Underwater ground hole construction method and underwater piping structure

Abstract

To reduce construction time while retaining underwater ground.SOLUTION: An underwater ground hole construction method includes an underwater excavation process to excavate seabed ground 20G, a retaining frame installation process in which a ground retaining frame body 50, which is formed in a frame shape in a plan view and has an opening 52 in a side wall portion 50S, is sunk into the sea 20 and installed at the excavation bottom 20L of the seabed ground 20G, a surrounding re-burying process to rebury the area around the ground retaining frame body 50 with re-burying soil 60 while keeping the opening 52 closed, and an in-moving process to open the opening 52 and allow a tunneling machine 40, which excavates re-burying soil 60 toward the ground retaining frame body 50, to move from the opening 52 into the ground retaining frame body 50.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a method for constructing a water-bottom ground hole and a water-bottom piping structure. [Background technology]

[0002] 2. Description of the Related Art A tunnel penetration method is known for extending a tunnel into water such as the sea or a river (see, for example, Patent Document 1).

[0003] Also, a pipe-thrust construction method is known in which the ground is excavated horizontally from a starting shaft, and multiple pipes are inserted into the excavated hole one by one until the pipes reach the arrival shaft (see, for example, Patent Document 2).

[0004] Furthermore, a method for excavating a subway tunnel by using a shield machine is known (see, for example, Patent Document 3). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 8-193489 [Patent Document 2] Japanese Patent Application Publication No. 6-212891 [Patent Document 3] JP 2002-21466 A Summary of the Invention [Problem to be solved by the invention]

[0006] Incidentally, it is conceivable to form an access shaft for retrieving a tunneling machine by driving sheet piles into the bottom ground of the sea, river, etc. to act as a retaining wall and then excavating inside the sheet piles.

[0007] However, driving sheet piles into the waterbed is a time-consuming process, which could result in a prolonged construction period.

[0008] In consideration of the above, the present invention aims to shorten the construction period while retaining the bottom ground. [Means for solving the problem]

[0009] The construction method for a water-bottom ground hole as described in claim 1 comprises a water-bottom excavation step of excavating the water-bottom ground, a retaining frame installation step of submerging a retaining frame body that is formed in a frame shape in a plan view and has openings in its side walls underwater and installing it at the bottom of the excavation of the water-bottom ground, a surrounding backfilling step of backfilling the area around the retaining frame body with backfill soil while keeping the opening closed, and an entry step of opening the opening and entering a tunneling machine that excavates the backfill soil toward the retaining frame body through the opening into the inside of the retaining frame body.

[0010] According to the construction method for a water-bottom ground hole according to claim 1, first, in a water-bottom excavation step, the water-bottom ground is excavated. Next, in an earth retaining frame installation step, an earth retaining frame formed in a frame shape in a plan view and having an opening in a side wall is submerged in water and installed at the bottom of the excavated water-bottom ground.

[0011] Next, in the surrounding backfilling step, the surroundings of the earth retaining frame are backfilled with backfill soil while the opening is closed. Next, in the entry step, the opening is opened and a tunneling machine that excavates backfill soil toward the earth retaining frame is allowed to enter the inside of the earth retaining frame from the opening.

[0012] In this way, in the present invention, in the retaining frame installation process, the retaining frame is submerged in water and installed at the bottom of an excavation in the water bottom ground, which makes it possible to shorten the construction period compared to, for example, the case where sheet piles are driven into the water bottom ground to retain the earth.

[0013] Furthermore, in the present invention, vibrations, noise, and the like can be suppressed compared to, for example, the case where sheet piles are driven into the waterbed.

[0014] Furthermore, when using sheet piles to retain the waterbed, it is necessary to melt the sheet piles underwater, for example, to form an opening through which a tunneling machine can pass.

[0015] In contrast, in the present invention, openings are formed in advance in the side walls of the retaining frame, thereby making it possible to further shorten the construction period.

