Temporary cofferdam construction method inside culverts

Abstract

To provide a temporary cofferdam construction method in a culvert that enables construction of a concrete structure in a culvert where water level is always present in a dry environment in a short time at low cost. [Solution] This method for constructing a dry area by sealing off the water with a temporary cofferdam when carrying out underwater construction work inside a concrete structure that is a culvert where the water level is always maintained includes a top plate opening process in which an opening is formed in the top plate of the concrete structure that is the culvert to serve as an entrance / exit for materials and equipment; a bracket scaffolding installation process in which a bracket scaffolding is installed below the entrance / exit; a temporary cofferdam assembly and lowering process in which temporary cofferdam panel materials are assembled on the bracket scaffolding using the chain block and the assembled panel materials are lowered by their own weight, repeating this process until they hit the ground inside the culvert; and a temporary cofferdam drainage process in which water is drained from inside the temporary cofferdam using a submersible pump.

Description

[Technical Field]

[0001] The present invention relates to a temporary cofferdam construction method for culverts, and more particularly to a temporary cofferdam construction method for culverts when performing earthquake-resistant reinforcement on the inner walls of culverts such as water diversion channels and underground structures that always have a water level inside. [Background technology]

[0002] In the past, when carrying out investigations, inspections, repairs, and reinforcement work such as seismic reinforcement of the inner walls of culverts with a water level, such as diversion channels and underground structures, it was necessary to somehow drain the water from the culvert and lower the water level as much as possible before carrying out the work. However, lowering the water level requires a great deal of labor and time, such as pumping, which increases the construction cost. For this reason, there is a strong demand for a temporary cofferdam construction method inside a culvert that can be carried out quickly and at low cost.

[0003] Patent Document 1 also discloses a temporary cofferdam construction method for existing underwater structures developed by the applicant. The temporary cofferdam construction method for existing underwater structures described in Patent Document 1 is a temporary cofferdam construction method for existing underwater structures in which an existing underwater structure such as a bridge pier P is enclosed with a temporary cofferdam construction body 1, the interior of which is drained, and main construction is carried out, and includes a reaction bracket installation step in which a reaction bracket 3 is installed on the top of the existing underwater structure to obtain a reaction force from the existing underwater structure when the temporary cofferdam construction body 1 is pressed into the underwater ground; The temporary closing body 1 is pressed into the underwater ground by a pressure vessel 4, and the underwater ground inside the temporary closing body 1 is excavated. The temporary closing body 1 is lowered while being guided by a guide bracket 8' having a roller member 8a' or a sliding member at the tip that contacts the temporary closing body 1 (see claim 1 in the claims of Patent Document 1, paragraphs

[0022] to

[0055] of the specification, Figures 1 to 21 of the drawings, etc.).

[0004] However, although the temporary cofferdam construction method for existing underwater structures described in Patent Document 1 can be applied to existing underwater structures such as bridge piers P, it cannot be applied directly to concrete structures inside culverts.

[0005] Furthermore, Patent Document 2 discloses a method for repairing and replacing a flexible joint of a culvert after displacement, in which the existing flexible joint 20 is removed, a reference plane 31 is set for attaching a new flexible joint 30 to the displaced culvert, connecting bolts 32 are connected to the existing mounting bolts 15 of the mounting frames 14, 14 in accordance with this reference plane 31, and then raising members 34 are attached and fixed via these connecting bolts 32 in accordance with the reference plane 31, and the new flexible joint 30 is assembled to these raising members 34 and protected with protective members 38, 39 (see claim 1 in the scope of claims of Patent Document 2, paragraphs

[0024] to

[0043] of the specification, and Figures 1 to 11 of the drawings, etc.).

[0006] However, the repair and replacement method of a flexible joint of a culvert described in Patent Document 2 is a method of replacing a flexible joint inside the culvert, and is not applicable to reinforcement work of concrete structures, etc. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 6010070 [Patent Document 2] Japanese Patent Application Laid-Open No. 2010-106534 Summary of the Invention [Problem to be solved by the invention]

[0008] Therefore, the present invention has been devised in consideration of the above-mentioned problems, and its object is to provide a temporary cofferdam construction method in a culvert that enables construction of a concrete structure in a culvert where water level is always present in a dry environment in a short time at low cost. [Means for solving the problem]

[0009] The temporary cofferdam construction method in a culvert according to the first invention is a temporary cofferdam construction method in a culvert that uses a temporary cofferdam to drain the water and create a dry area when performing underwater construction work in a concrete structure that is a culvert where the water level is always maintained, and is characterized by comprising: a top plate opening process in which an opening is formed in the top plate of the concrete structure that is the culvert to serve as an entrance and exit for materials and equipment; a hanging scaffolding installation process in which a hanging scaffolding is installed at a predetermined height from the underside of the top plate; an overhead traveling crane installation process in which a trolley-type manual or electric chain block that can travel on rails as an overhead traveling crane is installed using the hanging scaffold; a temporary cofferdam assembly and lowering process in which temporary cofferdam panel materials are assembled using the chain block and the assembled panel materials are lowered by their own weight, repeating this process until they hit the ground inside the culvert; and a temporary cofferdam drainage process in which water is drained from inside the temporary cofferdam using a submersible pump.

[0010] The temporary cofferdam construction method in a culvert according to the second invention is characterized in that, in the first invention, it includes a temporary cofferdam press-in process in which, after the temporary cofferdam panel material has landed on the ground, the panel material is pressed in with a hydraulic jack using the reaction force from the top plate.

