A temporary cofferdam and a method for forming a closed-type temporary cofferdam.

Abstract

To provide a temporary cofferdam body and a forming method for a closed type temporary cofferdam body that enable both complete and partial closure of the surroundings of a weir and transmit an axial force caused by water pressure when closed and internally drained, in the circumferential direction.SOLUTION: In temporary cofferdam bodies 100, 200 constructed around a weir pillar 10, an upstream box body 20 and a downstream box body 30 are arranged around the weir pillar 10, there is a first gap 10a at a lateral side of the weir pillar 10, and the upstream box body 20 and the downstream box body 30 respectively comprise an upstream wall body 40 and a downstream wall body 50. By closing the wall bodies 40, 50, a closed type temporary cofferdam body 200 is formed. When the first gap 10a is closed, ends 42, 52 of the wall bodies 40, 50 are connected by a continuing member 80, and an axial force N caused by water pressure P acting on the temporary cofferdam body 200 by draining water between the temporary cofferdam body 200 and the weir pillar 10 is transmitted in the circumferential direction of the temporary cofferdam body 200 via the continuing member 80.SELECTED DRAWING: Figure 8B

Description

Technical Field

[0001] The present invention relates to a temporary closure body and a method for forming a closed temporary closure body.

Background Art

[0002] Among rivers, near the bifurcation points, diversion weirs are provided to divert floods and low water flow plannedly by regulating and restricting the water level. At the estuary (tidal section), tide gates are provided to prevent the intrusion of salt water and maintain the normal function of the flowing water. In addition, intake weirs are provided to take urban water supply, irrigation water, power generation water, etc. by adjusting the water level of the river. Further, regarding the above various types of weirs, those with a height from the foundation ground to the top end of the fixed part of 15 m or more, aiming at flow regulation by storing flowing water and not connected to the levee, are dams. Furthermore, regarding the above various types of weirs, those having the function of a levee and preventing or reducing the flooding of flowing water due to floods and high tides are sluice gates and floodgates. Therefore, in this specification, when referring to a "weir", it shall include the above various types of weirs, dams, sluice gates, floodgates, etc. By the way, the weir provided at the estuary is used to ensure agricultural water, industrial water, etc. by closing the river and shielding the intrusion of seawater, and is also used for flood control purposes to prevent floods and high tides. This weir includes a plurality of weir columns erected at intervals and a main gate (gate leaf) arranged to be vertically movable up and down between adjacent weir columns. The weir columns are erected above, for example, a footing made of reinforced concrete at the bottom of the water to above the water surface, and the main gate is moved up and down by a lifting mechanism provided on the weir columns. In the case of performing repair work or renovation work including seismic reinforcement of the weir columns in a weir provided with weir columns and a main gate, for example, temporary closure is performed to place the periphery of the weir columns in an air working environment with the seawater intrusion prevented by the main gate. Generally, temporary cofferdams are constructed around weir pillars by driving steel sheet piles or building embankments, enclosing the pillars. Water inside these temporary cofferdams is then drained to create an air-based working environment. However, these methods of constructing temporary cofferdams result in large-scale structures, requiring significant time and expense for both construction and subsequent removal. Therefore, in river construction projects where repair work may be limited to dry seasons, this method presents challenges due to the constraints on available working time.

[0003] Here, Patent Document 1 proposes a work box having an opening on its side. In a plan view, this work box accommodates a part of a structure submerged in water through the opening, and in a state where a working space is formed by the work box and the structure, the end of the work box that is attached to the structure and extends in the vertical direction has a first inclined surface that is inclined so that the inside of the working space is narrower and the outside is wider, and a wedge-shaped first water-sealing packing provided in the gap between the structure and the first inclined surface. By moving the first water-sealing packing along the first inclined surface toward the working space and draining water from the working space, water pressure is applied horizontally to the first water-sealing packing, thereby sealing the work box. This method is also called the NDR (Neo-Dry Repair Method) method. On the other hand, Patent Document 2 proposes a caisson for sealing off a structure erected on a base, which is then seated on the submerged base to seal it off. This caisson consists of multiple vertically divided buoyancy-adjustable segmented boxes, with one side of each segmented box connected by hinges to allow opening and closing, a buffer seal material attached continuously to the bottom surface of the cutting edge of each segmented box, support legs protruding from the bottom surface of the cutting edge of each segmented box to support the cutting edge of the segmented box away from the base, and multiple guide spacers protruding laterally from the inside of the segmented box, which can engage with the structure while maintaining a certain distance. By applying this caisson, the segmented boxes constituting the caisson are opened and closed to be fitted onto the structure, the buffer seal material is seated on the base, water-stopping grout is filled along the cutting edge of the caisson, and the water-stopping grout seals the cutting edge of the caisson, thereby sealing it off. This construction method is also known as the RUP (Reinforce & Repair Underwater Pier) method.

[0004] In the temporary cofferdam construction method using a work box described in Patent Document 1, when attempting to construct a temporary cofferdam while blocking the flow of seawater or river water in a weir where a permanent gate extends to the side of a structure such as a weir column, the temporary cofferdam can only be constructed on one side of the permanent gate of the structure. On the other hand, in the temporary cofferdam construction method using a cofferdam caisson described in Patent Document 2, since the target of the temporary cofferdam is a bridge pier, it is not possible to construct a temporary cofferdam while blocking the flow of seawater or river water in a weir where a permanent gate extends to the side of a weir column.

[0005] Incidentally, the timing and frequency of raising and lowering the permanent gates differ between the flood season and the dry season. For example, during the flood season, if the amount of rain flowing upstream increases, there is a possibility that water may intrude into the reclaimed land. Therefore, when the water level upstream of the weir rises above the water level (tidal level) downstream, the permanent gates are opened to release the upstream water downstream. For this reason, if multiple weirs are installed side by side and permanent gates are raised and lowered between adjacent weirs, it is necessary to carry out repair work, etc., in a state where all permanent gates can be raised and lowered (operated). On the other hand, during periods of drought, it is not always necessary to keep all permanent gates operational. Therefore, some permanent gates may be made operational, and for weirs with remaining permanent gates located to the sides, the area around the weir can be completely closed off to carry out repair work. Based on the above, by surrounding the weir with a temporary closure structure that allows for both complete closure of the area around the weir and partial closure of the area around the weir, repair work and other measures can be carried out to accommodate both the flood season and the drought season. However, Patent Documents 1 and 2 do not contain any description of a temporary closure body that allows for complete or partial closure around a weir.

