JP7628850B2 - Guide member for installation of immersed tunnel and construction method of immersed tunnel - Google Patents

Description

The present invention relates to an installation guide member for an immersed tunnel and a construction method for an immersed tunnel.

Underwater tunnels are generally constructed by submerging tunnel segments (hereinafter, tunnels constructed using this construction method are referred to as submerged tunnels). A specific construction method for submerged tunnels is towing a number of tunnel segments (submerged tunnels) that have been fabricated in advance in a yard on land or the like to the construction site, and submerging them one by one after laying and leveling gravel or the like at the bottom of a trench (ditch) that has been excavated in the bottom of the water. The submerged tunnels are then connected and joined to form a tunnel, the trench in which the tunnel is located is backfilled, and the water in the tunnel is drained to complete the construction (see, for example, Patent Document 1).
When each immersed tube is installed, high installation accuracy is required to prevent water from entering the tunnel from the connecting points. In general, when each immersed tube is installed, the installation accuracy is controlled by measuring the position using ultrasonic waves, by having divers descend to the site to directly measure and confirm the installation position, or by providing the tube with a mechanism for directly controlling the installation position (see, for example, Patent Document 2).

Japanese Patent Application Publication No. 5-34476 Patent No. 6342184

On the other hand, the above-mentioned immersed tunnel construction method has a problem in that it is not suitable for constructing tunnels with complex shapes, such as curved or multi-stage tunnels.
In addition, when controlling the accuracy of the construction of an immersed tunnel, divers may be required to go underwater to the site to control the accuracy, but the labor cost of divers is high, and the number of divers is on the decline, so there is the issue that it will become more difficult to secure divers in the future.In addition, there is the issue that the construction costs will be high because of the fact that people are directly sent to a special underwater construction site, and the efficiency in terms of construction time, cost, and safety will decrease depending on the various conditions of the construction site (water transparency, flow speed, water temperature, etc.).
In addition to the above, there are cases where specialized skills and techniques are required in the methods of managing the accuracy of sinking, and since there is a shortage of engineers, there is also the issue that it will become more difficult to secure personnel in the future.

The present invention was made in consideration of the above circumstances, and aims to provide an installation guide member for an immersed tunnel and a construction method for an immersed tunnel that can be used to immerse an immersed tunnel with high precision using a simple configuration and that can be applied to tunnels with complex shapes such as curves and multi-stage arrangements.

In order to achieve the above object, the installation guide member for an immersed tunnel according to the present invention is an installation guide member for an immersed tunnel formed by stacking hydraulic mixture discharged from a movable discharge part of an additive manufacturing device equipped with a mechanism for continuously discharging a soft hydraulic mixture from the discharge part, and is provided with a base plate having a sinking surface that faces the sinking lower surface of the immersed tunnel and stably positions the immersed tunnel, and a pair of guide walls formed on the sinking surface of the base plate at a distance that is approximately equal to the width length of the immersed tunnel.

The above configuration makes it possible to use additive manufacturing equipment to form installation guide members of the desired shape on-site, without the need for divers.

In addition, in the installation guide member according to the present invention, the pair of guide walls may be formed with tapered surfaces that are inclined from the tip of the guide wall toward the base end that contacts the sinking surface of the base plate in a direction in which the surfaces approach each other.

With the above configuration, the installation guide member has a bottom plate and a pair of guide walls with tapered surfaces, making it possible to easily guide the submerged box that constitutes the submerged tunnel to the specified installation position.

To achieve the above object, the construction method of the submerged tunnel according to the present invention uses the additive manufacturing device to form the installation guide member on a predetermined water bottom surface where the submerged tunnel is to be constructed, lowers a number of submerged boxes that constitute the submerged tunnel along the pair of guide walls, sequentially submerges the submerged boxes at predetermined submerged positions on the submerged surface, connects and joins adjacent submerged boxes together, and then drains the water from the submerged boxes to form the submerged tunnel.

With the above configuration, each immersed box can be sunk onto the installation surface along the tapered surfaces of a pair of guide walls provided on the installation guide member, and each immersed box can be sunk at the desired position with high precision.
In addition, the above-mentioned configuration allows the immersed tunnel to be installed with high precision, making it possible to install the immersed tunnel without the need for divers to control the installation precision, etc. This makes it possible to reduce the construction costs and shorten the construction period of the immersed tunnel.

In addition, in the construction method for an immersed tunnel according to the present invention, the specified water bottom surface on which the installation guide member is provided may be formed by leveling the water bottom surface so that the bottom slab can be stably positioned, and may be formed larger than the surface of the bottom slab facing the specified water bottom surface.

The above configuration makes it possible to reduce or eliminate the burden of the formation work, such as adjusting the amount of hydraulic mixture discharged depending on on-site conditions such as the inclination of the water bottom surface at the construction location of the immersed tunnel and the unevenness of the water bottom surface, when forming the installation guide member using an additive manufacturing device. This makes it possible to form the installation guide member with more accurate dimensions.