[0011] The temporary cofferdam construction method in a culvert according to the third invention is characterized in that, in the first invention, it comprises a hanging scaffolding installation step of installing a hanging scaffolding at a predetermined height from the underside of the top plate, and an overhead traveling crane installation step of using the hanging scaffolding to install a trolley-type manual or electric chain block that can travel on rails as an overhead traveling crane.

[0012] The temporary cofferdam construction method in a culvert according to a fourth invention is characterized in that, in the third invention, after the overhead traveling crane installation step, the suspended scaffolding is lowered to perform the temporary cofferdam assembly lowering step.

[0013] The temporary cofferdam construction method in a culvert according to the fifth invention is characterized in that, in the first or second invention, it includes a temporary cofferdam guide material installation step of installing a temporary cofferdam guide material that guides the downward or pressing-in direction of the panel material.

[0014] The temporary cofferdam construction method in a culvert according to the sixth invention is characterized in that, in the first or second invention, it includes a waterproof concrete pouring step of pouring concrete at the lower end of the panel material to stop water.

[0015] The temporary cofferdam construction method in a culvert according to the seventh invention is characterized in that, in the first or second invention, it includes an intra-cofferdam dredging step of dredging soil and sand from within the temporary cofferdam and discharging it outside the temporary cofferdam.

[0016] The temporary cofferdam construction method in a culvert according to the eighth invention is the same as that of the first invention, wherein in the top plate opening step, a core drilling machine is used to drill a plurality of core holes through which wire saws are inserted at predetermined positions in the top plate, and the openings are cut using the wire saws inserted into the core holes.

[0017] The temporary cofferdam construction method in a culvert according to the ninth invention is characterized in that in the first invention, in the top plate opening step, the opening is formed by drilling a series of core holes in the top plate with a core drilling machine. [Effects of the Invention]

[0018] According to the first to ninth inventions, temporary cofferdam can be reliably established and construction of a concrete structure in a culvert where water level is always present can be carried out in a dry environment, so construction can be carried out efficiently in a short time at low cost.

[0019] In particular, according to the second invention, the panel material is pressed in with a hydraulic jack, utilizing the reaction force from the top plate, so that even if the bottom end of the assembled temporary cofferdam panel material does not descend under its own weight after hitting the ground inside the culvert, temporary cofferdam can be reliably performed and a dry area can be constructed.

[0020] In particular, according to the third invention, since it includes a suspended scaffolding installation process and an overhead traveling crane installation process, work can be carried out using the suspended scaffolding and the overhead traveling crane, which significantly improves the work efficiency of each task in the subsequent processes.

[0021] In particular, according to the fourth invention, the suspension scaffolding is lowered to carry out the cofferdam assembly lowering process, so the scaffolding can be brought close to the water surface, making the cofferdam assembly work easier and allowing the cofferdam assembly work to be carried out efficiently in a short time.

[0022] In particular, according to the fifth invention, a guide material for the temporary cofferdam is installed to guide the lowering or pressing-in direction of the panel material, so that the lowering or pressing-in work of the temporary cofferdam can be carried out accurately, and these work can be carried out efficiently in a short time.

[0023] In particular, according to the sixth aspect of the present invention, waterproof concrete is poured, so that the bottom end of the cofferdam can be completely waterproofed, and drainage work can be carried out in a short time to create a dry area.

[0024] In particular, according to the seventh invention, the soil and sand within the temporary cofferdam is dredged and removed outside the temporary cofferdam, so that the soil and sand can be easily removed from the dry area to be constructed in a short time, thereby improving the work efficiency of subsequent processes.

[0025] In particular, according to the eighth and ninth aspects of the invention, the opening can be formed easily and in a short time. [Brief explanation of the drawings]

