JP2000178990A - Flexible structure type immersed tunnel and construction method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the efficiency of underwater tunnel construction work by connecting a plurality of unit box bodies in axial direction with connecting members coupled continuously, neighboring unit boxes are jointed through a water stop material thereby constructing sunk boxes, installing them on sea floor by connecting the sunk boxes together and reducing the section force acting to the sunk boxes. SOLUTION: A plurality of sunk boxes 1 are constructed by interposing a water expandable water stop material 4 having a high expandability to the jointing surfaces of a plurality of the unit box bodies 2, 2 and then jointing them together using a plurality of coupling cables 3, and a sunk box 1 is constructed. Unit box bodies 2a at the end portions of the sunk boxes 1, 1 butted together, bottom portions of both the notched parts are jointed with water stop plates 16, joint fittings 11 are jointed together, concrete 17 is placed in a recessed portion 9 consisting of the notched parts, a water stop grout material 14 is poured into the filled space 13 and is jointed to a rigid jointing state. Coupling between the sunk boxes 1 is in a state of rigid connection, but the unit box bodies 2 forming each sunk box 1 are coupled with a plurality of flexible coupling cables 3 and the water stop rubber 4, so that they are able to freely follow up differential settlement and crustal movement thereby decreasing the section force in the sunk box 1 in order to avoid the occurrence of a great section force.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexible submerged tunnel capable of freely following unequal subsidence of a submarine ground and crustal deformation at the time of a large earthquake, and a construction method thereof.

[0002]

2. Description of the Related Art Hitherto, a submerged box tunnel construction method has been generally known as a method of constructing a continuous tunnel below the water surface, such as a submarine tunnel.

In this buried box tunnel method, a tunnel box element (hereinafter referred to as a "buried box") pre-manufactured by a precast method in a production yard on land is towed to a planned site where foundation work is completed, and then to the planned site. It is a method of submerging a submerged box and joining adjacent submerged boxes together to construct a continuous tunnel on the water floor.

[0004] The submerged box is constructed by a RC structure, a PC structure or an SRC structure or the like, and is extremely long, about 100 m, and particularly has a very high rigidity. On the other hand, most of the submarine ground where the submerged box is submerged is a sedimentary layer, and is generally soft ground. , Measures against this were indispensable.

[0005] As a countermeasure against this, it has been common practice to bond the submerged boxes with a joint having a flexible structure, and FIG. 5 shows an example thereof. In the figure, ends of a connecting member 31 are respectively protruded from joints between adjacent sunk boxes 30, 30, and the ends of the connecting members 31 are connected to each other by a coupler 32.

[0006] At the joint between the adjacent submerged boxes 30, a waterproof material 33 and a gasket 34 are provided with a connecting member 31.
, Respectively, so that adjacent submerged boxes 30 and 30 are connected to each other.

[0007]

However, even if the buried boxes are joined to each other by the above-mentioned flexible joint method, the buried boxes are very long, about 100 m, and have very high rigidity. The relative displacement of the submerged box 30 at the joint is a considerable displacement.

For this reason, in the joint structure as described above, it is almost impossible to absorb the displacement of the joint due to crustal deformation at the time of a large earthquake, and it is unavoidable that a considerably large sectional force is generated in the submerged box. . For this reason, it is necessary to increase the strength (rigidity) of the buried box by arranging a considerable amount of steel material, and there are many problems in terms of workability and economy.

On the other hand, if a joint structure that can easily follow a considerable amount of displacement is adopted, the cost is greatly increased due to the complicated structure of the joint.
Furthermore, it is conceivable to construct the immersion box 30 shorter and increase the number of displaceable joints to reduce the cross-sectional force. However, as the number of joints increases, a great deal of labor is spent and the construction period is inevitably prolonged. . In addition, since the joining of submerged boxes is performed under water, there is also a safety issue.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and in particular, aims at reducing the sectional force acting on the submerged box and at the same time, makes it possible to construct a submerged tunnel very efficiently. The purpose is to provide a tunnel and its construction method.

[0011]

In order to solve the above-mentioned problems, a flexible buried tunnel according to the first aspect of the present invention has a plurality of unit boxes connected continuously in the axial direction. A plurality of submerged boxes are constructed by connecting the members with each other and interposing a waterproof material between the joint surfaces of the adjacent unit boxes, and the submerged boxes are installed and constructed on the water bottom while being joined to each other.

A flexible submerged tunnel according to claim 2 is
In claim 1, between the joint surfaces of the immersion box, a recess having a substantially groove-shaped cross section that opens inside the immersion box is provided continuously in the circumferential direction of the immersion box, and the recess is filled with concrete to join the immersion boxes. I do.