The present invention provides an installation guide member for an immersed tunnel and a construction method for an immersed tunnel that can be used to immerse an immersed tunnel with high precision using a simple configuration and can be applied to tunnels with complex shapes such as curves and multi-stage configurations.

FIG. 2 is a perspective view showing the construction status of an installation guide member in an example of a construction method for a submerged tunnel according to an embodiment of the present invention. 2 is a cross-sectional view taken along line AA' of FIG. 1, showing an example of an installation guide member according to an embodiment of the present invention. 2 is a view taken along the arrow B in FIG. 1 , showing an example of an installation guide member according to an embodiment of the present invention. 2 is a cross-sectional view taken along line AA' of FIG. 1, showing a modified example of an installation guide member according to an embodiment of the present invention. FIG. 2 is a perspective view showing the installation status of an immersed box in an example of a construction method for an immersed tunnel according to an embodiment of the present invention. 6 is a cross-sectional view taken along line CC' in FIG. 5, showing an immersed tunnel constructed by an example of an immersed tunnel construction method according to an embodiment of the present invention. FIG. 6 is a view taken along the arrow D in FIG. 5 , showing an example of an immersed tunnel constructed by a construction method for an immersed tunnel according to an embodiment of the present invention. FIG. 2 is a partial perspective view showing an immersed tunnel constructed by one of the modified examples of the immersed tunnel construction method according to an embodiment of the present invention. 1A and 1B are perspective views showing an example of a modified installation guide member and an example of a modified immersed can according to an embodiment of the present invention, respectively. In addition, FIG. 1A is a perspective view showing an example of a modified installation guide member, and FIG. 1B is a perspective view showing an example of a modified immersed can. A partial oblique view showing an immersed tunnel constructed using an example of a modified installation guide member and immersed box described above.

Hereinafter, an installation guide member for an immersed tunnel and a construction method for an immersed tunnel according to an embodiment of the present invention will be described with reference to Figs. 1 to 10 .
As shown in FIG. 1, the installation guide member 1 and the immersed tunnel 4 (see FIG. 5) in this embodiment are constructed in the sea W between the land tunnels T1 and T2 provided in the land ground L.G. of the lands L1 and L2, respectively. The installation guide member 1 is directly formed at the construction position by an additive manufacturing device 2 described later, and the immersed tunnel 4 is immersed and constructed on the installation guide member 1. The immersed tunnel 4 is connected to the boundaries E1 and E2 (hereinafter, the boundaries E1 and E2) between the land tunnels T1 and T2 and the sea W, integrated with the land tunnels T1 and T2, and used as an underwater tunnel. The boundaries E1 and E2 are isolated from the sea W to prevent seawater from entering the land tunnels T1 and T2. The boundaries E1 and E2 are provided in the land ground L.G.
In the following description, the width direction of the immersed tunnel 4 to be constructed is defined as the X direction, the traveling direction of the immersed tunnel 4 to be constructed is defined as the Y direction, and the depth direction of the sea W is defined as the Z direction.

First, when constructing the installation guide member 1 in this embodiment, the seabed ground UWG at the construction position of the installation guide member 1 is dredged by a dredger equipped with a bucket and capable of moving on the water. The dredging length in the X direction and the Y direction and the dredging depth in the Z direction in this embodiment are dredged lengths and dredging depths that allow the immersed tunnel 4 to be constructed to be connected to the boundaries E1 and E2 and to be stably positioned. As shown in FIG. 1, a leveling material such as crushed stone is laid on the dredged seabed ground surface BW by a ship equipped with a tremie pipe and capable of moving on the water to form a trench 3. The trench 3 also has a trench bottom surface 31 with a flat, leveled surface. In addition, the surface of the trench bottom 31 may be the ground surface that constitutes the seabed ground U.W.G., as long as the immersed tunnel 4 can be stably placed in the trench 3 and can be safely used after construction.

The trench 3 is formed in a groove shape having an inverted trapezoidal cross section with the short side at the bottom in the Y direction. The trench 3 is not limited to the configuration of this embodiment as long as the immersed tunnel 4 can be constructed in the trench 3 and can be safely used after construction. For example, the trench 3 may be formed in a groove shape having a rectangular cross section in the Y direction.
The surface of the trench 3 facing in the X direction is the ground surface that constitutes the seabed ground U.W.G. The surface of the trench 3 facing in the X direction is not limited to this embodiment as long as the immersed tunnel 4 can be stably arranged in the trench 3 and can be safely used after construction. For example, a leveling material such as crushed stone may be laid on the surface of the trench 3 facing in the X direction to form a side surface.

