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The Shield Tunneling Association
of Japan was established in 1999, and its membership consists
of 97 companies including leading general contractors,
TBM and lining segment manufacturers. Fourteen proven
and reliable shield tunneling methods have been registered
with the association to date, and the association is helping
to apply these shield tunneling methods to various projects
and promoting widespread use of those methods.
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In 1939, shield tunneling
was used successfully for the first time to construct
a circular railway tunnel. In the 1960s, shield tunneling
began to be used for various infrastructure projects
in urban areas, and the open shield method had its
heyday until the 1980s. The period from 1980 to 1990
saw a transition from open TBM to closed TBM such
as earth pressure balance shield machines developed
in Japan. At present, 98 percent of TBM machines used
in Japan are closed type. During the peak period in
the 1980s, as many as 300 contracts were awarded each
year for shield tunneling work, and marked progress
was made in infrastructure development. Today, the
number of shield tunneling contracts awarded each
year is around 90. However, with a variety of new
shield tunneling technologies developed such as the
13 shield tunneling methods.
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A variety of technologies
are being developed to promote the utilization of underground
space in built-up urban areas. The recent enactment of
a new law permitting the use of underground space at depths
of more than 40 m below ground surface has accelerated
the research and development of new shield tunneling technologies,
such as branching and enlargement.
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