[0006] Patent Document 3 describes a temporary cofferdam that allows for complete and partial closure around a weir. This temporary cofferdam is constructed around a weir pillar in a weir having a weir pillar and a permanent gate that can be raised and lowered and extends to the side of the weir pillar. An upstream box body and a downstream box body are arranged on the upstream and downstream sides around the weir pillar, respectively. There is a first gap on the side of the weir pillar between the two box bodies, and the upstream box body and the downstream box body each have an upstream wall body and a downstream wall body. By closing the walls, the first gap is closed, and a closed-type temporary cofferdam is formed by both box bodies and both walls. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2016-79591 [Patent Document 2] Japanese Patent Application Publication No. 9-189043 [Patent Document 3] Japanese Patent Publication No. 2021-063433 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] According to the temporary cofferdam described in Patent Document 3, it comprises an upstream side wall and a downstream side wall, and a closed-type temporary cofferdam can be formed by closing the upstream side box and the downstream side box. Therefore, if both walls are not closed, the first gap on the side of the weir column will be open, and an open-type temporary cofferdam will be formed. Thus, during the flood season, both walls can be left open without closing them, and the permanent gate on the side of the weir column can be raised and lowered, making it possible to carry out repair work on the area of ​​the weir column surrounded by the upstream side box and the downstream side box. On the other hand, during the dry season, by closing both walls, a closed-type temporary cofferdam can be formed that completely seals off the area around the weir column, making it possible to carry out repair work on the entire area around the weir column.

[0009] Incidentally, after forming a closed-type temporary cofferdam, the water in the internal space between the closed-type temporary cofferdam and the entire circumference of the weir column is drained to make the internal space a dry space, and then repair work on the entire circumference of the weir column is carried out. However, when the internal space is made a dry space, a difference in water head occurs between the river water outside the temporary cofferdam and the internal space, and a large amount of water pressure can act on the temporary cofferdam. Manufacturing a box-shaped structure with a cross-section that can withstand the acting water pressure requires cost and time, and the cross-sectional size of the box-shaped structure may also become large. In this regard, in a closed temporary cofferdam, the water pressure acting on the wall is converted into an axial force (compressive force) in the circumferential direction of the closed temporary cofferdam, and the circumferential compressive force acting on the temporary cofferdam results in a temporary cofferdam with high closure strength, and the cross-sectional size of the box-shaped structure can be set to a reasonable size that can withstand the circumferential compressive force. However, while Patent Document 3 describes closing the upstream and downstream walls, it does not provide any specific description of a means for connecting the ends of the walls while enabling axial force transmission in the circumferential direction of the temporary cofferdam.

[0010] The present invention aims to provide a temporary cofferdam body that enables complete and partial closure around a weir, and that allows the axial force caused by the water pressure acting when the weir is closed and the water inside is drained to be transmitted in the circumferential direction, as well as a method for forming a closed-type temporary cofferdam body. [Means for solving the problem]

[0011] To achieve the aforementioned objective, one embodiment of the temporary cofferdam according to the present invention is: In a weir having a weir pillar and a permanent gate that can be raised and lowered and extends to the side of the weir pillar, Upstream and downstream of the aforementioned weir pillar are arranged an upstream box body and a downstream box body, respectively, and there is a first gap between the two box bodies on the side of the weir pillar. The upstream box and the downstream box each include an upstream wall and a downstream wall that are part of the wall, By closing the aforementioned wall, the first gap is closed, and a closed-type temporary closure body is formed by both of the aforementioned box bodies and both of the aforementioned wall bodies, in a temporary closure body, When the first gap is closed, the ends of the upstream side wall and the downstream side wall are connected by a continuous member, and the axial force caused by the water pressure acting on the temporary cofferdam when the water between the temporary cofferdam and the weir column is drained is transmitted in the circumferential direction of the temporary cofferdam via the continuous member.

[0012] According to this embodiment, when the temporary cofferdam is closed and the first gap is sealed, the ends of the upstream side wall and the downstream side wall are connected by a continuous member, making it possible to transmit the axial force (compressive force) caused by the water pressure acting on the temporary cofferdam when the water between the temporary cofferdam and the weir column is drained, in the circumferential direction of the temporary cofferdam via the continuous member. When both walls are closed, the work of connecting the ends of both walls with a continuous member can be carried out in various ways, such as by having workers or divers operate a continuous member that is pre-installed at the end of one or both ends of the wall to connect it to the end of the other wall, or by having divers insert a continuous member between the ends of both walls to create the connection.

[0013] Furthermore, in another embodiment of the temporary cofferdam according to the present invention, The continuous member is formed by a jack provided on one of the upstream wall and the downstream wall, and a jack support provided on the other. The invention is characterized in that, after the first gap is closed, the jack presses against the jack support, thereby connecting the ends of the upstream wall and the downstream wall.

[0014] According to this embodiment, a continuous member is formed by a jack at the end of one wall and a jack receiver at the end of the other wall, and the ends of both wall bodies become continuous when the jack presses against the jack receiver, thereby smoothly and reliably forming a continuous structure between the ends of both wall bodies. Here, while giraffe jacks and hydraulic jacks can be used, if the jack and jack receiver are on the outside of the wall, the jack will extend underwater, so it is preferable to use a method where, for example, a diver turns the handle of a giraffe jack to extend it. Furthermore, by providing multiple sets of corresponding jack and jack receiver combinations (units) at vertically spaced intervals at the ends of both wall bodies, it becomes possible to effectively transmit axial force to the circumferential direction of the temporary cofferdam throughout the entire wall body.

[0015] Furthermore, in another embodiment of the temporary cofferdam according to the present invention, The continuous member is formed by a female nut fixed to one or both of the upstream side wall and the downstream side wall, and a male bolt that is screwed into the female nut. The first gap is closed, after which the male bolt is rotated and slides toward the other wall body to become continuous with the other wall body.

[0016] According to this embodiment, a continuous member is formed by a female nut fixed to the end of one or both wall bodies and a male bolt screwed into the female nut. The tip of the male bolt slides along the female nut and presses against the end of the other wall body, thereby connecting the ends of both wall bodies and creating a continuous structure between the ends of both wall bodies smoothly and reliably. In addition to the rotation of the male bolt being manually performed by an operator, a diver, or the like, a motor may be equipped at the end of the male bolt, and a method of driving the motor by remote control may be applied. Also in this form, a plurality of continuous members formed by the female nut and the male bolt are provided at intervals in the vertical direction at the end of at least one of the wall bodies, so that the axial force can be effectively transmitted in the circumferential direction of the temporary fastening body over the entire area of the wall body.

[0017] Moreover, in another aspect of the temporary fastening body according to the present invention, the continuous member is formed by one or more block-shaped or plate-shaped first plugging materials that close a second gap between the ends of the upstream wall body and the downstream wall body, after the first gap is closed, one or more of the first plugging materials are inserted into the second gap, and the upstream wall body and the downstream wall body are continuous through the first plugging material.