The configuration of an additive manufacturing apparatus 2 that forms an installation guide member 1 in this embodiment will be described with reference to FIG.
1, the additive manufacturing device 2 in this embodiment is installed on a loading vessel 28 capable of moving on water, and includes a mechanism for movably and continuously discharging the hydraulic mixture 21. The additive manufacturing device 2 forms a structure underwater by layering the discharged hydraulic mixture 21 at a desired position in the sea W.
The additive manufacturing device 2 also has a hopper 22, a pump 23, a controller 24, a hose 25, a nozzle 26 (discharge portion), and an electromagnetic valve 27 as mechanisms for movable and continuous discharge of the hydraulic mixture 21.

The hopper 22 is provided on the loading vessel 28 and is capable of temporarily storing a large amount of hydraulic mixture 21 for a period of time that maintains a specified quality. The external shape of the hopper 22 is a funnel shape with a wide opening on the side where the hydraulic mixture 21 is poured in. Note that the external shape of the hopper 22 is not limited to the external shape of this embodiment as long as it can temporarily store the hydraulic mixture 21 and supply it to the hose 25. For example, it may be a rectangular cylinder shape with an open top.

The pump 23 is connected downstream of the hopper 22. The pump 23 can adjust the amount of hydraulic mixture 21 supplied from the hopper 22 by controlling the operation of the pump 23 using a controller 24 provided in the pump 23.

The hose 25 has one end connected to the pump 23 and is arranged so as to be able to deliver the hydraulic mixture 21 supplied from the pump 23. The hose 25 also has a hollow cylindrical shape and is long enough to reach the bottom surface 31 of the trench where the installation guide member 1 is to be installed. The hose 25 is made of an elastic material. For example, rubber is used as the material. With the above configuration, the hose 25 can move within the range allowed by the length of the hose 25, and can be deformed within the range taking into account the elasticity of the hose 25.

The nozzle 26 is connected to the other end of the hose 25 as a discharge part for the hydraulic mixture 21. The nozzle 26 continuously discharges the hydraulic mixture 21 delivered through the hose 25, and the discharge amount of the hydraulic mixture 21 is controlled by the solenoid valve 27. In addition, the nozzle 26 is movable within a range considering the length of the connected hose 25, and can be freely discharged in any direction within a range considering the elasticity of the connected hose 25.

The additive manufacturing device 2 is not limited to the installation configuration of this embodiment as long as it is capable of continuously discharging the hydraulic mixture 21 onto the trench bottom surface 31 where the installation guide member 1 is to be installed underwater by the additive manufacturing device 2. For example, it may be installed on another floating structure such as a barge, or it may be installed on the coast on land if the construction site is close to land and the hose 25 can reach the trench bottom surface 31 where the installation guide member 1 is to be installed from land.

The additive manufacturing device 2 is not limited to this embodiment as long as it is provided with a mechanism for adjusting the amount of hydraulic mixture 21 supplied to the hose 25. For example, the amount of hydraulic mixture 21 supplied to the hose 25 may be adjusted by other mechanisms, such as by providing a delivery path with a gentle slope that connects the hopper 22 and the hose 25 and allows the hydraulic mixture 21 to be delivered, and providing a valve that can be opened or closed manually or automatically at the connection between the delivery path and the hose 25 as a mechanism replacing the pump 23 and the controller 24.

The additive manufacturing device 2 may also be equipped with a processing mechanism that can be remotely operated on land, taking into account the characteristics of the structure to be constructed. For example, this may include a trowel for smoothing the surface of the formed structure, or a mechanism for forming a new processed surface, such as a slope, on the surface of the formed structure.

The hydraulic mixture 21 has a softness that allows it to be easily molded in water when it is discharged, and also has a property of being difficult to diffuse in water. For example, underwater non-separating concrete or various cement-based materials that can be used in water (e.g., cement paste, mortar) are used.
In addition, there is no limitation on the manufacturing method of the hydraulic mixture 21, so long as the desired quality is ensured when the mixture is layered. For example, the mixture may be manufactured on land in advance, transported by another ship and anchored near the loading ship 28, and transferred to the hopper 22, or the loading ship 28 may be provided with a mechanism for manufacturing the hydraulic mixture 21, and the hydraulic mixture 21 may be manufactured on board the loading ship 28 and poured into the hopper 22.
In addition, as long as the desired installation guide member 1 can be applied, the method of layering the hydraulic mixture 21 is not limited. For example, the hydraulic mixture 21 may be extruded from the nozzle 26 and layered at a predetermined application position on the trench bottom surface 31, or the hydraulic mixture 21 may be sprayed and layered at a predetermined application position on the trench bottom surface 31.

In addition, if the hose 25 has a sufficient length to reach a predetermined construction position on the trench bottom surface 31 where the installation guide member 1 is constructed, and the hydraulic mixture 21 can be delivered without leaking from the hose 25 during delivery, a mechanism for adjusting the length of the hose 25 may be provided. For example, the hose 25 may be constructed by connecting multiple segments together without any gaps, and the length of the hose 25 may be adjusted depending on the number of segments connected together, and a mechanism may be provided that allows the length of the hose 25 to be adjusted depending on the water depth at the location where the hydraulic mixture 21 is discharged.