[0026] [Figure 1] FIG. 1 is a vertical cross-sectional view of a diversion channel showing a portion to be temporarily cofferdammed by a temporary cofferdam method in a culvert according to this embodiment. [Figure 2] FIG. 2 is a flowchart showing the construction flow of the temporary cofferdam construction method in the culvert according to this embodiment. [Figure 3] Figure 3(a) is a plan view showing a method for opening an entrance / exit for materials and equipment in the top plate of a diversion channel in the channel top plate opening process of the temporary cofferdam construction method in a culvert according to this embodiment, and Figure 3(b) is a plan view showing a method for opening a manhole in the top plate of the diversion channel. [Figure 4] FIG. 4 is a plan view showing a method for opening an entrance for carrying in and out materials and equipment in the top plate of the diversion channel, which is different from that shown in FIG. 3(a). [Figure 5]FIG. 5 is a process explanatory diagram showing a bracket scaffolding installation process for the temporary cofferdam construction method in a culvert according to this embodiment. [Figure 6] FIG. 6 is a process explanatory diagram showing the process of installing a suspended scaffold for the temporary cofferdam construction method in the same culvert. [Figure 7] FIG. 7 is a process explanatory diagram showing the overhead traveling crane installation process for the temporary cofferdam construction method in the culvert. [Figure 8] FIG. 8 is a process explanatory diagram showing the process of lowering the suspended scaffolding in the temporary cofferdam construction method in the same culvert. [Figure 9] FIG. 9 is a process explanatory diagram showing the process of installing a temporary cofferdam guide material in the temporary cofferdam construction method in the culvert. [Figure 10] FIG. 10 is a process explanatory diagram showing the cofferdam assembly lowering process of the cofferdam construction method in the culvert. [Figure 11] FIG. 11 is a process explanatory diagram showing the cofferdam press-in process of the cofferdam construction method in the culvert. [Figure 12] FIG. 12 is a process explanatory diagram showing the process of constructing the temporary cofferdam water upper portion in the temporary cofferdam construction method in the same culvert. [Figure 13] FIG. 13 is a process explanatory diagram showing the process of constructing the temporary cofferdam water upper part in the temporary cofferdam construction method in the same culvert. [Figure 14] FIG. 14 is a process explanatory diagram showing the waterproof concrete pouring process of the temporary cofferdam construction method in the culvert. [Figure 15] FIG. 15 is a process explanatory diagram showing the process of draining water inside the temporary cofferdam and replacing struts in the temporary cofferdam construction method in the culvert. [Figure 16] FIG. 16 is a process explanatory diagram showing the process of installing scaffolding inside the temporary cofferdam in the temporary cofferdam construction method inside the culvert. [Figure 17] FIG. 17 is a process explanatory diagram showing the reinforcement process of the temporary cofferdam method in the culvert. [Figure 18] FIG. 18 is a process explanatory diagram showing the process of removing the scaffolding inside the temporary cofferdam in the temporary cofferdam construction method inside the culvert. [Figure 19] FIG. 19 is a process explanatory diagram showing the process of pouring water into the cofferdam and installing guide materials in the cofferdam construction method in the same culvert. [Figure 20]FIG. 20 is a process explanatory diagram showing the process of removing the water portion of the temporary cofferdam in the temporary cofferdam construction method in the same culvert. [Figure 21] FIG. 21 is a process explanatory diagram showing the process of removing the underwater part of the temporary cofferdam in the temporary cofferdam construction method in the same culvert. [Figure 22] FIG. 22 is a process explanatory diagram showing the process of removing the temporary cofferdam guide material in the temporary cofferdam construction method in the culvert. [Figure 23] FIG. 23 is a process explanatory diagram showing the process of installing an overhang scaffold for the temporary cofferdam construction method in the same culvert. [Figure 24] FIG. 24 is a process explanatory diagram showing the process of removing the overhead traveling crane in the temporary cofferdam construction method in the same culvert. [Figure 25] FIG. 25 is a process explanatory diagram showing the process of removing the suspended scaffolding and bracket scaffolding of the temporary cofferdam construction method in the culvert. DETAILED DESCRIPTION OF THE INVENTION

[0027] Hereinafter, an embodiment of a temporary cofferdam construction method in a culvert according to the present invention will be described in detail with reference to the drawings.

[0028] [Temporary cofferdam construction method inside culverts] A temporary cofferdam construction method for an underdrain according to an embodiment of the present invention will be described using Figures 1 to 25. An example will be described in which a temporary cofferdam is constructed around the base of a central underdrain wall 11 where the water level is located in a diversion channel 10 having both left and right banks that has become a culvert as shown in Figure 1, and a dry area is constructed to carry out reinforcement work.

[0029] Figure 1 is a vertical cross-sectional view of a diversion channel showing the target portion of the culvert to be temporarily cofferdammed using the temporary cofferdam method according to this embodiment. As shown in Figure 1, the diversion channel 10, an existing concrete structure that is the target of the reinforcement work, has a central culvert wall 11, which is the target portion of the reinforcement work, and is a concrete structure with a culvert that is equipped with a top slab 12 and a bottom slab 13, and whose vertical cross-sections on the diversion channel left bank wall 14 side and the diversion channel right bank wall 15 side are divided into left and right banks.

[0030] (preparation process) Fig. 2 is a flowchart showing the overall construction flow of the reinforcement work (hereinafter referred to as the main work) of the central culvert wall 11 of the diversion channel 10 shown in Fig. 1, including the temporary cofferdam work method in the culvert according to this embodiment. As shown in Fig. 2, the main work involves a site survey as a preparatory process, as well as preparation of the equipment and material delivery point, installation of public relations signs, and necessary removal work.

[0031] (Temporary construction process) Next, the construction work will involve the temporary construction process of preparing the work yard, followed by the permanent belt installation process, in which a permanent belt will be installed. The necessary earthworks (excavation and retaining works) will then be carried out, and the culvert lighting installation process will be carried out, in which lighting equipment will be installed inside the culvert.

[0032] (Top plate opening process) Next, in this construction work, a top plate opening process is carried out, in which an opening (loading entrance 2) with a specified opening area of ​​approximately 3m x 2m is cut into the culvert, which serves as an entrance and exit for materials and equipment, as part of the temporary cofferdam construction method within the culvert according to this embodiment.

[0033] Specifically, first, an excavation process is carried out in which an excavator such as a backhoe is used to excavate until the top slab 12 of the diversion channel 10, which is a concrete structure shown in Fig. 1, is exposed. The excavated soil is loaded onto a transport vehicle such as a 4-ton dump truck and transported / carried out.

[0034] Figure 3(a) is a plan view showing a method for opening an entrance / exit for materials and equipment in the top plate of the diversion channel in the top plate opening process of the temporary cofferdam construction method in the culvert according to this embodiment, and Figure 3(b) is a plan view showing a method for opening a manhole in the top plate of the diversion channel.

