JP3796284B2 - Seismic isolation device for submerged box joint - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a seismic isolation coupling device for a buried box joint capable of buffering a seismic force acting on a jointed part of a buried box mainly deposited by a sinking method.
[0002]
[Prior art]
In recent years, for the construction of submarine tunnels on the riverbed and seabed, a submerged box, which is a tunnel element called a submerged construction method, is manufactured in a manufacturing yard, and both ends are blocked with temporary bulkheads and floated to the construction site. After being towed and set in a trench that has been dredged in advance, the submerged boxes are joined together using water pressure and backfilled to form a bottom tunnel.
[0003]
As shown in FIG. 6, the joint portion between the submerged boxes used conventionally has a structure in which a rubber gasket 2 is interposed between the submerged boxes 1 and 1 and is strained by the PC cables 3 and 3. One end of each PC cable is connected by a coupler 4. The other end of each PC cable is threaded, and this end penetrates the steel pipe 7 and the washer 10 integrated with the sinking box by the spiral reinforcing bar 5, and the PC is obtained by tightening the screw with the nut 9. The cable 3 is tensioned. This coupler 4 has a structure in which the end of the PC cable is fixed against the force in the direction in which each PC cable moves away from the joint portion of the sinking box, and the PC cable is not fixed to the force in the direction approaching the joint portion of the sinking box. It has become.
[0004]
When the force in the compression direction indicated by the arrow C in FIG. 6 acts on the joint portion, the joint portion having the above structure moves freely without the end portion on the coupler side being fixed by the coupler 4. 5, the compressive force acts on the rubber gasket 2 and the rubber gasket 2 is compressed so that the compressive force can be absorbed. However, the tensile force indicated by the arrow T in FIG. In this case, the end portion on the coupler side is fixed by the coupler 4, so that the tensile force can be absorbed only by the extension of the elastic region of the PC cable 3 as shown in FIG. 5. At this time, if the PC cable 3 is made longer, more tensile force can be absorbed, but the strain characteristics of the PC cable are less allowable than that of the rubber gasket, so the tensile force is absorbed as much as the compression force. I can't do it. Therefore, when the tensile force and the compressive force act alternately like the horizontal force at the time of an earthquake, the conventional connection structure of the joint portion has not been very effective.
[0005]
[Problems to be solved by the invention]
An object of the present invention is to provide a seismic isolation coupling device for a buried box joint that can sufficiently absorb not only a compressive force but also a tensile force with respect to a horizontal force acting during an earthquake.
[0006]
[Means for Solving the Problems]
In the present invention , a rubber gasket is provided on a joining end surface between sinking boxes to be joined and set, one end side of both PC cables for joining the sinking boxes is fixed to a coupler, and the other end side is substantially the same as a rubber gasket. It consists of an elastic body having characteristics and a seismic isolation connecting device for a buried box joint fixed through a stopper that prevents the elastic body from reaching the elastic limit.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Referring to FIG. 1, an embodiment of the seismic isolation coupling device for a submerged box joint according to the present invention will be described. In addition to the conventional example of FIG. A submerged box joint comprising a rubber gasket 2 provided on the outer periphery of the joining end surfaces of the submerged boxes 1 and a PC cable 3 for connecting the submerged boxes 1 and 1 to each other is provided and embedded in both submerged boxes. The PC cables 3 and 3 provided in the steel pipe 7 are connected at one end of the central portion with a coupler 4 and the other end of the PC cable 3 and 3 is passed through the steel pipe 7 and the washer 10 integrated with the sinking box by the spiral reinforcing bar 5. The screw at the end of the PC cable is fixed by tightening with a nut 9, and the configuration is almost the same as the conventional example of FIG. 6, but in the present invention, the PC cable 3 is buried as shown in FIGS. Nut with elastic body 11 at one end Are fixed by, forming the elastic body 11 of a material made of rubber or the like having substantially the same elastic properties as a rubber gasket 2.
[0008]
Furthermore, a stopper 12 for preventing the elastic body 11 from reaching the elastic limit and causing plastic breakage is interposed between the elastic body 11 and the nut 9 at the fixed end of the PC cable 3. And the magnitude | size of the steel pipe 7 and the stopper 12 of the part which positions the elastic body 11 is determined so that it may not restrain that an elastic body is compressed and the cross section becomes large.
[0009]
In the submerged box joint composed of the PC cable 3 described above, the submerged boxes 1 and 1 are held in tension at the joint between the submerged boxes 1 and 1 joined in the state shown in FIG. On the other hand, the rubber gasket 2 in FIG. 1 exhibits a buffering effect, while the elastic body 11 interposed at both ends of the PC cable 3 is compressed against the tensile force indicated by the arrow T in FIG. By demonstrating it, this submerged box joint can be made a seismic isolation structure.
[0010]
Further, in the conventional example of FIG. 6, since the buffering effect is expected by the extension of the PC cable 3 against the tensile force, the PC cable 3 needs to have a certain length. Since the elastic body 11 is interposed at both ends of the PC cable 3, the length of the PC cable 3 can be shortened compared to the conventional example of FIG.
4 is a strain characteristic diagram of a submerged box joint comprising the seismic isolation device of the present invention when the elastic body 11 of FIG. 1 is used, and FIG. 5 is a PC cable in the case of the conventional example of FIG. 3 is the same strain characteristic diagram when only 3 is used, but the rubber gasket 2 sufficiently absorbs the compressive force, and the breaking point is the same in FIG. 4 and FIG. In contrast, although the C cable 3 absorbs the tensile force to some extent, FIG. 4 shows that the allowable displacement on the tension side is increased by interposing the elastic body 11 in the present invention. It is clear that the invention has an effect that the elastic body 11 is interposed.
[0011]
【The invention's effect】
As described above, according to the seismic isolation coupling device of the submerged box joint of the present invention, since the elastic body is interposed at both ends of the PC cable on the side of the submerged box, it becomes possible to absorb the tensile force acting on the submerged box joint. Also, the length of the PC cable can be shortened compared to the conventional one, and furthermore, the elastic body is interposed at the fixed end of the PC cable, so that the elastic body is prevented from being elastically broken. be able to.
As a result, the durability of the joint portion is increased, the manufacturing cost is reduced accordingly, and the sinking work of the submerged box can be performed economically.
[Brief description of the drawings]
FIG. 1 is a side sectional view of an essential part in an embodiment of a seismic isolation coupling device for a sinking box joint of the present invention.
2 is a cross-sectional side view of a main part of a fixed end of the PC cable shown in FIG. 1;
3 is a cross-sectional side view of a main part of a fixed end of the PC cable of FIG. 2 when a tensile force is applied.
FIG. 4 is a strain characteristic diagram of the submerged box joint of the present invention.
FIG. 5 is a strain characteristic diagram of a conventional submerged box joint.
FIG. 6 is a sectional side view of a main part of a conventional submerged box joint.
[Explanation of symbols]
1 Sinking box 2 Rubber gasket 3 PC cable 11 Elastic body 12 Stopper

Claims (1)

A rubber gasket is provided on the joining end surfaces of the sinking boxes to be joined and set, one end of both PC cables that join the sinking boxes is fixed to the coupler, and the other end is elastic having the same elastic characteristics as the rubber gasket. Seismic isolation coupling device for submerged box joints fixed via a stopper that prevents the body and its elastic body from reaching the elastic limit .

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