If the discharge position of the nozzle 26 is difficult to determine due to the hose 25, nozzle 26, and loading vessel 28 moving freely due to the tides and waves of seawater, a mechanism for controlling the position of the hose 25 may be provided. For example, the hose 25 may be provided with a robot arm that can be remotely operated on land and has a predetermined operability against swaying, such as not moving freely due to tides and waves, and not moving freely due to sea winds, or a gate-shaped frame may be provided on the loading vessel 28, and the hose 25 may be lowered to a position where the hydraulic mixture 21 is discharged.

In addition, if the hose 25, nozzle 26, or loading vessel 28 moves freely due to currents or waves, making it difficult to determine the discharge position of the nozzle 26, a mechanism for controlling the movement of at least one of the hose 25 and nozzle 26 may be provided. For example, an underwater drone or underwater camera that can be remotely operated from land may be provided to control the position where the hydraulic mixture 21 is discharged.

A method for constructing an installation guide member 1 using an additive manufacturing device 2 will be described with reference to FIGS. 1 to 3. FIG.
The installation guide member 1 is provided on a trench bottom surface 31 formed at the bottom of a trench 3 formed by dredging the seabed ground U.W.G. The installation guide member 1 is also provided between the boundaries E1 and E2.

1 to 3, hydraulic mixture 21 is continuously discharged from a nozzle 26 into a trench 3 formed by dredging the construction site of the installation guide member 1, and stacked from a predetermined position on the trench bottom surface 31 to a desired height to form a bottom slab 11. Similarly, hydraulic mixture 21 is stacked on the upper surface of the bottom slab 11 in the X direction at intervals that are approximately equal to the width of the immersed tunnel 4 in the X direction to form a pair of guide walls 12, 12 in the Y direction. The upper surface of the bottom slab 11 sandwiched between the pair of guide walls 12, 12 is formed as a sinking surface 13 for sinking the immersed box.
The trench bottom surface 31 is formed to be larger than the contact surface between the bottom plate 11 and the trench bottom surface 31 .

The two surfaces at both ends of the bottom slab 11 facing the Y direction are bonded to the boundaries E1 and E2. The bottom slab 11 has a sufficient thickness to function as a support for the immersed tunnel 4 when the immersed tunnel 4 is installed.
The outer shape of the bottom slab 11 is a flat plate shape elongated in the Y direction. The outer shape of the bottom slab 11 in this embodiment is not limited to the configuration of this embodiment as long as the immersed tunnel to be constructed can be stably arranged. For example, the ground surface of the trench bottom surface 31 and the ground surface of the trench bottom surface 31 of the bottom slab 11 may be approximately the same.

The distance in the X direction between the pair of guide walls 12, 12 and the width in the X direction of the sinking surface 13 approximately coincide with the width in the X direction of the immersed tunnel 4 to be constructed.
The two surfaces of both ends of the pair of guide walls 12, 12 facing the Y direction are respectively bonded to the boundaries E1, E2, similarly to the corresponding surfaces of the bottom plate 11. Similarly, both ends of the sinking surface 13 in the Y direction are also extended to the boundaries E1, E2.
The guide wall 12 has a tapered surface 17 in which an opposing surface 14 facing the opposing guide wall 12 is inclined from a sinking surface side tip 15 toward a sinking surface side base end 16 that contacts the sinking surface 13 of the base plate 11 in a direction approaching the opposing guide wall 12. The cross-sectional shape of the surface of the guide wall 12 facing in the Y direction has a trapezoidal cross-sectional shape with the side that contacts the upper surface of the base plate 11 being the long side.
Through the above steps, a desired installation guide member 1 as shown in FIGS. 2 and 3 is formed on the trench bottom surface 31.

In this embodiment, the pair of guide walls 12, 12 are provided with clearance upper surfaces 18, 18 at both ends of the bottom slab 11 in the X direction, which serve as clearance. The pair of guide walls 12, 12 may be formed in positions other than those in this embodiment, as long as the submerged tunnel 4 to be constructed on the sinking surface 13 can be stably positioned. For example, the clearance side surfaces 19, 19 of the pair of guide walls 12, 12 may be formed flush with the two surfaces at both ends of the bottom slab 11 facing in the X direction (the clearance upper surfaces 18, 18 may not be formed).

In addition, the pair of guide walls 12, 12 are not limited to the external shape of this embodiment as long as it is possible to stably position the immersed tunnel 4 to be constructed. For example, the tip of the guide wall 12 may be rounded, or as shown in Figure 4, the clearance side surfaces 19, 19 of the pair of guide walls 12, 12 may be formed perpendicular to the surface of the base slab 11 facing in the Z direction.