[0016] The construction method for a water-bed ground hole according to claim 2 is the construction method for a water-bed ground hole according to claim 1, in which the opening is opened by lifting up a closing plate that closes the opening in the entry step.

[0017] According to the construction method for a water-bottom ground hole according to claim 2, in the entry step, the closing plate that closes the opening of the earth retaining frame body can be pulled up, so that the opening can be easily opened. Therefore, the construction period can be further shortened.

[0018] The method for constructing a water-bed ground hole as described in claim 3 is the method for constructing a water-bed ground hole as described in claim 1 or claim 2, in which a thrust pipe is connected to the tunneling machine, and in a piping process after the entry process, the tunneling machine is removed from the thrust pipe inside the retaining frame body, and a water intake pipe or a drainage pipe is attached to the thrust pipe.

[0019] According to the construction method for a water-bottom ground hole according to claim 3, in the piping step after the entry step, inside the retaining frame, the tunneling machine is removed from the thrust pipe, and a water intake pipe or a drainage pipe is attached to the thrust pipe.

[0020] By thus securing construction space in the water bottom ground using the retaining frame, the tunneling machine can be easily retrieved and an intake pipe or drainage pipe can be easily attached to the thrust pipe.

[0021] The water-bottom piping structure of the water-bottom ground hole described in claim 4 comprises a retaining frame body formed in a frame shape in a plan view and having an opening in a side wall portion and buried in the water-bottom ground, a thrust pipe buried in the water-bottom ground and having a tip inserted inside the retaining frame body through the opening, and a water intake pipe or a drainage pipe installed inside the retaining frame body and connected to the tip of the thrust pipe.

[0022] According to the water bottom piping structure of claim 4, the earth retaining frame is formed in a frame shape in a plan view and has an opening in a side wall portion. This earth retaining frame is buried in the water bottom ground. A jacking pipe is buried in the water bottom ground. The tip of the jacking pipe is inserted into the inside of the earth retaining frame through the opening in the side wall portion of the earth retaining frame. The tip of the jacking pipe is connected to a water intake pipe or a discharge pipe installed inside the earth retaining frame.

[0023] In this way, in the present invention, by burying the retaining frame in the waterbed, the construction period can be shortened compared to when retaining the earth by driving sheet piles into the waterbed.

[0024] Furthermore, in the present invention, vibrations, noise, and the like can be suppressed compared to, for example, the case where sheet piles are driven into the waterbed.

[0025] Furthermore, when using sheet piles to retain the waterbed, it is necessary to melt the sheet piles underwater, for example, to form an opening through which a tunneling machine can pass.

[0026] In contrast, in the present invention, openings are formed in advance in the side walls of the retaining frame, thereby making it possible to further shorten the construction period. Effect of the Invention

[0027] As described above, according to the present invention, it is possible to shorten the construction period while retaining the water bottom ground. [Brief description of the drawings]

[0028] [Figure 1] FIG. 2 is an elevational sectional view showing a water conduit and a water bottom piping structure constructed by a water bottom ground hole construction method according to one embodiment. [Diagram 2] 1 is a vertical cross-sectional view showing a construction process of a construction method for a water-bottom ground hole according to one embodiment. FIG. [Diagram 3] 1 is a vertical cross-sectional view showing a construction process of a construction method for a water-bottom ground hole according to one embodiment. FIG. [Figure 4] FIG. 4 is a perspective view showing the retaining frame body shown in FIG. 3. [Diagram 5] 1 is a vertical cross-sectional view showing a construction process of a construction method for a water-bottom ground hole according to one embodiment. FIG. [Figure 6] 1 is a vertical cross-sectional view showing a construction process of a construction method for a water-bottom ground hole according to one embodiment. FIG. [Figure 7] 1 is a vertical cross-sectional view showing a construction process of a construction method for a water-bottom ground hole according to one embodiment. FIG. [Figure 8] 1 is a vertical cross-sectional view showing a construction process of a construction method for a water-bottom ground hole according to one embodiment. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] Hereinafter, one embodiment will be described with reference to the drawings.

