JPH0419359B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <<Industrial Application Field>> The present invention relates to a method for starting a shield in an undersea tunnel construction method, and particularly to a method for improving the starting position of a shield.

<<Prior Art>> As is well known, as a type of method for constructing an undersea tunnel, a method for constructing a tunnel using a shield tunneling machine has been provided.

In this type of construction method, the shield tunneling machine is usually launched from a starting shaft that is excavated vertically into the ground, approximately parallel to the horizontal level of the tunnel to be constructed.

However, in this starting method, the starting shaft must be constructed to a considerably deep depth, resulting in a large economic disadvantage.

Therefore, a method has been considered in which the shield tunneling machine is launched from a starting shaft at an angle toward the seabed surface, and with this method, there is no need to construct the starting shaft to a very deep depth.

By the way, there are various conditions at the construction site of an undersea tunnel, and for example, it is assumed that a starting shaft must be constructed close to a place where the seabed suddenly becomes deeper from the coast.

If a shield tunneling machine is to be launched at an inclined angle under such location conditions, an embankment must be created between the launching shaft and the seabed surface. In this case, the method for creating the embankment is to set up a cofferdam along the area where the shield excavator is scheduled to pass, and then pour earth and sand into the cofferdam to construct an underwater embankment. Improvements were carried out by compacting the soil with water or by hardening it using a deep cement mixing method.

[Problems to be solved by the invention] However, in this method of starting a shield excavator using embankment, the embankment portion acts as a load on the soft seabed ground, which not only causes ground subsidence but also makes it difficult to improve the ground. The following problems arose in each case:

First of all, the coarse and fine particles of the soil thrown into the water separate, forming an uneven ground.
Even after compaction, there is no adhesion between particles, so there is a high risk of face collapse, and in severe cases, there is a problem of communication with the seawater above.

In addition, in the method of solidifying embankment earth and sand, uniform solidification cannot be achieved unless circular improvement bodies are closely wrapped in a plan view. Therefore, if an attempt was made to improve the underwater embankment using this method, there was a problem in that it would require a large amount of construction cost and construction time.

This invention was made in view of these conventional problems, and its purpose is to extend the actual starting position of the shield excavator to the seabed by using a submerged box. An object of the present invention is to provide a method for shield excavation in an undersea tunnel construction method, which enables the safe and reliable start of a shield excavator, and also shortens the construction period and reduces construction costs.

<<Means for Solving the Problems>> In order to achieve the above object, the present invention provides a shield starting method in an undersea tunnel construction method in which a tunnel is excavated on the seabed using a shield excavator, which comprises: A shaft for transporting equipment necessary for launch is formed on the coast close to the seabed ground, and a submerged box is sunk in an inclined state between the shaft and the seabed ground so that its tip penetrates the seabed ground. and driving a pile for supporting the immersed box between the immersed box and the seabed ground, incorporating the shield excavator into the tip of the immersed box, and starting the shield excavator from the immersed box. It is characterized by

<Operation> According to the shield launch method having the above configuration, a submerged box is installed in an inclined state between the launch shaft and the seabed surface, and the tip thereof penetrates into the seabed ground. Since the shield excavator is built-in, the shield excavator can be launched directly into the seabed without excavating the embankment. Furthermore, since the piles for supporting the submerged box are driven between the submerged box and the seabed ground, the submerged submerged box can be stably supported and the amount of embankment can be reduced.

<<Example>> Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIGS. 1 and 2 show an embodiment of the method for launching a shield in an undersea tunnel according to the present invention.

In the starting method shown in FIG. 1, first, as shown in FIG.

In this case, the depth of the shaft 14 may be relatively shallow without reaching the submarine ground 10.

When the shaft 14 is formed, a submerged box 16 is sunk between the shaft 14 and the seabed ground 10.

The immersed box 16 is sunk in an inclined state between the vertical shaft 14 and the submarine ground 10 along the planned line of the tunnel 18, and after being divided into appropriate lengths and fabricated on the ground, it is floated and submerged to the sinking site. will be sailed.

The divided immersed boxes 16 are sequentially connected from the shaft 14 side to the seabed ground 10 side, and the plurality of boxes on the tip side are buried while being positioned on the sloped part 20 that has been excavated and formed in the seabed ground 10 in advance. It is returned and penetrated into the seabed ground 10.

Further, the plurality of immersed boxes 16 on the side of the shaft 14 are supported by a plurality of piles 22, 22 driven into the seabed ground 10, and furthermore, the immersed boxes 16 and the piles 22, 22
An embankment 24 is provided around the outer periphery of the submerged box 16 to stably support it. In this case, the submerged box 16 is placed on the pile 2.
By supporting the submerged box 16 with the supports 2 and 22, the support strength of the immersed box 16 can be increased, so the amount of embankment 24 can be significantly reduced.