[0035] As shown in Figure 3(a), in this top plate opening process, core drilling and a wire saw are used in combination to cut the top plate 12 (600 mm to 900 mm thick) of the diversion channel 10 into a rectangular shape in plan view to open the equipment and material transport entrance 2. In this process, first, a core drilling machine is used to drill multiple core holes with a diameter of 50 mm as wire saw guide holes 2a for guiding the wire saw to predetermined positions in the top plate 12 of the diversion channel 10 where the concrete portion is exposed, and a core drilling machine is used to drill multiple core holes with a diameter of 100 mm as suspension holes 2b.

[0036] Thereafter, as shown by the thick line in Figure 3(a), a wire saw is inserted between the wire saw guide holes 2a and rotated to cut and divide the block into 1m x 1m squares that can be lifted by a lifting machine such as a 4.9 ton crane. The aforementioned hanging holes 2b are drilled in two places for each 1m x 1m square reinforced concrete block with a thickness of 600mm to 900mm so that it can be lifted by a lifting machine.

[0037] As shown in Figure 3(b), the manhole 3, which is circular in plan view and serves as an entrance for people to climb up and down, is formed by drilling multiple core holes 3a with a diameter of 150 mm using a core drilling machine so that the outer peripheries of the core holes 3a overlap. This is because it is difficult to cut a circular shape in plan view using a wire saw.

[0038] Figure 4 is a plan view showing a method for opening an access point for materials and equipment in the top slab 12 of the diversion channel 10, different from that shown in Figure 3(a). As shown in Figure 4, in this opening cutting process, an opening (access point 2) with a predetermined opening area of ​​approximately 3m x 2m may be formed by drilling a series of 150mm diameter core holes 3a with a core drilling machine without using a wire saw. However, a dry construction method is preferable to prevent muddy water from being scattered into the diversion channel 10. Also, instead of drilling the suspension holes 2b, a suspension jig 3b may be connected to a 1m x 1m square reinforced concrete block with post-installed anchor bolts and then lifted.

[0039] However, prior to completing the top plate opening work using the wire saw and drilling a 150 mm diameter core hole, a fall prevention fence will be installed using the drilled core hole to prevent workers from falling through the opening (carry-in / out entrance 2).

[0040] (Opening reinforcement process) Next, in this construction work, an opening reinforcement process is carried out as part of the temporary cofferdam construction method for the culvert according to this embodiment. In this opening reinforcement process, concrete holes are drilled in the top slab 12 of the water distribution channel 10 along the peripheral edge of the loading / unloading entrance 2 opened in the previous process using a drilling machine such as a hammer drill, and anchor bolts are fixed into the drilled holes using post-installed anchors such as Chemical Anchor (registered trademark), and the area is reinforced with H-shaped steel beams. In this opening reinforcement process, the periphery of the manhole 3 is also reinforced in a similar manner by assembling H-shaped steel beams in a rectangular shape.

[0041] (Bracket scaffolding installation process) Next, as shown in Fig. 5, in this construction, as part of the temporary cofferdam construction method in a culvert according to this embodiment, a bracket scaffolding installation process is carried out to install bracket scaffolding directly below the loading / unloading entrance 2. Fig. 5 is a process explanatory diagram showing the bracket scaffolding installation process of the temporary cofferdam construction method in a culvert according to this embodiment.

[0042] Specifically, first, a framework scaffolding is assembled on the ground, and then the assembled framework scaffolding is hoisted from the loading / unloading entrance 2 using a lifting machine such as a crane, and carried into the diversion channel 10, where a scaffolding (not shown) is constructed above the water level during construction of the diversion channel 10. In addition, lighting equipment is installed along the central culvert wall 11 by diver D1.

[0043] Next, using the delivered framework scaffolding, holes are drilled with a drilling machine such as a hammer drill in the side concrete of the central culvert wall 11 directly below the loading / unloading entrance 2. Anchor bolts are then installed in the drilled holes, fixed in place with post-installed anchors such as Chemical Anchor (registered trademark). After that, the positions of the installed anchor bolts are measured and marked on the vertical members (vertical members 4a) of the bracket scaffolding 4, and holes are drilled with an electric drill (metal drilling machine) such as an Atra.

[0044] Meanwhile, each material for the bracket scaffolding 4 is brought in through the loading / unloading entrance 2, and the vertical members 4a, diagonal members 4b, and horizontal members 4c are secured in this order with mounting bolts. The scaffolding boards are then placed on the brackets and secured with annealed iron wire. After the bracket scaffolding is assembled, the frame scaffolding is dismantled and removed, and carried out through the loading / unloading entrance 2.

[0045] (Hanging scaffolding installation process) Next, as shown in Figure 6, in this work, as part of the temporary cofferdam construction method inside a culvert according to this embodiment, a hanging scaffolding installation process is carried out in which a pre-floor construction type floor-type system hanging scaffolding manufactured by Nisso Industries is used to install the hanging scaffolding 5 inside the water distribution channel 10 at a height of about 1500 mm from the underside (ceiling surface) of the top slab 12. Figure 6 is a process explanatory diagram showing the hanging scaffolding installation process of the temporary cofferdam construction method inside a culvert according to this embodiment.