[0018] According to this aspect, the continuous member is a block-shaped or plate-shaped first plugging material that closes the second gap between the wall bodies, and the wall bodies are made continuous by inserting one or more first plugging materials into the second gap, so that a continuous structure between the ends of both wall bodies can be formed smoothly and surely. For example, by applying a plurality of plate-shaped first plugging materials with different thicknesses, after first inserting a relatively thick first plugging material into the second gap, and then inserting a first plugging material with a thickness that can be inserted into the remaining gap, rapid plugging can be realized. Here, a relatively thick first plugging material may be pre-attached to the end of one of the wall bodies. Also, by providing a tapered surface or a curved surface that tapers towards the front in the insertion direction of the block-shaped or plate-shaped first plugging material, easy insertion into a slight gap of the first plugging material can be realized. Also in this form, for example, a plurality of continuous members formed by a plurality of first plugging materials are inserted at intervals in the vertical direction at the ends of both wall bodies, so that the axial force can be effectively transmitted in the circumferential direction of the temporary fastening body over the entire area of the wall body.

[0019] Furthermore, in another embodiment of the temporary cofferdam according to the present invention, The continuous member is formed by one or more second gap-filling members that close the second gap between the ends of the upstream box body and the downstream box body. The second gap-filling material comprises a bag and a fluid contained inside the bag. The first gap is closed, after which one or more of the second gap-filling materials are inserted into the second gap, and the upstream side wall and the downstream side wall are connected via the second gap-filling materials.

[0020] According to this embodiment, the continuous member is formed by a second gap-filling material that closes the second gap between the wall bodies, and the second gap-filling material comprises a bag and a fluid contained inside the bag, and by inserting one or more second gap-filling materials into the second gap, the wall bodies are connected to each other, thereby smoothly and reliably forming a continuous structure between the ends of both wall bodies. The fluid contained within the bag may include fresh mortar or concrete, as well as other liquids such as water or oil. When the fluid is mortar or concrete, its deformability allows for smooth insertion into the second gap. As time passes after insertion, the mortar hardens, and the hard second filler material presses against the ends of both wall sections, forming a continuous structure between them. In this configuration as well, for example, by inserting multiple continuous members formed by several second filler members at vertical intervals at the ends of both wall bodies, it becomes possible to effectively transmit axial force to the circumferential direction of the temporary cofferdam throughout the entire wall body.

[0021] Furthermore, in another embodiment of the temporary cofferdam according to the present invention, When the first gap is closed, wall support pillars are erected on the weir side of both opposing ends of the upstream and downstream wall bodies. The contact areas at the ends of both the upstream and downstream wall bodies contact the contact area of ​​the wall support column to form a closed position of the first gap. A water-sealing material is provided in at least one of the contact area and the area to be contacted.

[0022] According to this embodiment, the contact areas at the ends of both wall bodies contact the contact area of ​​the wall support column erected on the weir column side to form a closed position of the first gap, and a water-sealing material is provided in at least one of the contact area and the contact area, so that the water-sealing material is crushed by the water pressure acting on both wall bodies, a water-sealing structure is formed between the end of the wall body and the wall support column, while allowing the transmission of axial force between the ends of the wall bodies. Here, by applying continuous waterproofing material above and below the ends of the wall and the support columns for the wall, the inside of the closed temporary cofferdam can be completely sealed off from the surrounding river water.

[0023] Furthermore, one aspect of the method for forming a closed-type temporary closure body according to the present invention is: In a weir having a weir pillar and a permanent gate that can be raised and lowered and extends to the side of the weir pillar, Upstream and downstream of the aforementioned weir pillar are arranged an upstream box body and a downstream box body, respectively, and there is a first gap between the two box bodies on the side of the weir pillar. The upstream box and the downstream box each include an upstream wall and a downstream wall that are part of the wall, A method for forming a closed-type temporary cofferdam, wherein the first gap is closed by closing the wall, and the two box bodies and both wall bodies form a closed-type temporary cofferdam, After closing the first gap, the ends of the upstream side wall and the downstream side wall are connected by a continuous member, and the axial force caused by the water pressure acting on the temporary cofferdam is transmitted to the circumferential direction of the temporary cofferdam via the continuous member by draining the water between the temporary cofferdam and the weir column.

[0024] According to this embodiment, after the temporary cofferdam is closed and the first gap is sealed, the ends of the upstream side wall and the downstream side wall are connected by a continuous member, thereby forming a closed-type temporary cofferdam that can transmit the axial force (compressive force) caused by the water pressure acting on the temporary cofferdam when the water between the temporary cofferdam and the weir column is drained in the circumferential direction of the temporary cofferdam via the continuous member. [Effects of the Invention]

[0025] The present invention provides a temporary cofferdam body and a method for forming a closed-type temporary cofferdam body that enable complete and partial closure of the area around a weir, and that allow the axial force caused by the water pressure acting when the weir is closed and the water inside is drained to be transmitted in the circumferential direction. [Brief explanation of the drawing]

[0026] [Figure 1] This figure illustrates an example of a method for installing a temporary cofferdam according to an embodiment. [Figure 2] This is a perspective view of an example of an open-type temporary cofferdam, which is included in an example of a temporary cofferdam according to the embodiment. [Figure 3] This is a perspective view of an example of a closed-type temporary cofferdam, which is included in an example of a temporary cofferdam according to the embodiment. [Figure 4] This is a perspective view showing a temporary gate attached to the side of a closed-type temporary cofferdam. [Figure 5] (a) to (c) are process diagrams illustrating the construction process of the method for forming a closed-type temporary cofferdam according to the embodiment, up to the point where the ends of the wall bodies are connected with a continuous member. [Figure 6] Following Figure 5, (a) to (c) are process diagrams illustrating the construction process of the method for forming a closed-type temporary cofferdam according to the embodiment, up to the point where the ends of the wall bodies are connected with a continuous member. [Figure 7] Figure 6(c) is a view in the direction of arrow VII, and is a front view of the closed upstream and downstream side walls. [Figure 8A]Figure 7 is a view taken in the direction of arrow VIII, showing an example of a continuous member, and depicts the state before the continuous member connects the ends of both wall bodies. [Figure 8B] An example of a continuous member is shown in the diagram, where the ends of both wall sections are connected. [Figure 9] This is a plan view of a weir pillar and a closed-type temporary cofferdam, illustrating the state in which axial force is transmitted in the circumferential direction of the temporary cofferdam. [Figure 10A] This diagram shows another example of a continuous member, illustrating the state before the continuous member connects the ends of both wall bodies. [Figure 10B] Another example of a continuous member is shown in the diagram where the ends of both wall sections are connected. [Figure 11A] This figure shows yet another example of a continuous member, illustrating the state before the continuous member connects the ends of both wall bodies. [Figure 11B] Another example of a continuous member is a diagram showing the ends of both wall bodies connected to each other. [Figure 12A] This figure shows yet another example of a continuous member, illustrating the state before the continuous member connects the ends of both wall bodies. [Figure 12B] Another example of a continuous member is a diagram showing the ends of both wall bodies connected to each other. [Modes for carrying out the invention]

[0027] The temporary cofferdam body and the method for forming the closed-type temporary cofferdam body according to the embodiment will be described below with reference to the attached drawings. In this specification and drawings, substantially identical components may be denoted by the same reference numerals to avoid redundant explanations.