The guide wall 12 and the sinking surface 13 are not limited to the configuration of this embodiment, so long as they are capable of stably positioning the immersed tunnel 4 to be constructed and are configured so that they can be used safely after construction. For example, they may have a length in the Y direction that is equal to or greater than the length in the direction of travel of the immersed tunnel 4 to be constructed, or may be formed slightly shorter at the Y direction ends of each immersed box 41 to be sunk. Also, part of the sinking surface 13 in the Y direction may be omitted, and the base slab 11 and guide wall 12 may be formed with a predetermined gap in the Y direction.

In this embodiment, the pair of guide walls 12, 12 are formed after the bottom plate 11 is formed, but the order in which the bottom plate 11 and the pair of guide walls 12, 12 are formed is not limited to this embodiment as long as the desired installation guide member 1 can be formed. For example, the bottom plate 11 and the pair of guide walls 12, 12 may be formed simultaneously by moving the nozzle 26 back and forth in the X direction or Y direction to sequentially form the bottom plate 11 and the pair of guide walls 12, 12.

A method for constructing an immersed tunnel 4 using the installation guide member 1 will be described with reference to Figs.
5 to 7, after the construction of the installation guide member 1 is completed, the immersed boxes 41 constituting the immersed tunnel 4 are sequentially immersed using an immersed box immersion mechanism 5. After that, the immersed boxes 41, 41 adjacent to each other in the Y direction are connected and joined, and the water in the immersed boxes 41 is drained to form the immersed tunnel 4. At both ends in the Y direction on the immersed surface 13, the end immersed boxes 42, 42, which are a type of immersed box 41, are connected and joined to the boundary parts E1, E2.

The configuration of the submerged box installation mechanism 5 will be described.
As shown in Fig. 5, in this embodiment, a case where a conventional tower pontoon type mechanism is used for the immersed can installation mechanism 5 will be described. However, the mechanism is not limited to the one described in this embodiment as long as the immersed can 41 can be stably placed on the installation surface 13. For example, other well-known immersed can installation methods such as a placing barge method or a floating crane method may be used.
The submerged box installation mechanism 5 in this embodiment is composed of a pair of winch-equipped barges (submerged pontoons) 51, 51 that can move on the water and a winch control tower (winch tower) 52 installed on the upper surface (hereinafter, the upper surface) of the two surfaces of the submerged box 41 facing the Z direction. The winch-equipped barge 51 has a pair of winches 53, 53. The pair of winches 53, 53 has a suspension mechanism 54 that has the strength to suspend the submerged box 41 in water, and the submerged box 41 is submerged at a desired position on the submerged surface 13 by adjusting the length of the wire 55 that constitutes the suspension mechanism 54 (by gradually extending it downward in the Z direction). In addition, the winch control tower 52 manages the suspended submerged box 41 to always be stably sunk and sunk at the desired position.
In addition, the submerged box 41 has a number of hanging mechanisms 43 capable of hanging and detaching the lifting mechanism 54 of the winch 53, which are installed at predetermined positions on the peripheral part of the submerged upper surface of the submerged box 41 so that the submerged box 41 can be lowered.
The hanging mechanism 54 may be, for example, a mechanism in which a hook that can be detached is provided at the end of a wire 55 whose length can be adjusted by a winding device or the like.
In addition, the hanging mechanism 43 may be, for example, a ring-shaped suspension base that is fixed to a predetermined position on the submerged upper surface of the submerged box 41 and can hang and detach hooks that constitute the above-mentioned suspension mechanism 54.

The pair of winch-equipped barges 51, 51 is not limited to the configuration of this embodiment as long as it can stably position the submerged box 41 on the sinking surface 13. For example, the submerged box 41 may be suspended and towed underwater by a single winch-equipped barge 51, or it may be sunk.

The winch control tower 52 is not limited to the configuration of this embodiment as long as it can be stably lowered by a pair of winch-equipped barges 51, 51 and can be lowered at a desired position. For example, the winch control tower 52 may be provided on each of the winch-equipped barges 51, 51.

As shown in FIG. 5, the immersed canal 41 is formed in a box shape with an internal space in the Y direction when sunk, where an internal structure such as a road can be constructed. In addition, the immersed canal 41 is provided with bulkheads 44, 44 on two sides of both ends facing the Y direction when sunk, which isolate the inside of the immersed canal 41 from seawater, so that the immersed canal 41 can be towed in a floating state. The immersed canal 41 is formed from a material that takes into consideration the construction conditions. For example, underwater concrete that can be used underwater and has salt resistance can be exemplified. In addition, the immersed canal 41 is provided with a ballast tank, so that when the immersed canal 41 is sunk in a predetermined position, a weight such as seawater is poured into the ballast tank to sink the immersed canal 41.
In addition, the submerged cask 41, 41 adjacent in the Y direction drains the seawater from inside and is joined by the water pressure of the seawater. Between the submerged end submerged cask 42, 42 and the boundary portion E1, E2, the seawater from inside is also drained and joined by the water pressure of the seawater. The joint portion may be reinforced from inside the submerged cask 41 or from the land tunnel T1, T2. In addition, measures to protect the joint surface and prevent water ingress may be taken, such as providing a member such as a rubber gasket on the joint surface of the submerged cask 41 for cushioning and filling the gap during joining. In addition, the hydraulic mixture 21 may be filled using an additive manufacturing device 2 or a robot to fill the gap at the joint portion.