[0046] Specifically, the first side of the suspended scaffolding 5 is assembled using the bracket scaffolding 4 installed in the previous process, and all subsequent work is done in the air by hand using the assembled suspended scaffolding 5. First, using the bracket scaffolding 4, suspension bolts B1 are attached to the underside (ceiling surface) of the top plate 12. Then, the scaffolding components for the suspended scaffolding 5 are manually carried in through the loading / unloading entrance 2, and the suspended scaffolding 5 is assembled by hand, side by side, in the correct order, starting from the side furthest from the central culvert wall 11, using the suspension bolts B1.

[0047] The portion of the suspended scaffolding 5 used for assembling the running rails will be an overhanging scaffolding 5a that does not require support by the suspension bolts B1, and will be promptly removed after the running rails are assembled.

[0048] In addition, in order to prevent the suspended scaffolding 5 from being washed away due to a sudden rise in water level caused by a sudden downpour, an electric chain block is attached in advance and the control panel is installed outside the diversion channel 10 and operated from outside so that the suspended scaffolding 5 can be raised easily and safely.

[0049] (Overhead crane installation process) Next, as shown in Figure 7, in this work, as part of the temporary cofferdam construction method in a culvert according to this embodiment, an overhead traveling crane installation process is carried out in which rails R1 for the overhead traveling crane and a trolley-type manual or electric chain hoist CB that can run on the rails as an overhead traveling crane are installed on the underside (ceiling surface) of the top slab 12 in the diversion channel 10 using the above-mentioned suspended scaffolding 5. Figure 7 is a process explanatory diagram showing the overhead traveling crane installation process in the temporary cofferdam construction method in a culvert according to this embodiment.

[0050] Specifically, worker W1 drives anchor bolts into the underside (ceiling surface) of the top slab 12 from suspended scaffolding 5, and then fixes rails R1 made of H-shaped steel (for example, H-250 x 250) brought in from the loading / unloading entrance 2 to the anchor bolts. In the illustrated embodiment, three rails R1 are installed, and are used respectively for lateral movement of materials, temporary support for cofferdams, and temporary support for guide steel materials and struts.

[0051] Before drilling the anchor bolts, a rebar search is carried out, and holes are drilled into the concrete on the underside of the top slab 12, avoiding the rebar. After cleaning the holes, the bolts are fixed in place with post-installed anchors such as resin anchors. The positions of the anchor bolts are also marked on rail R1, which is made of H-shaped steel, and holes are drilled in rail R1 at the marked positions with an electric drill. The drilled holes are then used to fix rail R1 to the underside of the top slab 12 with anchor bolts.

[0052] (Scaffolding lowering process) Next, as shown in Fig. 8, in this construction, a hanging scaffolding lowering process is carried out to lower the hanging scaffolding 5 as part of the temporary cofferdam construction method in a culvert according to this embodiment. Fig. 8 is a process explanatory diagram showing the hanging scaffolding lowering process of the temporary cofferdam construction method in a culvert according to this embodiment.

[0053] Considering the efficiency of the temporary cofferdam assembly and press-in work described below, the hanging scaffolding 5 is lowered to a height of approximately 500 mm above the water level during construction in the diversion channel 10. In addition, the bracket scaffolding 4 and the overhanging scaffolding 5a are dismantled and removed because they interfere with the temporary cofferdam assembly.

[0054] (Temporary cofferdam guide material installation process) Next, as shown in Fig. 9, in this work, as part of the temporary cofferdam construction method in a culvert according to this embodiment, a temporary cofferdam guide material installation process is carried out in which temporary cofferdam guide materials 6 that guide the downward or press-in direction of panel materials 7, which will be described later, are installed on the central culvert wall 11, which is the target of the reinforcement work. Fig. 9 is a process explanatory diagram showing the temporary cofferdam guide material installation process in the temporary cofferdam construction method in a culvert according to this embodiment.

[0055] In this temporary cofferdam guide material installation process, guide material 6 made of steel is fixed in the vertical direction along the central culvert wall 11 with post-installed anchors. Furthermore, the guide material 6 above the construction water level is fixed by worker W1 from suspended scaffolding 5, and the guide material 6 below the construction water level is fixed by diver D1 with the assistance of worker W1. The steel for the guide material 6 is brought in from the delivery entrance 2 using a lifting machine such as a crane.

[0056] (Cofferdam assembly lowering process) Next, as shown in Figure 10, in this construction, as part of the temporary cofferdam construction method in a culvert according to this embodiment, a temporary cofferdam assembly and lowering process is carried out in which temporary cofferdam panel materials are repeatedly assembled and lowered until they hit the ground in the culvert (earth and sand accumulated in the diversion channel 10). Figure 10 is a process explanatory diagram showing the temporary cofferdam assembly and lowering process of the temporary cofferdam construction method in a culvert according to this embodiment.

[0057] In this temporary cofferdam assembly and lowering process, the temporary cofferdam panel materials 7 are brought in one by one from the loading / unloading entrance 2 using a lifting machine such as a crane, then transferred to a chain block CB for lateral movement and assembled from the back, repeatedly allowing them to sink under their own weight until they hit the ground inside the culvert during construction. The panels 7 are connected together by fastening them with bolts using rubber gaskets, with the assistance of diver D1 underwater inside the culvert.

[0058] After assembly of one lot is complete, it is lowered using a temporary electric chain hoist CB, and the next lot of steel panel material 7 is assembled in the same way. The lowering is done carefully while maintaining horizontality. In addition, the guide material 6, waling 8a, and strut 8b are assembled after each lot of temporary cofferdam to be installed is assembled. This assembly and sinking due to its own weight is repeated until it hits the ground of the diversion channel 10.