[0028] [A temporary cofferdam body according to an embodiment, and a method for forming a closed-type temporary cofferdam body] Referring to Figures 1 to 12, an example of a temporary cofferdam body according to the embodiment and an example of a method for forming a closed-type temporary cofferdam body will be described. Here, Figure 1 is a diagram illustrating an example of a method for installing a temporary cofferdam body according to the embodiment. Figure 2 is a perspective view of an example of an open-type temporary cofferdam body included in the example of a temporary cofferdam body according to the embodiment, Figure 3 is a perspective view of an example of a closed-type temporary cofferdam body included in the example of a temporary cofferdam body according to the embodiment, and Figure 4 is a perspective view showing a state in which a temporary gate is attached to the side of a closed-type temporary cofferdam body. Furthermore, Figures 5(a) to (c) and 6(a) to (c) are process diagrams illustrating an example of a method for forming a closed-type temporary cofferdam body according to the embodiment, in order.

[0029] As shown in Figure 1, the weir pillar 10, which is repaired or refurbished while under an air-based working environment with a temporary cofferdam constructed, forms a weir 1 (estuary weir). This repair is, for example, reinforcement work using a continuous fiber wrapping method, which is part of seismic reinforcement measures to prevent the loss of agricultural water sources and salt damage due to damage to sluice gates during large-scale earthquakes. In the illustrated example, an estuary weir is used as an example of weir 1, but weirs include diversion weirs, tidal barriers, intake weirs, and even dams, sluice gates, and culverts. Therefore, the temporary cofferdam body according to this embodiment can be applied to repair work on various weirs. Furthermore, the temporary cofferdam body according to this embodiment can be applied not only to weir repair work, but also to the repair work on various underwater structures such as bridge abutments and piers located underwater, when temporarily coffering around them.

[0030] The weir 1 comprises a plurality of weir pillars 10 arranged at intervals in the width direction of the river mouth, and a permanent gate 14 (gate door) that is raised and lowered by a lifting mechanism 16 of an adjacent weir pillar 10.

[0031] Furthermore, as shown in Figure 2, there is a reinforced concrete base 15 at the bottom of the water, and a weir column 10 is erected above the base 15 up to the water surface. A permanent gate drop-in groove 12 is provided on the side 11 of the weir column 10 into which the end of the permanent gate (not shown) is loosely fitted, and a first drop-in groove 13 is provided at a position away from the permanent gate drop-in groove 12 into which a temporary gate 73 (see Figure 5) is dropped.

[0032] The following outline describes the process for transporting and installing the box-shaped structures 20 and other components that make up the temporary cofferdam around the weir pillar 10. First, the lower box-shaped structure 21 and upper box-shaped structures 22 and 23 (see Figure 2), which are manufactured at the factory, are loaded onto trucks and transported by land to a pier (not shown) which serves as the work yard. A float barge 330, part of which is shown in Figure 1, is moored at the pier, and heavy machinery on the pier first lowers the lower box-shaped structure 21 into the inlet 331. Above the lower box-shaped structure 21 that has been lowered into the inlet 331, the heavy machinery sequentially lowers the upper box-shaped structures 22 and 23, and the lower box-shaped structure 21 and the upper box-shaped structures 22 and 23 are connected to each other to form the box-shaped structure 20.

[0033] This connection work can be carried out using the float barge 330 as a work platform. In addition, during the process of forming the box body 20, the draft of the box body 20 can be adjusted as desired by continuously pouring external water into the hollow part of the lower box body 21. The box body 20 formed in the inlet 331 is temporarily fixed to the inlet 331, and the float barge 330 is towed to the weir pillar 10 to be constructed using a tugboat (not shown).

[0034] Next, the float barge 330, which has been towed to the weir pillar 10 to be constructed, is moored via several mooring wires (not shown). In the construction area shown in the example, there is a management road or the like, which is a head-restricting obstacle 400, above the weir pillar 10, and the box body 20 is installed relative to the weir pillar 10 while preventing interference with this head-restricting obstacle 400. More specifically, as shown in Figure 1, after mooring the float barge 330 near the weir pillar 10, the draft is adjusted so that the box body 20 does not interfere with the head-restricting obstacle 400, and the box body 20 is lowered to the desired Y1 direction prior to installation.

[0035] Next, in the inlet 331 of the float barge 330, the return winch 332 and the outgoing winch 333 are used to adjust the posture of the box body 20 by moving it back and forth in the Y2 direction using wires 334 and 335 attached between them and the box body 20, and the box body 20 is installed on the weir column 10 while housing a part of the weir column 10 inside the box body 20 through the opening 26 provided in the box body 20. Here, although not shown in the diagram, another box body 30 is also transported to the weir column 10 in the same manner and installed around the weir column 10.

[0036] According to the installation method (construction direction) described above, an open-type temporary cofferdam 100 as shown in Figure 2 is installed. Upstream box body 20 and downstream box body 30 are arranged on the upstream and downstream sides of the side 11 of the weir column 10, respectively, and there is a first gap 10a on the sides of the weir column 10 between the two box bodies 20 and 30 (on the left and right sides of the weir column 10). Both the upstream box body 20 and the downstream box body 30 are roughly U-shaped in plan view, and both ends of the weir column 10 are housed inside 25 and 35 respectively through openings 26 and 36 at their respective ends and attached to the weir column 10.

[0037] Here, "upstream side" and "downstream side" can mean various things depending on the location of the weir in question, such as the lake side and the bay side, the river side and the sea side, or the mountain side and the sea side of a river.

[0038] The upstream box body 20 and the downstream box body 30 are equipped with rotatable upstream wall body 40 and downstream wall body 50 at openings 26 and 36 at their respective ends. Figure 2 shows an open-type temporary cofferdam 100 with the upstream wall body 40 and downstream wall body 50 in an open state.

[0039] The upstream box body 20 has a three-tiered structure, consisting of a lower box body 21 positioned at the bottom and multiple upper box bodies 22 and 23 (two in the illustrated example) mounted on top of the lower box body 21, with the lower box body 21 and the upper box bodies 22 and 23 being interconnected. A wave pressure resistance panel 24 is attached to the top surface of the uppermost box body 23.

[0040] On the other hand, the downstream box body 30 also has a three-tiered structure, consisting of a lower box body 31 positioned at the bottom and multiple upper box bodies 32 and 33 (two in the illustrated example) mounted on top of the lower box body 31, with the lower box body 31 and the upper box bodies 32 and 33 being interconnected. Furthermore, a wave pressure resistance panel 34 is attached to the top surface of the uppermost box body 33.