[0030] 1 shows a water conduit 30 and a water bottom piping structure constructed by the method for constructing a water bottom ground hole according to the present embodiment. The water conduit 30 is, for example, a supply pipe for supplying seawater to a water tank 12 such as a water tank installed on the land 10 side, and connects the water tank 12 to the sea 20.

[0031] As an example, the water conveyance pipe 30 is constructed by a jacking method, and is composed of a number of jacking pipes 32. Specifically, the ground 10G of the land 10 is excavated laterally toward the sea 20 from the construction position of the water tank 12 as the starting shaft by a tunneling machine 40 (see FIG. 6), and the jacking pipes 32 are inserted into the excavated hole one by one. Then, at the arrival shaft H formed in the seabed ground 20G, the tunneling machine 40 (see FIG. 7) is withdrawn, and the water intake pipe 34 is attached to the tip 32T of the jacking pipe 32.

[0032] In this embodiment, a velocity cap (not shown) constituting a water intake is connected to the connection port 34U (see FIG. 8) of the water intake pipe 34. A cover body 36 such as a bottom trawl snag prevention plate is attached to this velocity cap. The outer periphery of the cover body 36 is fixed by a bag-type footing 38. The seabed ground 20G is an example of a water bottom ground.

[0033] The water bottom piping structure according to this embodiment is applied to the tip side (sea 20 side) of the water conveyance pipe 30. This water bottom piping structure includes a retaining wall frame 50, a jacking pipe 32 whose tip is inserted inside the retaining wall frame 50 through an opening 52 in the retaining wall frame 50, and a water intake pipe 34 connected to the tip of the jacking pipe 32.

[0034] Here, the construction method of the water bottom ground hole according to this embodiment is applied to the construction of the arrival shaft H, the water conveyance pipe 30 buried in the seabed ground 20G, and the water intake pipe 34. Hereinafter, the construction method of the water bottom ground hole according to this embodiment will be specifically described.

[0035] (Bottom excavation process) First, as shown in Fig. 2, in the bottom excavation process, the construction area of ​​the arrival shaft H and the surrounding seabed ground 20G are excavated by an on-board crane of a crane barge (not shown). At this time, for example, a sheet-like pollution prevention frame 22 is appropriately installed around the excavation area of ​​the seabed ground 20G. The pollution prevention frame 22 may be installed as necessary and may be omitted as appropriate.

[0036] (Underwater foundation construction process) Next, in the waterbed foundation construction process, the waterbed foundation 24 is constructed on the excavated bottom 20L of the seabed ground 20G. Specifically, a predetermined amount of stones is dumped into the sea 20 using a shipboard crane or the like, and the stones are laid down on the excavated bottom 20L of the seabed ground 20G to form the waterbed foundation (seabed foundation) 24. The waterbed foundation 24 may be provided as necessary, and may be omitted as appropriate.

[0037] (mounting frame installation process) Next, as shown in Fig. 3, in the earth retaining frame installation process, the earth retaining frame 50 is sunk into the sea 20 by the shipboard crane 14 and installed on the water bottom foundation 24. At this time, the earth retaining frame 50 is installed so that an opening 52, which will be described later, faces the land 10 (the connection side of the propulsion pipe 32). The inside of this earth retaining frame 50 becomes the arrival shaft H.

[0038] To further explain the mountain retaining frame body 50, as shown in Fig. 4, the mountain retaining frame body 50 is formed of steel plates, steel frames, etc. into a rectangular frame shape in plan view. In other words, the mountain retaining frame body 50 is formed into a hollow shape with a rectangular cross section that is open at the top and bottom. This mountain retaining frame body 50 has four side wall portions 50S. An opening 52 is formed in the side wall portion 50S of the mountain retaining frame body 50 on the land 10 (see Fig. 1) side.

