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Home > R & D and Technologies > Paper > 1.2 DOT method
RECENT TECHNOLOGIES OF TBM(SHIELD) & PNEUMATIC CAISSON
1.2 DOT method
The DOT shield method was developed from 1987 with the concept of "Effective use of underground space". The outline of the method is as follows. (Ref. Figure-3)
(1)
Utilizing the characteristics of DK shield especially its spoke type of cutter.
(2)
Muddy soil pressure shield machine with Multi numbers of cutter arranged at equi-plane faces which make easier control of machine posture.
(3)
The method constructing a compound circular shape tunnel using DOT segments which consists of V-shape joint segments and panel segments.
(4)
Multiple circular sections can be arranged at vertical or horizontal orientation, and furthermore, both can be combined. (Ref. Figure-4)
(5)
In the case of a vertical orientation of tunnel, Right Of Way required can be smaller than what would have been required with 2 tunnels.
(6)
In the case of a horizontal orientation of tunnel, excavation can avoid other infrastructure or pipes.
(7)
The DOT tunneling method has been adopted for 18 projects so far. (including 4 projects oversea).
Figure-3 DOT machine
Figure-4 Vertical and Horizontal type
The 1st Project was New Traffic System in Hiroshima 1989 and The 1st Project in overseas was City Subway in Shanghai China in 2002.
(Ref. Figure-5)
Figure-5 DOT machine for Hiroshima and Shanghai Projects
One remarkable project utilizing DOT method is introduced as follows.
Project Name: High speed rail No.4 line Chayagasaka Park (Ref.Figure-6)
                        (DOT was applied for the other 6 sections)
Client: Nagoya city Traffic bureau
Diameter : Diameter 6.52m x W11.12m
Boring Distance : 1,007m
Over burden : 11 - 32m
Soil Type : Adhesive soil (N=10), Sandy soil (N=10 - 30)
Figure-6 DOT machine and Tunnel section with the special segments
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