[0041] The box bodies 20 and 30 may have one or more upper box bodies in addition to the illustrated example, and may be a single-piece structure rather than a stacked structure.

[0042] Multiple bracing beams 62, which constitute the temporary support structure 60, are stretched between the side surface 11 of the weir column 10 and the box bodies 20 and 30. More specifically, multiple support columns 61 are erected at intervals along the inner wall surfaces of the box bodies 20 and 30, with opposing support columns 61 forming pairs, and bracing beams 62 are stretched between the pairs of support columns 61. In addition, near the side surface 11 of the weir column 10, a support column 63 is erected with a small third gap 69 between it and the side surface 11 of the weir column 10, and bracing beams 62 are stretched between this support column 63 and the corresponding support column 61 erected on the inner wall surface.

[0043] Then, a short brace 64 is placed in the small third gap 69 and spans between the support column 63 and the side surface 11 of the weir column 10. The support columns 61, 63 and the brace 62 are formed from shaped steel materials such as H-shaped steel, and the brace 62 is equipped with jacks (not shown) such as giraffe jacks at its intermediate positions and ends. The short brace 64 is formed from shaped steel materials such as short H-shaped steel, steel pipes, or cylindrical pipes, and may similarly be equipped with jacks (not shown). By operating the jacks, axial force is introduced to the brace 62, allowing the opposing support columns 61, 63 to resist the external water pressure acting on the box bodies 20, 30, and the box bodies 20, 30 are fixed to the side surface 11 of the weir column 10 by the brace 62 and the corresponding short brace 64.

[0044] The support columns 63 included in the temporary shoring 60 are erected near the weir columns 10 with a third gap 69 between them and the side surface 11 of the weir columns 10. Short bracing beams 64 are placed between the support columns 63 and the weir columns 10 in the third gap 69. When repairing the side surface 11 of the weir columns 10, a portion of the short bracing beams 64 can be moved to create a working space in the third gap 69. Therefore, the length of the short bracing beams 64 is set to a length that can secure the necessary working space.

[0045] According to the configuration of the temporary support structure 60 shown in the illustration, when the bracing becomes an obstacle during repairs to the side surface 11 of the weir column 10, it is not necessary to replace the long bracing, and only the short bracing 64 needs to be replaced. Therefore, repairs to the weir column 10 can be carried out efficiently without making major changes to the temporary support structure 60.

[0046] The opening joints 20' and 30' located on the sides of the respective openings 26 and 36 of the box bodies 20 and 30 are removed when forming the closed-type temporary cofferdam 200 shown in Figure 3. As shown in Figure 3, in the areas where the opening joints 20' and 30' have been removed, opening reinforcing columns 65 that support the box bodies 20 and 30, and opening reinforcing short bracing beams 66 that connect the opening reinforcing columns 65 to the side surface 11 of the weir column 10 are provided.

[0047] Corresponding wall bodies 40 and 50 are rotatably attached to the box bodies 20 and 30 via a plurality of hinge mechanisms 41 and 51.

[0048] Since the walls 40 and 50 are rotatably attached to each of the box bodies 20 and 30, the walls 40 and 50 can be smoothly closed (as shown in Figure 3) and opened (as shown in Figure 2) by rotating. Furthermore, since the walls 40 and 50 rotate on the outside of the box bodies 20 and 30, the rotation of the walls 40 and 50 does not affect repair work inside the box bodies 20 and 30.

[0049] Furthermore, the opening and closing configuration of the walls 40 and 50 relative to the box bodies 20 and 30 may also be as shown in the illustrated example. In addition, the walls 40 and 50 may be slidably stored in both box bodies 20 and 30 toward the first gap 10a, with the first gap 10a being opened when the walls 40 and 50 are stored, and the first gap 10a being closed when the walls 40 and 50 slide out. Moreover, there may be a manual configuration in which the walls 40 and 50 are towed toward the first gap 10a and the first gap 10a is closed by attaching the walls 40 and 50 to both box bodies 20 and 30 using heavy machinery or divers.

[0050] As shown in Figure 3, in the closed-type temporary cofferdam 200, temporary support structures are also constructed between the ends of both wall bodies 40 and 50 and the sides of the weir columns 10. Specifically, wall support columns 67 are erected so as to straddle the inner surfaces of both wall bodies 40 and 50, and short wall support braces 68 are placed between the wall support columns 67 and the sides 11 of the weir columns 10.

[0051] In this way, the bracing beams 62 and short bracing beams 64 that constitute the temporary support structure 60 are stretched between the side surface 11 of the weir column 10 and the box bodies 20 and 30, thereby allowing the box bodies 20 and 30 to be stably fixed around the weir column 10. Furthermore, in the closed-type temporary cofferdam 200, short bracing beams 68 for supporting the walls that constitute the temporary support structure are also stretched between both wall bodies 40 and 50 and the weir column 10, thereby allowing the wall bodies 40 and 50 to be stably fixed to the weir column 10.

[0052] Furthermore, as shown in Figure 4, in the closed-type temporary cofferdam 200, a temporary gate 73 is attached to either the upstream wall 40 or the downstream wall 50 (in the illustrated example, to the side of the upstream wall 40).

[0053] More specifically, multiple temporary support columns 71 are erected on the sides of the upstream wall 40 at intervals, each having a second recessed groove 72 on both sides. These temporary support columns 71 are formed, for example, from H-shaped steel, and the second recessed groove 72 is formed by the web and two flanges.

[0054] The temporary gate 73 is formed as a single unit by connecting multiple (three in the illustrated example) corner-cutting members 74, 75 to each other via connecting hardware 76. The two lower corner-cutting members 74 are, for example, existing corner-cutting members, and the upper corner-cutting member 75 is, for example, a new corner-cutting member. The number of corner-cutting members is not limited to the illustrated example, and furthermore, all corner-cutting members may be new corner-cutting members. A suspension hook 75a is provided on the upper surface of the new corner-cutting member 75 to which the lower end of a suspension member 79 hanging from a traction device 78 is secured.

[0055] Furthermore, end support steel members 46 are erected on the side of the wall 40, and the end face of the temporary gate 73 at the wall-side end is supported by the end support steel members 46. A third drop-in groove 47 is provided on the side of the wall 40, and the end of the temporary gate 73 at the wall-side end is dropped into the third drop-in groove 47.

[0056] During the flood season, the open-type temporary cofferdam 100 shown in Figure 2 is formed, which opens the first gap 10a, allowing the permanent gate 14 to be raised and lowered, and enabling repair work to be carried out on the area of ​​the weir pillar 10 that is surrounded by the upstream box body 20 and the downstream box body 30.

[0057] On the other hand, during periods of drought, by closing both wall bodies 40 and 50, a closed-type temporary cofferdam 200 is formed that completely seals off the area around the side 11 of the weir column 10, thereby enabling repair work to be carried out over the entire area around the weir column 10.