[0059] (Cofferdam press-in process) Next, as shown in Figure 11, in this construction, as part of the temporary cofferdam construction method in a culvert according to this embodiment, if the lower end of the assembled panel material 7 does not descend under its own weight after it hits the ground in the culvert, a temporary cofferdam press-in process is carried out in which the panel material is pressed in until it reaches the bottom slab 13. Figure 11 is a process explanatory diagram showing the temporary cofferdam press-in process of the temporary cofferdam construction method in a culvert according to this embodiment.

[0060] Specifically, if the weight of the temporary cofferdam panel material 7 does not cause it to sink to the top of the bottom slab 13, the reaction force from the top slab 12 of the existing diversion channel 10 is used to press the panel material downward along the guide material 6 with a hydraulic jack, keeping the distance to the central culvert wall 11 constant using the struts 8b. This hydraulic unit is installed outside the diversion channel 10, and hydraulic hoses are run to the jack. The hydraulic jack is fixed to the top of the temporary cofferdam panel material 7 using a jig such as a bullman.

[0061] If there are any areas that do not sink even after being pressed in, this may be due to an obstruction, so this is checked by diver D1. After 500 mm of pressing in, diver D1 will carry out excavation within the cofferdam. After excavation is complete, diver D1 will check to see if the top of the bottom slab 13 has been reached.

[0062] Furthermore, if an abnormal increase in water level is expected during the aforementioned temporary cofferdam guide material installation process, temporary cofferdam assembly lowering process, and temporary cofferdam press-in process, the temporary cofferdam panel material 7 will be inserted into the ground and the suspended scaffolding 5 will be raised to a safe height.

[0063] (Temporary cofferdam water upper construction process) Next, as shown in Fig. 12, in this construction work, as part of the temporary cofferdam construction method in a culvert according to this embodiment, a temporary cofferdam water upper section construction process is carried out to construct the water upper section of the temporary cofferdam panel material 7 that was pressed in up to the top of the base slab 13 in the previous process. Fig. 12 is a process explanatory diagram showing the temporary cofferdam water upper section construction process in the temporary cofferdam construction method in a culvert according to this embodiment.

[0064] As shown in FIG. 12, the underwater part of the cofferdam panel material 7 is assembled on the suspended scaffolding 5.

[0065] (Dredging process inside the cofferdam) Next, as shown in Figure 13, in this construction, as part of the temporary cofferdam construction method in a culvert according to this embodiment, an inner cofferdam dredging process is carried out in which soil and sand inside the cofferdam are dredged and removed outside the cofferdam. Figure 13 is a process explanatory diagram showing the inner cofferdam dredging process of the temporary cofferdam construction method in a culvert according to this embodiment.

[0066] In the dredging process inside the cofferdam, diver D1 uses a horizontal sand pump P to suck up the soil and sand from inside the cofferdam (on the central culvert wall 11 side) through suction hose H1, and then discharges it outside the cofferdam through drainage hose H2. This sand pump P is brought in through the loading / unloading entrance 2 with the suction hose H1 and drainage hose H2 connected, and is then hung from an electric chain hoist CB and installed inside the cofferdam panel material 7. The nozzle of the drainage hose H2 of the sand pump P is fixed to the cofferdam etc. so that it does not move around. Furthermore, the soil and sand inside the cofferdam is reliably removed so that waterproof concrete can be poured in the subsequent process.

[0067] (Water-stopping concrete pouring process) Next, as shown in Fig. 14, in this construction, as part of the temporary cofferdam construction method in a culvert according to this embodiment, a waterproof concrete pouring process is carried out in which concrete is poured using a pump truck to stop water at the bottom end of the temporary cofferdam panel material 7. Fig. 14 is a process explanatory diagram showing the waterproof concrete pouring process of the temporary cofferdam construction method in a culvert according to this embodiment.

[0068] First, in this waterproof concrete pouring process, diver D1 installs a steel form for the waterproof concrete to prevent it from shifting, and then diver D1 drives anchor bolts into the top of the bottom slab 13 of the diversion channel 10 to secure it in place. The pump truck's pressure hose is inserted through the delivery / exit entrance 2, and diver D1 carefully pours the concrete by holding the nozzle of the pressure hose. The formwork is dismantled in the air after draining the water from the cofferdam. The gable end of the cofferdam on the central culvert wall 11 side is waterproofed with mortar or caulking material. However, if the top of the bottom slab 13 is smooth, it is also possible to waterproof the bottom of the panel material 7 by directly fixing it to the bottom slab 13 of the diversion channel 10 with angle bars, without pouring the waterproof concrete.

[0069] (Drainage within the temporary cofferdam and replacement of strut beams) Next, as shown in Figure 15, in this construction, as part of the temporary cofferdam construction method in a culvert according to this embodiment, a submersible pump is used to drain water from inside the cofferdam, and a process of draining water inside the cofferdam and replacing the strut is carried out, in which the guide material 6 is removed and the strut 8b is replaced. Figure 15 is a process explanatory diagram showing the process of draining water inside the cofferdam and replacing the strut in the temporary cofferdam construction method in a culvert according to this embodiment.

