yuzo Koga of Shimizu Corporation decided to lease the Rocket
Boomer so that its performance and running costs could be compared
with the other underground rig. These comparisons are still ongoing.
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