[0058] Furthermore, as shown in Figure 4, a temporary gate 73 can be attached to either the upstream wall 40 or the downstream wall 50. For example, by attaching the temporary gate 73 to the side of the closed-type temporary blockage 200, the flow of seawater or river water between the upstream and downstream sides can be blocked by the temporary gate 73 even when the permanent gate 14 is open (in the raised position).

[0059] Next, referring to Figures 5 and 6, a series of steps in the method for forming a closed-type temporary cofferdam according to the embodiment, up to the point of connecting the ends of the wall bodies with a continuous member, will be described. The details of connecting the ends of the wall bodies with a continuous member will be explained below with reference to Figures 7 to 12.

[0060] In the method for forming a closed-type temporary cofferdam, first, as shown in Figure 5(a), an upstream box body 20 is placed on the upstream side and a downstream box body 30 is placed on the downstream side around the side surface 11 of the weir column 10, and a first gap 10a is provided between the two box bodies 20 and 30. In addition, temporary support structures 60 are installed inside each of the box bodies 20 and 30, and by fixing the box bodies 20 and 30 to the side surface 11 of the weir column 10, an open-type temporary cofferdam 100 is constructed.

[0061] Next, in order to enable the permanent gate 14 to be raised and lowered, a wall support column 67 is erected on the upstream side of the first gap 10a that does not interfere with the permanent gate 14, and the wall support column 67 and the side surface 11 of the weir column 10 are connected by a short wall support brace 68.

[0062] After connecting the wall support column 67 and the side surface 11 of the weir column 10 with a short wall support brace 68, as shown in Figure 5(b), the upstream wall 40 is rotated in the X1 direction to extend into the first gap 10a, and the end of the upstream wall 40 is connected to the wall support column 67 that constitutes the temporary shoring.

[0063] Next, as shown in Figure 5(c), the temporary gate 73 is lowered into the third drop-in groove 47 provided on the inner surface of the upstream wall 40 and the corresponding first drop-in groove 13 of the weir column 10.

[0064] Furthermore, end support steel members 46 are erected on the outside of the upstream wall 40, and after erecting multiple temporary support columns 71 at intervals, the temporary gate 73 is dropped into the third drop-in groove 47 provided on the outer surface of the upstream wall 40 and the second drop-in groove 72 provided in the adjacent temporary support column 71.

[0065] Furthermore, by dropping the temporary gates 73 into the second drop-in grooves 72 of both adjacent temporary support columns 71, a continuous set of temporary gates 73 is constructed on the side of the side 11 of the weir column 10.

[0066] Next, as shown in Figure 6(a), the permanent gate 14 is raised, and as shown in Figure 6(b), the downstream wall 50 is rotated in the X2 direction to extend into the first gap 10a, and the end of the downstream wall 50 is connected to the wall support column 67 that constitutes the temporary shoring, thereby closing the first gap 10a with both walls 40 and 50, and constructing a closed-type temporary cofferdam 200 composed of both box bodies 20 and 30 and both walls 40 and 50.

[0067] Furthermore, after the closed-type temporary cofferdam 200 is constructed, as shown in Figure 6(b), repositioning opening reinforcement pillars 65 and opening reinforcement short bracing beams 66 are installed on the sides of the opening joints 20' and 30'. Next, as shown in Figure 6(c), water is drained from the wall interior space formed by the side surface 11 of the weir column 10, both wall bodies 40 and 50, and the opening joints 20' and 30', and the opening joints 20' and 30' are removed, thereby connecting the entire circumferential surface of the side surface 11 of the weir column 10.

[0068] In the drainage work described above, a method may be applied in which water is poured into the interior of the box bodies 20 and 30 to balance the water pressure from the box bodies 20 and 30 with the water pressure from the internal space of the wall body on the opening joints 20' and 30', and then opening reinforcing support columns 65 and short opening reinforcing braces 66 for repositioning are installed on the sides of the opening joints 20' and 30', the opening joints 20' and 30' are removed, and water is drained from the box bodies 20 and 30 and the internal space of the wall body.

[0069] According to the illustrated method for forming a closed-type temporary cofferdam, after the closed-type temporary cofferdam 200 is formed, water is drained from the internal space of the wall and the opening joints 20' and 30' are removed, thereby creating a dry space between the closed-type temporary cofferdam 200 and the entire circumference of the side surface 11 of the weir column 10, allowing repair work to be carried out on the entire circumference of the side surface 11 of the weir column 10.

[0070] Furthermore, for example, during a dry season, in the state shown in Figure 5(a), only the area of ​​the side 11 of the weir pillar 10, which is surrounded by both box bodies 20 and 30, can be made a dry space, allowing for repair and other construction work to be carried out.

[0071] Next, with reference to Figures 7 to 12, a method for forming a closed-type temporary cofferdam, specifically a method of connecting the ends of the wall bodies with a continuous member, will be described. Here, Figure 7 is a view in direction VII of Figure 6(c), and is a front view of the closed upstream and downstream wall bodies. Figure 8A is a view in direction VIII of Figure 7, and shows an example of a continuous member, illustrating the state before the continuous member connects the ends of both wall bodies. Figure 8B shows the state after the example of the continuous member has connected the ends of both wall bodies. Furthermore, Figure 9 is a plan view of the weir column and the closed-type temporary cofferdam, illustrating the state in which axial force is transmitted in the circumferential direction of the temporary cofferdam.

[0072] As shown in Figure 7, the ends 42 and 52 of the upstream and downstream walls 40 and 50 close together, thereby closing the first gap 10a and forming a closed-type temporary cofferdam 200 with both box bodies 20 and 30 and both walls 40 and 50.

[0073] At the ends 42 and 52 of the wall bodies 40 and 50, multiple end continuous areas A are set at intervals in the vertical direction (four in the illustrated example), and the continuous structure of the wall bodies 40 and 50 is formed by the continuous members provided in each end continuous area A. Below, we will explain the multiple examples of continuous members shown in Figures 8, 10 to 12, and the continuous structure of the ends 42 and 52 formed by each of these continuous members.

[0074] The continuous member 80 shown in Figure 8 is formed by a jack 81 provided at the end 52 of the wall 50 and a jack receiver 82 provided at the end 42 of the wall 40. Both the jack 81 and the jack receiver 82 are fixed to the outer surfaces of the walls 50 and 40 by bolts 83. Here, the jack 81 may be provided at the end 42 and the jack receiver 82 may be provided at the end 52. Also, in the four continuous end areas A in the vertical direction, the ends on which the jack 81 and jack receiver 82 are installed may be alternately arranged.

[0075] Wall support columns 67, formed from H-shaped steel, are erected on the weir side of the ends 42 and 52 of both wall bodies 40 and 50, and the lower ends of the wall support columns 67 are fixed to the base plate 15 by anchor bolts (not shown), for example.