[0070] Specifically, a general submersible pump is used to drain water from inside the cofferdam on the central culvert wall 11 side to outside the cofferdam. Then, after the waterproof concrete has cured, diver D1 replaces the guide material 6 and struts 8b. At this time, the struts 8b are installed above the reinforcement area. The guide material 6 and struts 8b are replaced one by one, from the upper level to the lower level, and the struts 8b are installed immediately after the guide material 6 is removed. The struts 8b are then fixed to the central culvert wall 11 by driving anchor bolts. After the first level of struts 8b has been installed, the water level inside the cofferdam is lowered by a submersible pump to just below the second level of struts 8b.

[0071] (Scaffolding installation process inside the cofferdam) Next, as shown in Figure 16, in this work, as part of the temporary cofferdam construction method in a culvert according to this embodiment, a scaffolding installation process is carried out in which temporary scaffolding is installed in the temporary cofferdam that has been drained in the previous process. Figure 16 is a process explanatory diagram showing the scaffolding installation process in the temporary cofferdam of the temporary cofferdam construction method in a culvert according to this embodiment.

[0072] In this process of installing scaffolding within the cofferdam, temporary scaffolding such as frame scaffolding and wedge scaffolding is assembled and installed within the cofferdam, which was made into a dry area in the previous process, in preparation for the reinforcement work to be carried out in the next process, taking into account the scope of the reinforcement work and the route for transporting materials.

[0073] (Reinforcement process) Next, in this construction, a reinforcement process is carried out as part of the temporary cofferdam construction method in the culvert according to this embodiment, as shown in Fig. 17. Fig. 17 is a process explanatory diagram showing the reinforcement process of the temporary cofferdam construction method in the culvert according to this embodiment.

[0074] In this reinforcement process, grooves are formed by cutting inside the concrete skeleton of the central culvert wall 11, reinforcing steel bars are embedded in the formed grooves, and epoxy resin is filled in to fix them in place. After that, reinforcing steel ties are placed on the surface of the skeleton and wrapped around with polymer cement mortar, thereby performing earthquake reinforcement for the central culvert wall 11. By embedding and fixing the reinforcing steel bars inside the concrete skeleton, the reinforcing material is integrated with the existing structure, thereby improving the bearing capacity of the central culvert wall 11, which is an existing structure.

[0075] However, if there are any defects such as damage caused by alkali-silica reaction (ASR) or salt damage, resulting in significant damage to the cover concrete, insufficient concrete strength, small net cover of reinforcing bars, or water entering the structure from outside causing deformation inside the structure, thorough investigation and measures must be taken before construction begins.

[0076] (Scaffolding removal process inside the cofferdam) Next, as shown in Fig. 18, in this work, as part of the temporary cofferdam construction method inside a culvert according to this embodiment, a scaffolding removal process inside the cofferdam is carried out to remove the temporary scaffolding inside the cofferdam that has become unnecessary in the previous process. Fig. 18 is a process explanatory diagram showing the scaffolding removal process inside the cofferdam in the temporary cofferdam construction method inside a culvert according to this embodiment.

[0077] (Water injection into the cofferdam and installation of guide materials) Next, as shown in Figure 19, in this work, as part of the temporary cofferdam construction method in a culvert according to this embodiment, a process of injecting water into the temporary cofferdam and installing guide materials is carried out, in which water is injected into the temporary cofferdam after reinforcement work has been completed from outside the cofferdam using a submersible pump, and guide materials 6 are installed to replace the struts 8b. Figure 19 is a process explanatory diagram showing the process of injecting water into the temporary cofferdam and installing guide materials in the temporary cofferdam construction method in a culvert according to this embodiment.

[0078] (Temporary cofferdam water top removal process) Next, as shown in Figure 20, in this construction, as part of the temporary cofferdam construction method in a culvert according to this embodiment, a temporary cofferdam water-top removal process is carried out to remove the water-top portion of the temporary cofferdam panel material 7, which is the opposite of the temporary cofferdam water-top construction process described above. Figure 20 is a process explanatory diagram showing the temporary cofferdam water-top removal process in the temporary cofferdam construction method in a culvert according to this embodiment.

[0079] (Temporary cofferdam underwater section removal process) Next, as shown in Figure 21, in this work, as part of the temporary cofferdam construction method in a culvert according to this embodiment, a temporary cofferdam underwater portion removal process is carried out, in which the underwater portion of the temporary cofferdam panel material 7 is pulled out and removed in the reverse order of the temporary cofferdam assembly lowering process described above. Note that the edge of the panel material 7 is cut off from the waterproof concrete in advance. Figure 21 is a process explanatory diagram showing the temporary cofferdam underwater portion removal process in the temporary cofferdam construction method in a culvert according to this embodiment.

[0080] Specifically, after removing the scaffolding and struts 8b inside the cofferdam, the panel is pulled out using a jack. In addition, before pouring water into the cofferdam, a pull-out support is installed, and the jack is fixed to the top of the pull-out support with a bullman or similar. Water is then poured into the cofferdam up to just below the struts 8b, and the struts 8b are removed from the lower level to the upper level. The hydraulic unit is installed outside the water distribution channel 10, and hydraulic hoses are piped to the jack. Retaining members are attached to the jack, and pressure is gradually applied (for example, 5 tons per unit) using the water-stopping concrete as a reaction force, and the underwater portion of the cofferdam panel material 7 is pulled out and removed.