A construction method for an immersed tunnel 4 using the installation guide member 1 will be described.
First, as shown in Fig. 5, a pair of winches 53, 53 provided on each of a pair of winch-equipped barges 51, 51 are connected to the hanging mechanism 43 of the submerged box 41 to suspend the submerged box 41, and the submerged box 41 is towed to a desired installation position. After arriving at the installation position, the winch 53 is operated to gradually extend the wire 55 suspending the submerged box 41 downward in the Z direction, thereby lowering the submerged box 41, and each submerged box 41 is sequentially lowered in the Y direction to a desired installation position on the installation surface 13. When lowering the submerged box 41, the two surfaces at both ends of the submerged box 41 facing the X direction are lowered along the tapered surfaces 17, 17 of a pair of opposing guide walls 12, 12. After the submerged box 41 has been submerged on the desired installation surface 13, the lifting mechanism 54 that suspends the submerged box 41 is removed from the hanging mechanism 43 of the submerged box 41, and the submerged box 41 installation process is completed.

After submerged boxes 41, 41 adjacent in the Y direction are submerged at the desired positions on the submerged surface 13, the seawater inside is drained and they are joined by the water pressure of the seawater. After the submerged boxes 41, 41 adjacent in the Y direction are joined, the adjacent opposing bulkheads 44, 44 of each are removed, and they are connected through and joined. In addition, the end submerged boxes 42, 42 and the boundary parts E1, E2 of the end submerged boxes 42, 42 adjacent to each other are removed, and they are connected through and joined with the land tunnels T1, T2.

By carrying out the above process for all of the immersed tunnels 41 that make up the immersed tunnel 4, the immersed tunnel 4 as shown in Figures 6 and 7 is formed.
The order of sinking the immersed tunnels 41 is determined by the construction plan, the constraints of the construction conditions at the site, etc., but is not limited as long as the above is not determined and the desired immersed tunnel 4 can be constructed within a specified construction period. For example, the immersed tunnels 41 may be sequentially sunk from one end immersed tunnel 42 facing one of the boundary portions E1 and E2, and then joined and connected through, or the immersed tunnels 41 may be sequentially sunk from the other end immersed tunnel 42. Also, it is possible to start from sinking the immersed tunnels 41 other than the end immersed tunnel 42. Also, the sinking, joining, and connecting steps of the immersed tunnels 41 may be completed for all the immersed tunnels 41 before the next step is performed, or each step may be completed for each immersed tunnel 41, 41 adjacent to each other in the Y direction before sinking the immersed tunnels 41 adjacent to each other in the construction direction.

After the immersed tunnel 4 is formed, a leveling material such as crushed stone is laid on the immersed tunnel 4 and in the margins of the trench 3 by using a tremie pipe loaded on a ship capable of moving on water, for example, to backfill the immersed tunnel 4 and the trench 3. Note that, as shown in Figure 6, if the height of the immersed tunnel 4 is greater than the depth of the trench 3, material is also laid on the seabed ground surface B.W. around the trench 3 to form a mound-shaped backfill surface 6 and backfill the area.
The above steps complete the construction of the immersed tunnel 4. The immersed tunnel 4 is used as an underwater tunnel integrated with the land tunnels T1 and T2 via a configuration in which the end immersed boxes 42, 42 at both ends in the Y direction are connected to the boundary parts E1 and E2.

In this embodiment, the cross-sectional shape of the immersed box 41 in the X direction has a hollow rectangular shape that is elongated in the X direction. Note that, as long as the immersed box 41 can be sunk at a desired position on the sinking surface 13, the configuration is not limited to this embodiment.
For example, as shown in Fig. 8, on two surfaces at both ends of the immersed box 41 facing the X direction, the ends of each surface facing the base ends 16, 16 on the sinking surface side when the immersed box 41 is sunk may be formed with immersed box tapered surfaces 45, 45 that are close to and face the tapered surfaces 17, 17 and that substantially match the shape of the tapered surfaces 17, 17. As shown in Fig. 8, if the tapered surfaces 17, 17 and the immersed box tapered surfaces 45, 45 are formed as curved surfaces that substantially match in shape, the pair of guide walls 12, 12 and the immersed box 41 come into contact with each other at the curved surfaces, and therefore the stress at the corners acting from the immersed box 41 to the installation guide member 1 when the immersed box 41 is sunk on the sinking surface 13 is alleviated. Therefore, when the immersed box 41 is sunk, the installation guide member 1 and the corners of the immersed box 41 are less likely to chip, making it possible to prevent damage during construction.