[0039] The opening 52 is a circular through-hole that penetrates the side wall portion 50S of the earth retaining frame body 50 in the thickness direction. The tunneling machine 40, the lock door 42, and the thrust pipe 32, which will be described later, can pass through the opening 52. The opening 52 can be opened and closed by a closing plate 54.

[0040] The closure plate 54 is attached to the side wall 50S of the mountain retaining frame body 50 on the land 10 (see FIG. 1) side so as to be slidable in the vertical direction. The closure plate 54 is formed into a rectangular shape from a steel plate or the like, and is provided with a pair of hanging portions 54A at its upper end. This closure plate 54 is disposed along the outer surface of the side wall 50S of the mountain retaining frame body 50 while closing the opening 52. The side wall 50S of the mountain retaining frame body 50 is provided with a plurality of guide portions 56 that support the closure plate 54 so as to be openable and closable.

[0041] The guide portion 56 is formed in an L-shape. The guide portions 56 are arranged along both side ends and a lower end of the closure plate 54 in a state in which the opening 52 is closed, and support these side ends and the lower end. From this state, the opening 52 can be opened by pulling the closure plate 54 upward.

[0042] The closure plate 54 and the guide portion 56 may be provided on the inside of the retaining frame body 50, not limited to the outside of the retaining frame body 50. The shape and arrangement of the guide portion 56 can be changed as appropriate. Furthermore, the guide portion 56 is an example of a support portion that supports the closure plate 54 so that it can be opened and closed.

[0043] (Backfilling process) 5, in the surrounding backfilling process, with the opening 52 of the earth retaining frame body 50 being blocked by the blocking plate 54, the excavated area around the earth retaining frame body 50 is backfilled with backfill soil 60 all around using a shipboard crane or the like. This prevents the backfill soil 60 from flowing into the inside of the earth retaining frame body 50 from the opening 52 by the blocking plate 54. Note that, for example, a contamination prevention frame (not shown) is appropriately installed around the backfilled area.

[0044] In addition, a plurality of sandbags 62 are placed on the backfill soil 60 on the land 10 (see FIG. 1) side of the retaining frame 50, i.e., on the backfill soil 60 excavated by the tunneling machine 40, and the backfill soil 60 is compacted. In this state, the backfill soil 60 is excavated by the tunneling machine 40.

[0045] It should be noted that, instead of the sandbags 62, other weights such as concrete blocks may be placed on the backfill soil 60. The sandbags 62 are an example of weights. Furthermore, the sandbags 62 may be provided as necessary, and may be omitted as appropriate.

[0046] (Entry process) Next, as shown in Fig. 6, first, in advance preparation for the entry process, a platform 44 supporting the tunneling machine 40 is submerged in the sea 20 by a shipboard crane (not shown) or the like, and temporarily installed on the water bottom foundation 24 inside the earth retaining frame body 50. The platform 44 is then fixed to the earth retaining frame body 50 by a jack (not shown) or the like.

[0047] The entry process is carried out, for example, when the distance D from the tunneling machine 40 to the earth retaining frame body 50 reaches a predetermined value. In this entry process, first, the blocking plate 54 is pulled up by the onboard crane 14 to open the opening 52 in the side wall portion 50S of the earth retaining frame body 50. In this state, the tunneling machine 40 is operated to excavate backfill soil 60 toward the opening 52 of the earth retaining frame body 50, and the entire tunneling machine 40 is entered from the opening 52 into the inside of the earth retaining frame body 50.

[0048] Here, the tip 32T of the jacking pipe 32 is connected to the rear end of the tunneling machine 40 via a lock door 42. The lock door 42 and the tip 32T of the jacking pipe 32 are also advanced inside the earth retaining frame body 50 together with the tunneling machine 40. The tunneling machine 40 and the lock door 42, etc. that have advanced inside the earth retaining frame body 50 are supported by a stand 44 that is temporarily installed inside the earth retaining frame body 50.