[0076] A short bracing beam 68 for wall support is connected to one flange of the wall support column 67, and the other end of the short bracing beam 68 for wall support is connected to the side surface of the weir column 10. As shown in the figure, strip-shaped waterproofing material 85 extending vertically from the ends 42 and 52 of both walls 40 and 50 is fixed to the contact areas 42a and 52a of the ends 42 and 52 by bolts or the like, and both waterproofing materials 85 come into contact with the contact area 67a of the other flange of the wall support column 67. Here, the waterproofing material 85 is formed by a gasket or the like. The waterproofing material 85 may also be provided in the contact area 67a of the wall support column 67. Alternatively, the waterproofing material 85 may be provided in both the contact areas 42a and 52a of the ends 42 and 52 and the contact area 67a of the wall support column 67.

[0077] The jack 81 in the illustrated example is a giraffe jack, and by rotating the hand crank 81a, a portion of the jack 81 extends. For example, a diver (not shown) submerges himself in the river water outside the walls 40 and 50 and rotates the hand crank 81a, causing a portion of the jack 81 to extend toward the jack receiver 82 in the Z1 direction, as shown in Figure 8B, and come into contact with the jack receiver 82, forming a continuous structure of the ends 42 and 52 of the walls 40 and 50 via the continuous member 80.

[0078] Subsequently, by draining the water from the interiors 25 and 35 of the walls 40 and 50, a water head difference is created between the inside and outside of the walls 40 and 50, and a water pressure P acts on the walls 40 and 50 from the outside. At this time, since the closed-type temporary cofferdam 200 has a structure in which the entire circumference is completely closed as shown in Figure 9, the acting water pressure P is converted into an axial force N (compressive force) in the circumferential direction of the temporary cofferdam 200. Then, in the continuous structure of the ends 42 and 52 of the walls 40 and 50, the axial force N is transmitted via the continuous member 80.

[0079] Furthermore, the water pressure P causes the water-stopping material 85 to be pressed against the contact area 67a, forming a water-stopping structure with excellent sealing properties.

[0080] In this continuous structure, as shown in Figure 7, four sets of corresponding jack 81 and jack receiver 82 combinations (units) are provided at vertically spaced intervals at the ends 52 and 42 of both wall bodies 50 and 40. This makes it possible to effectively transmit the axial force N to the circumferential direction of the temporary cofferdam 200 over the entire vertical range of the wall bodies 50 and 40.

[0081] Furthermore, although the acting water pressure P acts on the wall support columns 67 via the ends 42 and 52 of the wall bodies 40 and 50, the wall support columns 67 can take a reaction force on the side of the weir column 10 via the short bracing 68 for wall support, so that the continuous structure of the ends 42 and 52 of the wall bodies 40 and 50 can be stably supported against the water pressure P.

[0082] On the other hand, the continuous member 80A shown in Figure 10 is formed by a plurality of female nuts 86 (two in the illustrated example) fixed to the end 52 of the wall body 50, and male bolts 87 that are slidably screwed into each female nut 86. As shown in Figure 7, two continuous members 80A shown in Figure 10 are provided in each of the four end continuous areas A. Here, although not shown, the continuous member 80A may be provided at the end 42 of the wall body 40, or one of the two continuous members 80A may be provided at the end 52 of the wall body 50 and the other at the end 42 of the wall body 40. Furthermore, a pair of continuous members 80A may be provided at corresponding positions at both ends 42, 52 of the wall bodies 40 and 50 (a configuration in which a total of four continuous members 80A are provided in two pairs).

[0083] As shown in Figure 10B, when a worker or diver rotates the male bolt 87 with a rotary tool, the male bolt 87 slides in the Z2 direction toward the end 42 of the other wall body 40 and comes into contact with the end 42, forming a continuous structure of the ends 42 and 52 of the wall bodies 40 and 50 via the continuous member 80A.

[0084] Although not shown in the diagram, a motor may be attached to one end of each male bolt 87, and the male bolts 87 may be automatically rotated by driving the motor remotely.

[0085] On the other hand, the continuous member 80B shown in Figure 11 is formed by a plurality of plate-shaped first gap fillers 88a, 88b, and 88c of different thicknesses. As shown in Figure 11A, for example, the first gap filler 88a, which is relatively thicker, is first inserted into the second gap 70 in the Z3 direction, then the next thickest first gap filler 88b is inserted into the remaining gap in the Z4 direction, and then the thinnest first gap filler 88c is inserted in the Z5 direction. As shown in Figure 11B, the second gap 70 is closed by the three types of first gap fillers 88a, 88b, and 88c, and a continuous structure is formed at the ends 42, 52 of the wall bodies 40, 50 via the continuous member 80B.

[0086] Although not shown in the diagram, the first filler material may be in block form. Alternatively, a relatively thicker first filler material 88a may be pre-attached to, for example, the end 42, and the other first filler materials 88b and 88c may be inserted sequentially. Furthermore, a tapered or curved surface may be provided in front of the first filler material in the insertion direction, and this tapered shape allows for easy insertion of the first filler material into small gaps.

[0087] On the other hand, the continuous member 80C shown in Figure 12 is formed by a bag 89a and a fluid 89b contained within the bag 89a. Here, the fluid 89b includes fresh mortar or concrete, as well as liquids such as water or oil.

[0088] As shown in Figure 12A, when a diver or the like pushes and inserts the continuous member 80C into the second gap 70 in the Z6 direction, the second gap 70 is closed by the continuous member 80C, as shown in Figure 12B, and a continuous structure is formed at the ends 42, 52 of the wall bodies 40, 50 via the continuous member 80C.

[0089] If the fluid 89b is mortar or concrete, its deformability allows for smooth insertion into the second gap 70. As time passes after insertion, the mortar hardens, and the hard second filler 80C presses against the ends 42 and 52 of both wall bodies 40 and 50, forming a continuous structure between them.

[0090] Regardless of which of the continuous members 80, 80A, 80B, or 80C described above is applied, a continuous structure can be smoothly and reliably formed between the ends 42 and 52 of the wall bodies 40 and 50, and the axial force N caused by the acting water pressure P can be transmitted to the circumferential direction of the temporary cofferdam 200 via the continuous members 80, 80A, 80B, and 80C. As a result, a temporary cofferdam 200 with high closure strength can be formed, and the cross-sections of the wall bodies 40 and 50 can be set to a reasonable size that can withstand circumferential compressive forces.