According to a third aspect of the present invention, there is provided a method of constructing a flexible-structured buried tunnel, in which a plurality of unit boxes are connected by a connecting member continuously installed in an axial direction thereof, and a plurality of unit boxes are connected to each other by connecting surfaces of adjacent unit boxes. A submerged box is constructed with a waterproof material interposed therebetween, and the submerged box is submerged in the water bottom and then joined to each other.

According to a fourth aspect of the present invention, there is provided a method for constructing a flexible-structured submerged tunnel, wherein the connecting member is tensioned and prestress is introduced into the submerged box until the submerged box is submerged and joined to the water floor. After the submerged box is submerged in the water bottom and joined, the connecting member is loosened as necessary to release the prestress, thereby providing a flexible structure.

[0015]

1 to 3 show an example of a submarine tunnel. In the figures, a plurality of submerged boxes 1 are installed at a relatively shallow position below the ground surface of the seabed while being joined to each other. A has been built. Further, both ends of the submarine tunnel A thus constructed are connected to the separately constructed tunnel B.
And is connected to the ground via this tunnel B.

The submerged box 1 has a predetermined length (50 to 100) by joining a plurality of unit boxes (box units) 2 with a plurality of connecting members (hereinafter referred to as "connecting cables") 3.
m).

2 (a) to 2 (d) show an example of a submerged box, in which a railway tunnel a is arranged at the center, and a roadway tunnel b is arranged on both sides thereof. The unit box 2 is constructed to a length of several meters (around 5m) by a RC structure, PC structure, SRC structure, or a steel-concrete composite structure in which concrete is cast in a steel plate formwork in the production yard on the ground. Have been.

A water-swelling water-stopping material (hereinafter referred to as "water-stopping rubber") 4 having an extremely large elasticity is interposed between the joining surfaces of the unit boxes 2 and 2. The waterproof rubber 4 is located between the joining surfaces of the unit boxes 2 on both sides of the connecting cable 3 and is continuously interposed in the circumferential direction of the unit box 2. The above is interposed again.

In the drawing, a single cable is interposed on each side of the connecting cable 3. Further, the water-stopping rubber 4 is fitted and fixed in concave grooves formed on both joining surfaces so as not to be easily peeled off.

A sheath 5 is buried continuously in the frame portion (floor plate, wall, and top plate) between the waterproof rubbers 4 and 4 in the axial direction, and the connection cables 3 pass through the sheath 5 respectively. Have been.

The connecting cable 3 is made of a flexible cable made of a PC steel wire or a PC steel stranded wire, and is so-called unbonded so that prestress can be easily introduced and pulled out later. It has a structure.

In particular, a notch 6 is formed at an end of the unit box 2a connected to the outermost side, and a gasket 7 and a stopper 8 are attached to the outside thereof. The notch 6 is formed by joining the immersion boxes 1 and 1 so that the joint section opens at the inside of the immersion box 1 and forms a recess 9 having a substantially groove-shaped cross section continuous in the circumferential direction of the immersion box 1. It is formed continuously in the circumferential direction of the unit box 2.

A fixing plate 10 and a joint fitting 11 made of a reinforcing steel or a steel material are attached to the end of the cutout 6, respectively, and the ends of the connection cables 3 are fixed to the fixing plate 10 by fixing nuts 12. I have.

The gaskets 7 are respectively provided on the joining surfaces of the unit boxes 2a so as to protrude continuously in the circumferential direction of the unit box 2a. Then, when the submerged boxes 1 and 1 are joined, the tip of the gasket 7 is in close contact with the other joint surface, whereby a filling space 13 is continuously formed in the circumferential direction of the unit box 2a between the joint surfaces. It has become so.

The stoppers 8 are also attached to both joint surfaces similarly to the gasket 7, and when the submerged boxes 1 and 1 are joined to each other, they abut against each other so that the gasket 7
Is not crushed, and serves as a spacer for securing the filling space 13.

Further, a filling pipe 15 for filling the waterproof space grout material 14 into the filling space 13 after the submerged boxes 1 are joined to each other is embedded in the unit box 2a. A plurality of filling pipes 15 are formed at predetermined intervals in the circumferential direction of the unit box 2a, and the filling-side open end thereof is formed to open inside the unit box 2a. Further, a large number of cotters (not shown) are provided on the joint surface of each unit box 2 to prevent shear displacement.