[0049] (Piping process) Next, in the piping process, as shown in FIG. 7, the tunneling machine 40 and the lock door 42 are withdrawn from inside the arrival shaft H, and as shown in FIG. 8, the water intake pipe 34 is connected to the tip 32T of the propulsion pipe 32.

[0050] Specifically, first, as shown in FIG. 7, the connection between the tunneling machine 40 and the lock door 42 is released, and the tunneling machine 40 is pulled up and recovered using a shipboard crane or the like.

[0051] Next, a valve (not shown) of the lock door 42 is opened, and seawater is injected into the propulsion pipe 32. Next, the lock door 42 is disconnected from the propulsion pipe 32, and the lock door 42 is pulled up and recovered by an on-board crane or the like. Also, the platform 44 is pulled up and recovered by an on-board crane or the like.

[0052] Next, as shown in Fig. 8, the water intake pipe 34 is submerged in the sea 20 by a shipboard crane or the like, and installed on the water bottom foundation 24. As one example, the water intake pipe 34 is formed in a T-shape, and is installed on the water bottom foundation 24 with the connection port 34U facing up. In addition, the connection part of the water intake pipe 34 is connected to the tip 32T of the propulsion pipe 32 by a bolt or the like.

[0053] (Internal backfilling process) Next, as shown in Fig. 1, in the internal backfilling process, the inside of the retaining frame 50 is backfilled with backfill soil 64 using a shipboard crane or the like. At this time, a pollution prevention frame 22 is appropriately installed around the backfilled area. After that, a velocity cap (not shown) constituting a water intake is connected to the connection port 34U of the water intake pipe 34, and a cover body 36 such as a bottom trawl net snag prevention plate is installed on the velocity cap.

[0054] The configuration of the cover body 36 can be appropriately changed. Moreover, the cover body 36 may be provided as necessary, and can be omitted as appropriate.

[0055] (Action and Effects) Next, the operation and effects of this embodiment will be described.

[0056] As shown in FIG. 3, according to this embodiment, in the retaining frame installation process, as described above, the retaining frame 50, which is formed in a frame shape when viewed in a plan view and has an opening 52 in a side wall portion 50S, is sunk into the sea 20 and installed at the excavation bottom 20L of the seabed ground 20G.

[0057] Next, as shown in FIG. 5, in a surrounding backfilling process, the surroundings of the retaining frame body 50 are backfilled with backfill soil 60 while the opening 52 is closed by the closing plate 54.

[0058] Next, as shown in Figure 6, in the entry process, the blocking plate 54 is pulled up to open the opening 52, and the excavator 40, which excavates the backfill soil 60 toward the retaining frame body 50, is caused to enter the inside of the retaining frame body 50 through the opening 52.

[0059] Thus, in this embodiment, in the retaining frame installation process, the retaining frame 50 is submerged into the sea 20 and installed at the excavation bottom 20L of the seabed ground 20G, thereby making it possible to shorten the construction period compared to, for example, the case in which sheet piles are driven into the seabed ground 20G to perform retaining.

[0060] In addition, in this embodiment, vibrations, noise, and the like can be suppressed, for example, compared to the case where sheet piles are driven into the seabed ground 20G. Furthermore, by using the pollution prevention frame 22, pollution of the sea 20 can be suppressed.

[0061] Furthermore, when using sheet piles to retain the seabed ground 20G, it is necessary to form an opening 52 for passing the tunneling machine 40 by melting the sheet piles underwater, for example.

[0062] In contrast, in this embodiment, the openings 52 are formed in advance in the side wall portions 50S of the retaining frame body 50, so that the construction period can be further shortened.

[0063] Moreover, in the entry step, the opening 52 can be easily opened by lifting up the closing plate 54 that closes the opening 52 of the earth retaining frame body 50. Therefore, the construction period can be further shortened.

