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Tests and numerical
simulation of fire protection materials for immersed tunnels
Hiromitsu IIDA1, Toru KOBAYASHI1, Nobuaki KON2; Osamu
KIYOMIYA3
1.
Nippon Civic Consulting Engineers Co., Ltd. ; 2.
Takenaka Civil Engineering & Construction
Co. Ltd.;
3. Waseda University
Proceedings of Structural Engineering, Vol. 44A, pp.93-101. March 1998
Key words: immersed tunnel joint, vehicle fire, fire resistance, fireproof,
waterproofing gasket, FEM analysis
Background
Many past instances of vehicle fires in tunnels highlight
the importance of fireproofing as a structural design task.
However, Japan has no clear design
criteria for the fireproof structure of immersed tunnels, which are commonly
used for crossing rivers or stretches of coastal waters. A fire near the segment
joints will expose the rubber waterproofing gaskets and secondary rubber waterproofing
materials to direct flames, potentially leading to breaches of the seals and
flooding of the tunnel. Fireproof structural design is therefore essential
for immersed tunnels, particularly for joints, and it is desirable that the
design criteria be established at an early stage.
Research Summary
We applied various types of fireproofing to tunnel joints. Full scale model
fire tests of the joints (height 2.25 m, width 2.25 m, thickness 1.025 m, mass
about 10tf) were carried out to determine the extent to which fireproofing
increased the fire resistance of the immersed tunnel joint and the segment
itself. Numerical analysis of heat conduction was carried out using finite
element method (FEM), the analysis results were compared with the test results,
and appropriate fireproof structures for joints were confirmed. The FEM was
capable of reproducing the test temperatures reasonably well; however, the
point where the fireproof coating was damaged by fire could not be identified.
Nevertheless, a combination of FEM analysis and reference to actual test results
for many configurations of fireproof coating enables the appropriate structure
and material for fireproof joint-coating materials to be selected. |
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