In addition, when sinking the submerged box 41, the installation guide member 1 and the submerged box 41 may be fitted together to enable the box to be sinked at a predetermined position with high accuracy.
For example, as shown in FIG. 9A, the pair of guide walls 12, 12 are formed with tapered surface side recesses 121, 121 from the tapered surface 17, 17 side at the Y-direction intermediate portion. The tapered surface side recesses 121, 121 are formed with an inverted trapezoidal cross-sectional shape in the X-direction, with the installation positions in the Y-direction being approximately the same. Also, as shown in FIG. 9B, the immersed box 41 is formed with immersed box tapered surfaces 45, 45 at the lower end of both ends facing the X-direction. The immersed box 41 is formed with protrusions 46, 46 formed so as to be able to fit into the tapered surface side recesses 121, 121 when immersed at a predetermined position of the installation guide member 1, at the Y-direction intermediate portion of both ends in the X-direction. The immersed box tapered surfaces 45, 45 may be formed from lower extensions 47, 47 extending in the X-direction, respectively, to maintain the strength of the lower end of the immersed box 41.

With the above configuration, as shown in FIG. 10, when the submerged box 41 is sunk, the installation guide member 1 and the submerged box 41 are engaged to form the butt joints 7, 7, making it possible to reliably sunk the submerged box 41 in a predetermined position. Note that, as long as the submerged box 41 can be sunk in a predetermined position by engaging the installation guide member 1 and the submerged box 41, the engagement points are not limited to the configuration of the above example. For example, the butt joints 7, 7 may be provided at diagonal positions in the Y direction, or the installation guide member 1 and the submerged box 41 may be engaged with one butt joint 7.

In addition, as long as the desired quality is ensured, the immersed canister 41 may be prefabricated at a land facility such as a dock and towed to the construction site and then submerged, or a dredger or loading vessel 28 may be provided with a mechanism for manufacturing the immersed canister 41, which may be manufactured directly at the construction site and then submerged.

The immersed tunnel 41 in this embodiment is manufactured taking into consideration its size, weight, etc., so that it can be safely towed and sunk by a pair of barges 51, 51 with winches. In addition, if the shape is simple like the immersed tunnel 4 in this embodiment, the immersed tunnel 41 that constitutes the immersed tunnel 4 is equally divided and manufactured, improving workability. The immersed tunnel 41 may also be manufactured taking into consideration various conditions such as manufacturing efficiency, for example by dividing it into sections using boundaries where the shape of the immersed tunnel 4 to be constructed changes, such as inflection points, as a guide.

In addition, when the shape of the immersed tunnel 4 to be constructed is complex, such as a curve or a multi-stage arrangement, the base plate 11 and the pair of guide walls 12, 12 that constitute the installation guide member 1 are formed according to various conditions such as the shape of the immersed tunnel 4 to be constructed. For example, the immersed tunnel 4 to be constructed may have a shape that curves midway, or two immersed tunnels 4, 4 may cross over each other underwater. In addition, if the pair of guide walls 12, 12 can stably position the immersed box 41 and can join adjacent immersed boxes 41, 41, they may also be provided in the X direction by forming tapered surfaces 17, 17 facing each other in the Y direction to assist the immersion of the immersed box 41 from all four sides of the immersion surface 13.

Furthermore, the backfilling of the immersed tunnel 4 and the trench 3 is not limited to this embodiment as long as the immersed tunnel 4 can maintain the desired function. For example, the immersed tunnel 4 may be used with a part of the upper surface of the immersed tunnel 4 in the Z direction exposed.

In addition, if the underwater environment at the construction location of the submerged tunnel 4 is significantly small in external forces such as tides and waves and has no effect on the submerged tunnel 4, the construction method is not limited to the one described in this embodiment. For example, the submerged tunnel 4 may be constructed on a flat, leveled seabed ground surface B.W., and material may be laid around the periphery of the submerged tunnel 4 to form a mound-shaped backfill surface 6, which covers the submerged tunnel 4.

Next, we will explain the function and effect of the installation guide member 1 for the submerged tunnel 4 and the construction method for the submerged tunnel 4 according to the present embodiment described above.

In this embodiment, the hydraulic mixture 21 is discharged from the nozzle 26 provided on the additive manufacturing device 2 to a predetermined position on the trench bottom surface 31, and the nozzle 26 is moved appropriately while stacking the mixture. By using the additive manufacturing device 2, it is possible to form the installation guide member 1 of a desired shape on site without deploying divers. Furthermore, even if the sea surface is rough with strong winds, the seabed is often calm, so the construction of forming the installation guide member 1 can proceed as planned. Furthermore, even if the shape of the immersed tunnel 4 is complicated, such as having branches and changing heights, the installation guide member 1 can be constructed with high precision.
In addition, since the installation guide member 1 has a configuration including a bottom slab 11, a pair of guide walls 12, 12 each having a tapered surface 17, 17 inclined toward the opposing guide wall 12, and a sinking surface 13 sandwiched between the pair of guide walls 12, 12, it becomes possible to easily guide the multiple submerged boxes 41 that make up the submerged tunnel 4 to a predetermined sinking position.