[0064] Furthermore, as shown in Figures 7 and 8, in the piping process, inside the retaining frame body 50, the tunneling machine 40 and the lock door 42 are removed from the thrust pipe 32, and the water intake pipe 34 is attached to the tip 32T of the thrust pipe 32.

[0065] In this way, by securing construction space on the seabed ground 20G using the retaining frame 50, the tunneling machine 40 can be easily retrieved and the water intake pipe 34 can be easily attached to the thrust pipe 32.

[0066] (Modification) Next, a modification of the above embodiment will be described.

[0067] In the above embodiment, the closure plate 54 is attached to the mountain retaining frame body 50 so as to be openable (slidable) in the vertical direction. However, the closure plate 54 may be attached to the mountain retaining frame body 50 so as to be openable (slidable) in the horizontal direction, for example. In this case, in the entry step, the closure plate 54 is slid laterally to open the opening 52 of the mountain retaining frame body 50.

[0068] Also, the closure plate 54 may be detachably attached to the side wall portion 50S of the mountain retaining frame body 50 by bolts or the like. In this case, in the entry step, the bolts or the like are removed from the closure plate 54 and the side wall portion 50S of the mountain retaining frame body 50, and the closure plate 54 is removed, thereby opening the opening 52 of the mountain retaining frame body 50.

[0069] In the above embodiment, the water conduit 30 is a supply pipe that supplies seawater to the water tank 12. However, the water conduit 30 is not limited to a supply pipe, and may be, for example, a discharge pipe that discharges water stored in the water tank 12 into the sea 20. In this case, for example, a drain pipe is connected to the tip 32T of the propulsion pipe 32 instead of the water intake pipe 34.

[0070] In the above embodiment, the water conduit 30 is connected to the sea 20. However, the water conduit 30 is not limited to the sea 20, and may be connected to, for example, a river or a lake. In this case, the retaining frame 50 is installed at the bottom of an excavation made by excavating the water bottom ground such as the bottom of a river or lake.

[0071] Although one embodiment of the present invention has been described above, the present invention is not limited to such an embodiment, and one embodiment and various modified examples may be used in appropriate combination, and it is of course possible to implement the present invention in various forms without departing from the gist of the present invention. [Explanation of symbols]

[0072] 20 Ocean (underwater) 20G Submarine ground (underwater ground) 20L Excavation Bottom 32 Propulsion tube 32T tip 34 Water intake pipe 40 excavator 50 Earth retaining frame 50S side wall 52 Aperture 54 Occlusion plate 60 Backfill soil

Claims

1. a bottom excavation step of excavating the bottom of the water; A retaining frame installation process in which a retaining frame formed in a frame shape in a plan view and having an opening in a side wall portion is submerged in water and installed at the bottom of an excavation on the water bottom ground; a surrounding backfilling process of backfilling the surroundings of the retaining frame body with backfill soil in a state where the opening is closed; an entry step of opening the opening and entering a tunneling machine that excavates the backfill soil toward the retaining frame body from the opening into the inside of the retaining frame body; A method for constructing a bottom ground hole comprising:

2. In the entering step, the opening is opened by lifting a closing plate that closes the opening. The method for constructing a water-bottom ground hole according to claim 1.

3. A thrust pipe is connected to the tunneling machine, In a piping step after the entry step, the tunneling machine is removed from the thrust pipe inside the retaining frame, and a water intake pipe or a drainage pipe is attached to the thrust pipe. The method for constructing a water-bottom ground hole according to claim 1 or 2.

4. A retaining frame body formed in a frame shape in a plan view, having an opening in a side wall portion, and buried in the water bottom ground; A thrust pipe is buried in the bottom ground and has a tip portion inserted into the inside of the earth retaining frame through the opening; A water intake pipe or a drainage pipe installed inside the retaining frame and connected to the tip of the jacking pipe; A bottom piping structure comprising:

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