[0091] Other embodiments may be possible, such as those combining other components with the configurations listed in the above embodiments, and the present invention is not limited in any way to the configurations shown herein. In this regard, modifications can be made without departing from the spirit of the present invention, and can be appropriately determined according to the application form. [Explanation of Symbols]

[0092] 1: Weir (estuary weir) 10:Weir pillar 10a: First gap 11: Side view 12: Permanent gate drop-in groove 13: First drop-in groove 14: Permanent Gate 15: Bottom board 16: Lifting mechanism 20: Upstream box body (box body) 20': Opening joint 21:Lower box body 22: Upper box (second box) 23: Upper box (third box) 24: Wave pressure resistance panel 25: Inside 26:Aperture 30: Downstream box (box) 30': Opening joint 31:Lower box body 32: Upper box (second box) 33: Upper box (third box) 34: Wave pressure resistance panel 35: Inside 36:Aperture 40: Upstream wall (wall) 41: Hinge mechanism 42: End 42a: Contact area 46: End support steel 47: Third drop-in groove 50: Downstream wall (wall) 51: Hinge mechanism 52: End 52a: Contact area 60: Temporary support work 61: Strut 62:Surface beam 63: Post 64: Short bracing 65: Opening reinforcement support column 66: Short bracing for opening reinforcement 67: Wall support column 67a:Abutted area 68: Short bracing for wall support 69: Third Gap 70: Second gap 71: Temporary support 72: Second recess groove 73: Temporary gate 74: Existing corner-cut lumber (corner-cut lumber) 75: Newly installed corner-cut timber (corner-cut timber) 75a: Hanging hook 76: Connecting hardware 80, 80A, 80B, 80C: Continuous members 81: Giraffe Jack (Jack) 81a: Hand crank 82: Jack receiver 83: Bolt 85: Waterproofing material 86: Female nut 87: Male bolt 88a, 88b, 88c: First gap filler material 89a: Bag (Second gap filling material) 89b: Fluid (second gap filler) 100: Open-type temporary cofferdam (temporary cofferdam) 200: Closed-type temporary cofferdam (temporary cofferdam) 330: Float barge 331: Inlet 332: Pull-back winch 333: Feed-out winch 334,335: Wire 400: Air head restriction obstacle (management road) W: External water (seawater, river water) A: End continuous area P: Water pressure N: Axial force

Claims

1. In a weir having a weir pillar and a permanent gate that can be raised and lowered and extends to the side of the weir pillar, Upstream and downstream of the aforementioned weir pillar, an upstream box body and a downstream box body, respectively, are arranged on the upstream and downstream sides of the box body, and there is a first gap between the two box bodies on the side of the weir pillar. The upstream box and the downstream box each include an upstream wall and a downstream wall that are part of the wall, By closing the aforementioned wall, the first gap is closed, and a closed-type temporary closure body is formed by both of the aforementioned box bodies and both of the aforementioned wall bodies, When the first gap is closed, the ends of the upstream side wall and the downstream side wall are connected by a continuous member, and the axial force caused by the water pressure acting on the temporary cofferdam when the water between the temporary cofferdam and the weir column is drained is transmitted in the circumferential direction of the temporary cofferdam via the continuous member. The continuous member is formed by a jack provided on one of the upstream wall and the downstream wall, and a jack support provided on the other. A temporary cofferdam, characterized in that, after the first gap is closed, the ends of the upstream side wall and the downstream side wall are connected by the jack pressing against the jack support.

2. A weir having a weir column and a permanent gate that is movable up and down and extends to the side of the weir column, Upstream and downstream of the aforementioned weir pillar, an upstream box body and a downstream box body, respectively, are arranged on the upstream and downstream sides of the box body, and there is a first gap between the two box bodies on the side of the weir pillar. The upstream box and the downstream box each include an upstream wall and a downstream wall that are part of the wall, By closing the aforementioned wall, the first gap is closed, and a closed-type temporary closure body is formed by both of the aforementioned box bodies and both of the aforementioned wall bodies, When the first gap is closed, the ends of the upstream side wall and the downstream side wall are connected by a continuous member, and the axial force caused by the water pressure acting on the temporary cofferdam when the water between the temporary cofferdam and the weir column is drained is transmitted in the circumferential direction of the temporary cofferdam via the continuous member. The continuous member is formed by a female nut fixed to one or both of the upstream side wall and the downstream side wall, and a male bolt that is screwed into the female nut. A temporary cofferdam, characterized in that, after the first gap is closed, the male bolt is rotated and slides toward the other wall body to become continuous with the other wall body.

3. When the first gap is closed, wall support pillars are erected on the weir side of both opposing ends of the upstream and downstream wall bodies. The contact areas at the ends of both the upstream and downstream wall bodies contact the contact area of ​​the wall support column to form a closed position of the first gap. The temporary cofferdam according to claim 1 or 2, characterized in that a water-sealing material is provided in at least one of the contact area and the contacted area.

4. In a weir having a weir pillar and a permanent gate that can be raised and lowered and extends to the side of the weir pillar, Upstream and downstream of the aforementioned weir pillar, an upstream box body and a downstream box body, respectively, are arranged on the upstream and downstream sides of the box body, and there is a first gap between the two box bodies on the side of the weir pillar. The upstream box and the downstream box each include an upstream wall and a downstream wall that are part of the wall, A method for forming a closed-type temporary cofferdam, wherein the first gap is closed by closing the wall, and the two box bodies and both wall bodies form a closed-type temporary cofferdam, A method for forming a closed-type temporary cofferdam, characterized in that, after closing the first gap, the ends of the upstream side wall and the downstream side wall are connected by a continuous member, and the axial force caused by the water pressure acting on the temporary cofferdam by draining the water between the temporary cofferdam and the weir column is transmitted in the circumferential direction of the temporary cofferdam via the continuous member, wherein the continuous member is formed by a jack provided on one of the upstream side wall and the downstream side wall and a jack receiver provided on the other, and after closing the first gap, the ends of the upstream side wall and the downstream side wall are connected by the jack pressing against the jack receiver.

5. A weir having a weir column and a permanent gate that can be raised and lowered and extends to the side of the weir column, Upstream and downstream of the aforementioned weir pillar, an upstream box body and a downstream box body, respectively, are arranged on the upstream and downstream sides of the box body, and there is a first gap between the two box bodies on the side of the weir pillar. The upstream box and the downstream box each include an upstream wall and a downstream wall that are part of the wall, A method for forming a closed-type temporary cofferdam, wherein the first gap is closed by closing the wall, and the two box bodies and both wall bodies form a closed-type temporary cofferdam, A method for forming a closed-type temporary cofferdam, characterized in that, after closing the first gap, the ends of the upstream side wall and the downstream side wall are connected by a continuous member, and the axial force caused by the water pressure acting on the temporary cofferdam by draining the water between the temporary cofferdam and the weir column is transmitted in the circumferential direction of the temporary cofferdam via the continuous member, wherein the continuous member is formed by a female nut fixed to one or both of the upstream side wall and the downstream side wall, and a male bolt screwed into the female nut, and after closing the first gap, the male bolt is rotated and slid toward the other wall, thereby connecting it to the other wall.

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