June 4, 2002
Sumitomo Metal Industries, Ltd.
The "sandwich-type composite segments", which is a tunnel lining structure that combines steel and concrete, has been introduced into a double track rectangular shield tunneling construction of the Tozai Line of the Kyoto municipal subway.
Our company*s "sandwich-type composite segments", developed for tunnel linings by combining steel and concrete, has been introduced into the construction of the Tozai Line of the Kyoto municipal subway (Rokujizo North Construction Section) by the specified consortium composed of Kajima, Okumura, Daiho, Yoshimura and Okano. Recently, the assembly of the composite segments area has been completed.
The sandwich-type composite segments consists of steel shells filled with concrete, and in this project it has enabled rectangular shield tunneling to be performed for a double track subway shield in a subway crossover section for the first time in the world.
1. Features of the Sandwich-type Composite Segments
The exterior walls of the sandwich-type composite segments are formed with steel shells which are then filled with concrete. The segment is thus a combined structure of steel plates and concrete. The segment, by making good use of steel materials, is one-half to one-third thinner, and yet is at least as rigid and strong as existing RC structures.
Key features are:
(1) At a section such as a rectangular section shield where the bending moment (bending strength) increases, a tunnel can be constructed without increasing the lining thickness (thickness of segments).
(2) Since all the exterior walls are covered with steel plates, there is no concern about cracking or chipping.
(3) The combined structure of steel shells filled with concrete offers the benefits of tensile strength of steel and the compressive strength of concrete. This enables rational material selection for constant loads as well as seismic loads.
(4) For a rectangular section shield, a strong bending moment occurs not only at the main structure but also at the splice connecting segments. However, this combined structure enables the tensile strength affecting the splicing bolts to be conveyed to the main steel shells smoothly, so that high resistance at the splice can be realized.
(5) These advantages reduce overall cost, including the reduction of excavation in the case of a double track rectangular section in a subway crossover section.
2. Background of Introduction of the Sandwich-type Composite Segments
In the construction of the Tozai Line of the Kyoto municipal subway (Rokujizo North Construction Section), a rectangular section shield is currently under construction. The tunnel dimensions are a horizontal external diameter of 9,900mm and a vertical external diameter of 6,500mm. In this construction work, the opencut method is applied to the station building, and the shield method to the other construction areas.
Especially, the zone for about 60m toward the main track from the station building is called a crossover section, where rail tracks cross so that the center pillars cannot be installed at the rectangular section. This is why the rigid and strong sandwich-type composite segments has been adopted.
So far, the sections at a double track of a crossover section have been constructed with a round shield. However, the sandwich-type composite segments, which combines steel shells filled with concrete, has enabled a double track rectangular shield construction to be built for the first time in the world, greatly increasing the efficiency of construction works and reducing the cost.
This construction has been technically examined and discussed with the guidance of the Kyoto City Construction Technique Committee as well as the Rectangular Shield Study Working Group.
3. Project Outline
(1) Project Name: Kyoto Subway Tozai Line Rokujizo North Construction Section
(2) Construction Site: Between 23-1 Nara-machi, Rokujizo, Uji City and 27-4, Ishidamori higashi-machi, Fushimi-ku, Kyoto City
(3) Owner: Kyoto Municipal Transportation Bureau
(4) Constructor: Kajima-Okumura-Daiho-Yoshimura-Okano Construction JV
(5) Construction Period: From October 1, 1999 to October 31, 2003
(6) Shield Extension: 750m
(7) Crossover Section: 57m (composite segments)
(8) Connection Section: 5m (composite segments + center pillars)
4. Future Prospects
We will apply our new boltless joint "I-T joint" to the sandwich-type composite segments in the future construction of large-section shields.
Kyoto municipal subway Tozai Line construction work (Rokujizo North Construction Section)
Current status of the composite segments assembly
go back to list
|
|