Thus, the immersion box 1 is constructed. Further, the buried boxes 1 and 1 thus constructed are joined with each other at the end of the unit box 2a on the sea floor, and then the bottoms of both notches are connected by the water stop plate 16, so that the two joint fittings 11 and Recesses 9 connecting the notches 11 and comprising the cutouts 6
Concrete 17 is poured into the interior, and the filling space 13 is filled with a water-stopping grout material 14 to be connected in a rigidly joined state.

At this time, the water stop plate 16 is installed continuously in the circumferential direction of the immersion box 1, and is fixed to the bottom of both cutouts 6 by anchor bolts 18. Also,
The joint fittings 11 are connected to each other via a connecting member 19 formed of a reinforcing bar, a plate, or the like. Further, a plurality of reinforcing reinforcing bars 20 are continuously arranged in the recess 9 in the circumferential direction of the immersion box 1. The connecting member 19 is fixed to both joint fittings 11 by welding or the like.

In such a configuration, even if the immersed boxes 1 are rigidly connected to each other, a plurality of connecting cables 3 having flexibility between the unit boxes 2 constituting each immersed box 1 and the waterproof rubber Since they are connected to each other by 4, it is possible to freely follow crustal deformation caused by uneven settlement or a large earthquake, and it is possible to minimize generation of a large sectional force in the submerged box 1.

Further, when the submerged box 1 is installed on the seabed, it can be installed without difficulty even if there is a little unevenness (undulation) in the seabed ground 6, and therefore, it is not necessary to make the foundation surface flat.

Next, a method of constructing a flexible-structured submerged tunnel according to the present invention will be described (see FIGS. 4A to 4D). In the production yard on the ground, the buried box 1 constructed as described above is towed to the planned point where the foundation work is completed. At this time, the connecting cable 3 is tensioned so as not to be damaged by the impact of waves during towing, and a prestress is introduced over the entire length of the submerged box 1 to unite the unit boxes 2 with each other.

If necessary, a plurality of reinforcing cables (not shown) are laid along the axial direction inside or outside the buried case 1, or both inside and outside, separately from the connecting cable 3. In addition, bulkheads 21 for adjusting the weight of the underwater are attached to both ends of the immersion box 1 (inside the box 2a). Next, ballast water is injected at the planning point, submerging box 1 is submerged on the seabed, and temporarily placed on the foundation. Next, the end of the immersion box 1 (the joint surface of the unit box 2a) is pressed against the end of the existing immersion box 1 (the joint surface of the existing unit box 2a) by jack pressure or the like. By doing so, a filling space 13 by the gasket 7 is formed between the joint surfaces of the submerged boxes 1.

At this time, a considerable amount of jack pressure acts on the gasket 7 attached to the joint surface of the unit box 2a, but the jack pressure is controlled so as not to excessively act on the gasket 7. Even if the pressure acts excessively, the stopper 8 is attached, so that the gasket 7 does not collapse due to excessive jack pressure. For this reason, it is not necessary to form the gasket 7 with expensive rubber or the like having particularly high strength and excellent deformation characteristics. Next, a water stop grout material 14 is filled in the filling space 13 formed between the joining surfaces of the unit boxes 2a, 2a.

The water-stop grouting material 14 is filled in the unit box 2a.
Through the filling pipe 15 in the water-stop grout material 1
When 4 is cured, the space between the bulkheads 21 and 21 is drained to finally hydraulically join the submerged boxes 1.

At this time, since the drainage between the bulkheads 21 and 21 is performed after the water-stop grout material 14 is sufficiently hardened,
All the strong water pressure between the joining surfaces is borne by the waterproof grout material 14 and is not shared by the gasket 7. Next, after the submerged boxes 1 are hydraulically bonded, the bulkhead 21 is removed, and the ballast water in the submerged box 1 is drained. Next, the prestress introduced over the entire length of the immersion box 1 is appropriately released by relaxing the tension of the connecting cable 3. Also, if a reinforcing cable is installed separately from the connecting cable 3 to integrate the unit boxes 2 during towing and submersion, the cable is also removed.

By doing so, each submerged box 1 has a flexible structure, so that even if there is unevenness (unevenness) on the base surface, each submerged box 1 can be easily placed on the base surface without generating a sectional force. Can be installed.

When the foundation surface is flat and there is no possibility that a sectional force will be generated in the immersion box 1, the immersion box 1 may be left in a rigid structure without releasing prestress. Next, a grout material is filled in the sheath 5 and the connecting cable 3 is integrated with the box 2 to thereby form the unit boxes 2 and 2.
It is a connecting material between them. Next, in the box 2a, the bottom of the concave portion 9, that is, the bottom of the cutout portion 6 is joined by bridging the water stop plate 16.