Furthermore, a shield excavator 26 for excavating a tunnel 18 is built in the most advanced part of the submerged box 16 that has penetrated into the seabed ground 10.

FIG. 2 shows an enlarged view of the leading edge of the immersed box 16.

In this embodiment, an enlarged portion 16a is formed at the leading end of the submerged burial box 16, and the leading end is closed with a removable temporary wall 28. Enlarged section 16a
A shield tunneling machine 26 is installed inside, and a reaction force receiving structure 30 is provided at the rear end.

And, in the front inclined part 20 of the temporary wall 28,
Launch protection section 32 with ground improvement as necessary
is formed.

When the immersed burial box 16 is placed in the state shown in FIG. The shield machine 26 is installed on the temporary wall 2.
8 is removed, the submerged box 16 is launched toward the submarine ground 10.

Here, a submerged box 16 with a built-in shield machine 26 is installed.
By adjusting its buoyancy, the shield aircraft 26
Even with the added weight of 1,000 yen, it can be floated and towed sufficiently to the sinking site.

Further, when launching the shield aircraft 26, it is possible to easily launch the shield aircraft 26 by improving the submarine ground 10 in front of the most advanced submerged box 16 and providing the launch protection section 32 as described above. However, immersed box 1
If the penetration length of the tip portion 6 is increased, it is not necessarily necessary to improve the submarine ground 10.

Now, according to the shield starting method in the undersea tunnel construction method performed as described above, the shield excavator 26 is sunk between the vertical shaft 14 and the undersea ground 10 with its tip part penetrating into the undersea ground 10. Since it is built into the leading edge of the immersed burial box 16, it can be launched directly toward the seabed ground 10 without excavating the embankment as in the conventional case.

This makes it possible to start the shield tunneling machine 26 safely and reliably.

In addition, the submerged box 16, which is provided for transporting equipment necessary for launching the shield excavator 26, is manufactured on the ground in advance and can be floated and towed to the submersion site, so the construction period for launching the shield excavator 26 is reduced. can be shortened.

Furthermore, since the plurality of piles 22, 22 for supporting the immersed box are driven between the immersed box 16 and the seabed ground, the submerged immersed box 16 can be stably supported.

<<Effects of the Invention>> As explained in detail in the embodiments above, according to the shield starting method for an undersea tunnel construction method according to the present invention, there is provided a shield starting method for an undersea tunnel construction method in which a tunnel is excavated on the seabed using a shield excavator. A shaft for transporting equipment necessary for starting the shield excavator is formed on the coast close to the seabed ground, and a submerged box is placed between the shaft and the seabed ground with its tip touching the seabed ground. The immersed box is sunk in an inclined state so as to penetrate, and a pile for supporting the immersed box is driven between the immersed box and the seabed ground,
By incorporating the shield excavator in the tip of the immersed box and launching the shield excavator from the immersed box, the shield excavator is launched directly into the seabed ground, allowing safe and reliable launch. becomes.

In addition, since the part corresponding to the conventional embankment section is formed with an immersed box, it is easy to construct it, and by setting the length of the immersed box appropriately, it is possible to launch the shield excavator from any position. , it is possible to simultaneously shorten the construction period and reduce construction costs.

Moreover, since the piles for supporting the immersed box are driven between the immersed box and the seabed ground, the immersed immersed box can be stably supported even if the amount of embankment is reduced.

[Brief explanation of drawings]

FIGS. 1a and 1b are cross-sectional views showing an embodiment of the method of the present invention in the order of steps, and FIG. 2 is an enlarged view of the main part of FIG. 1b. 10...Undersea ground, 12...Coast, 14...Shaft, 16...Sunken box, 18...Tunnel, 22...
...Pile, 26...Shield excavator.

Claims (1)

[Claims] 1. A shield launching method in an undersea tunnel construction method in which a tunnel is excavated on the seabed using a shield excavator, which includes forming a shaft on the coast close to the submarine ground for carrying in the equipment necessary for launching the shield excavator, and A submerged box is sunk between the vertical shaft and the seabed ground in an inclined state so that its tip penetrates the seabed ground, and a pile for supporting the submerged box is driven between the submerged box and the seabed ground. A method for starting a shield in an undersea tunnel construction method, characterized in that the shield excavator is built into the tip of the immersed box, and the shield excavator is launched from the immersed box.