In addition, in this embodiment, by a process of sinking the submerged box 41 along the tapered surfaces 17, 17 formed on a pair of guide walls 12, 12, it is possible to sink each submerged box 41 at a predetermined position on the sinking surface 13 with high precision.
In addition, by sinking the immersed tunnel 41 at a predetermined position on the sinking surface 13 with high precision through the above process, it becomes possible to sink the immersed tunnel 41 without requiring a diver to manage the installation precision, etc. Therefore, it becomes possible to reduce the construction cost and the construction period of the immersed tunnel 4.

In addition, in this embodiment, the trench 3 has a trench bottom surface 31 with a flat, even surface at the bottom, which reduces or eliminates the burden of forming the installation guide member 1 using the additive manufacturing device 2, such as adjusting the amount of hydraulic mixture 21 dispensed depending on on-site conditions such as the slope of the trench bottom surface 31 and surface irregularities. This makes it possible to form the installation guide member 1 with more accurate dimensions.

The above describes the installation guide member for an immersed tunnel and the construction method for an immersed tunnel according to this embodiment, but the present invention is not limited to the above embodiment and can be modified as appropriate without departing from the spirit of the invention.

For example, if desired construction and service conditions can be achieved underwater, an additive manufacturing device may be used to eject and layer a hydraulic mixture at a predetermined position to form a roof shape on top of the installation guide member of this embodiment to cover the submerged structure. For example, it may be used as an installation guide member that assists in the installation of submarine cables and protects the surface of the cables. It may also be used in submerged tunnels that connect land and offshore structures (e.g., bottom-fixed offshore wind power generation facilities) and house power lines and signal cables.

REFERENCE SIGNS LIST 1 Installation guide member 11 Bottom plate 12 Guide wall 13 Sinking surface 14 Opposing surface 15 Sinking surface side tip 16 Sinking surface side base end 17 Tapered surface 18 Allowance upper surface 19 Allowance side side 121 Tapered surface side recess 2 Additive manufacturing device 21 Hydraulic mixture 22 Hopper 23 Pump 24 Controller 25 Hose 26 Nozzle (discharge part)
27 Solenoid valve 28 Loading vessel 3 Trench 31 Trench bottom 4 Immersed tunnel 41 Immersed box 42 Immersed box end 43 Hanging mechanism 44 Bulkhead 45 Immersed box tapered surface 46 Protruding portion 47 Lower extension portion 5 Immersed box sinking mechanism 51 Winch-equipped barge (sinking pontoon)
52 Winch control tower (winch tower)
53 Winch 54 Lifting mechanism 55 Wire 6 Backfill surface 7 Joint W Sea W.L. Sea surface B.W. Seabed ground surface U.W.G. Seabed ground L1, L2 Land L.G. Land ground T1, T2 Land tunnel E1, E2 Boundary between land tunnel T1, T2 and sea W

Claims (3)

An installation guide member for an immersed tunnel, which is formed by stacking hydraulic mixtures discharged from a movable discharge portion of an additive manufacturing apparatus having a mechanism for continuously discharging a soft hydraulic mixture from the discharge portion,
A bottom slab having a sinking surface facing the sinking lower surface of the immersed tunnel and stably arranging the immersed tunnel;
A pair of guide walls formed on the sinking surface of the bottom slab at an interval approximately equal to the width of the immersed tunnel;
Equipped with
The pair of guide walls are formed with tapered surfaces that are inclined from the tip of the guide wall toward the base end that contacts the sinking surface of the bottom plate in a direction in which the surfaces approach each other,
The tapered surface and the surface of the immersed tunnel facing the tapered surface are formed by a curved surface having a shape that is approximately the same as that of the immersed tunnel.
Installation guide material for immersed tunnels. A construction method for an immersed tunnel using the installation guide member for the immersed tunnel according to claim 1 ,
Using the additive manufacturing device, the installation guide member is formed on a predetermined water bottom surface on which the immersed tunnel is constructed;
A plurality of immersed tunnel tubes are lowered along the pair of guide walls, and the immersed tunnel tubes are sequentially lowered at predetermined positions on the lowering surface.
After connecting and joining the adjacent immersed tunnels, the water in the immersed tunnels is drained to form the immersed tunnel.
Construction method of immersed tunnel. The predetermined water bottom surface on which the installation guide member is provided is
The water bottom surface is formed to be level so that the bottom plate can be stably placed, and is formed larger than the surface of the bottom plate facing the predetermined water bottom surface.
A method for constructing an immersed tunnel according to claim 2 .

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