Further, the two joints 11 are connected to each other, and the reinforcing reinforcing bar 20 is arranged in the recess 9 formed by both the cutouts 6, and concrete 17 is cast. By doing this,
The submerged boxes 1 can be connected in a rigidly joined state.

As described above, even if the submerged boxes 1 are rigidly joined to each other, there is no particular problem since the unit boxes 2 have a flexible structure. Further, since the sunk boxes 1 can be rigidly joined to each other by the concrete 17, the manufacturing accuracy of the joint end face particularly required in the conventional hydraulic joining is not required.
In addition, since a particularly high construction accuracy is not required, the joining under the water surface can be performed very easily. In the same manner as described above, the buried tunnel 1 having the same flexible structure as the shield method can be constructed by laying and joining the buried box 1.

[0040]

The present invention has the above-described structure,
In particular, since each submerged box is connected to each other by flexible connecting members, a plurality of unit boxes can freely follow the crustal deformation accompanying uneven settlement and large earthquakes. The generation of a large sectional force can be reduced as much as possible.

Further, by connecting a plurality of unit boxes to form a submerged box as long as possible, submerging the submerged boxes in the water bottom and joining them together, it is possible to very efficiently construct a long water bottom tunnel.

Further, until the submerged box is submerged in the water bottom and joined, the connecting members are tensioned to introduce prestress into the submerged box, and the submerged box is made to have a rigid structure. Inadvertent sectional force does not act on the construction, and construction can be performed extremely efficiently and safely.

After submerging the submerged box on the water floor and joining, if necessary, loosen the connecting member and release the prestress to make the submerged box flexible, so that it can be installed on a slightly undulated ground without any particular trouble. it can.

[Brief description of the drawings]

1A and 1B show an example of a flexible buried tunnel, in which FIG. 1A is a cross-sectional view showing the entirety thereof, and FIG. 1B is a partial cross-sectional view thereof.

FIG. 2 shows an example of a submerged box, (a) is a plan view thereof,
(B) is a side view thereof, (c) is an axial sectional view thereof,
(D) is a sectional view perpendicular to the axis.

FIGS. 3A and 3B show a joint structure between buried boxes, wherein FIG. 3A is a sectional view showing a state before joining, and FIG. 3B is a sectional view showing a joined state.

FIGS. 4A to 4D are cross-sectional views showing a process of joining the buried boxes.

FIG. 5 is a cross-sectional view showing an example of a conventional joint structure between buried boxes.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Submerged box 2 Unit box (box unit) 2a Unit box (box unit) 3 Connecting cable (connecting member) 4 Waterproof rubber (waterproof material) 5 Sheath 6 Notch 7 Gasket 8 Stopper 9 Concave 10 Fixing Plate 11 Joint fitting 12 Fixing nut 13 Filling space 14 Waterproof grout material 15 Filling pipe 16 Waterproof plate 17 Concrete 18 Anchor bolt 19 Connecting member 20 Reinforcing reinforcing bar 21 Bulkhead

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Shigeki Honma 1-3-8 Moto-Akasaka, Minato-ku, Tokyo Kashima Construction Co., Ltd. Tokyo Branch F-term (reference) 2D055 AA09 EA01 EA05 GC03 GC09

Claims (4)

[Claims] 1. A buried box is constructed by connecting a plurality of unit boxes with connecting members installed continuously in the axial direction and interposing a water-stopping material between joining surfaces of adjacent unit boxes. Flexible submerged tunnels are constructed by installing these submerged boxes on the water floor while joining each other. 2. A recess having a substantially groove-shaped cross section which opens into the interior of the immersion box between the joint surfaces of the immersion box is continuously provided in the circumferential direction of the immersion box. 2. The flexible submerged tunnel according to claim 1, wherein the tunnel is joined. 3. A buried box is constructed by connecting a plurality of unit boxes with connecting members arranged continuously in the axial direction, and interposing a water-stopping material between respective joining surfaces of adjacent unit boxes. A method of constructing a flexible-structured submerged tunnel, characterized in that the submerged boxes are submerged on the water floor and joined to each other. 4. A rigid structure is created by tensioning the connecting member until the buried box is submerged on the water floor and introducing prestress into the buried box, and after connecting the buried box to the water floor and loosening the connecting member as necessary. 4. A construction method for a flexible-structured submerged tunnel according to claim 3, wherein the pre-stress is released to form a flexible structure.