[0081] After all of the temporary cofferdam panel material 7 has been pulled out, the support pillar is lifted up with a chain block CB and pulled out and removed. In addition, the connecting bolts of the pulling support pillar are removed underwater by a diver, and then lifted up with a chain block CB and removed.

[0082] (Temporary cofferdam guide material removal process) Next, as shown in Figure 22, in this work, as part of the temporary cofferdam construction method in a culvert according to this embodiment, after all of the temporary cofferdam panel materials 7 are removed, a temporary cofferdam guide material removal process is carried out in which the aforementioned temporary cofferdam guide materials 6 are removed. Basically, the waterproof concrete is left in place and covered with soil and sand from the water distribution channel 10. Of course, the waterproof concrete may be removed. Figure 22 is a process explanatory diagram showing the temporary cofferdam guide material removal process in the temporary cofferdam construction method in a culvert according to this embodiment.

[0083] (Scaffolding installation process) Next, as shown in Figure 23, in this work, as part of the temporary cofferdam construction method inside a culvert according to this embodiment, an overhang scaffolding installation process is carried out to install overhang scaffolding 5a which will serve as suspended scaffolding 5 for removing the traveling rails. Figure 23 is a process explanatory diagram showing the overhang scaffolding installation process of the temporary cofferdam construction method inside a culvert according to this embodiment.

[0084] (Overhead crane removal process) Next, as shown in Figure 24, in this work, as part of the temporary cofferdam construction method for inside a culvert according to this embodiment, an overhead traveling crane removal process is carried out to remove the rails R1 for the overhead traveling crane and the trolley-type manual or electric chain hoist CB, which is the overhead traveling crane, from the underside (ceiling surface) of the top slab 12. Figure 24 is a process explanatory diagram showing the overhead traveling crane removal process of the temporary cofferdam construction method for inside a culvert according to this embodiment.

[0085] (Hanging scaffolding and bracket scaffolding removal process) Next, as shown in Figure 25, in this work, as part of the temporary cofferdam construction method inside a culvert according to this embodiment, a hanging scaffolding and bracket scaffolding removal process is carried out in which the hanging scaffolding 5, including the bracket scaffolding 4 and overhang scaffolding 5a installed directly below the loading / unloading entrance 2, is removed and carried out through the loading / unloading entrance 2. Figure 25 is a process explanatory diagram showing the hanging scaffolding and bracket scaffolding removal process of the temporary cofferdam construction method inside a culvert according to this embodiment.

[0086] After that, as shown in Figure 2, the opening restoration process is carried out to close and restore the opening that was set up as the loading / unloading entrance 2 in the top plate opening process, and the main construction work is completed by restoring the work carried out in the temporary processes mentioned above, namely the work yard preparation process, permanent belt installation process, earthwork process (excavation work and retaining wall work), and the process of installing lighting equipment inside the culvert.

[0087] According to the temporary cofferdam construction method for a culvert according to the present embodiment described above, temporary cofferdam can be reliably performed and construction of a concrete structure in a culvert where water level is always present can be carried out in a dry environment, so that construction can be carried out efficiently in a short time at low cost.

[0088] Furthermore, according to the temporary cofferdam construction method in the culvert according to this embodiment, the panel material is pressed in with a hydraulic jack by utilizing the reaction force from the top plate, so even if the bottom ends of the assembled temporary cofferdam panel materials do not descend under their own weight after hitting the ground inside the culvert, temporary cofferdam can be reliably performed and a dry area can be constructed.

[0089] According to the temporary cofferdam construction method in the culvert of this embodiment, the temporary cofferdam assembly and lowering process is carried out by lowering the suspended scaffolding, so the scaffolding can be brought close to the water surface, making the temporary cofferdam assembly work easier and allowing the temporary cofferdam assembly work to be carried out efficiently in a short time.

[0090] According to the temporary cofferdam construction method in the culvert of this embodiment, a guide material for the temporary cofferdam is installed to guide the direction in which the panel material is lowered or pressed in, so that the work of lowering or pressing in the temporary cofferdam can be carried out accurately, and these works can be carried out efficiently in a short time.

[0091] Furthermore, according to the temporary cofferdam construction method in the culvert according to this embodiment, waterproof concrete is poured, so that the water at the bottom end of the temporary cofferdam can be completely sealed off, and the drainage work can be carried out in a short time to create a dry area.

[0092] According to the cofferdam construction method in the culvert according to this embodiment, the soil inside the cofferdam is dredged and removed outside the cofferdam, so that the soil can be easily removed from the dry area to be constructed in a short time, and the work efficiency of the subsequent process can be improved.

[0093] The temporary cofferdam construction method in an underdrain according to the embodiment of the present invention has been described in detail above. However, the above-mentioned and illustrated embodiments are merely specific embodiments for carrying out the present invention. Therefore, the technical scope of the present invention should not be interpreted as being limited by these embodiments. [Explanation of symbols]

[0094] 10:Diversion waterway 11: Central culvert wall 12:Top version 13: Bottom plate 14: Diversion channel left quay 15: Diversion channel right quay 2: Loading / unloading entrance (opening) 2a: Wire saw guide hole 3: Manhole 3a: Core hole 3b: Hanging jig 4: Bracket scaffolding 4a: Vertical member 4b: diagonal 4c: Horizontal material 5: Suspended scaffolding 5a: Overhanging scaffolding 6: Guide material 7: Panel material 8a: Belly rising 8b: Strand beam

Claims

1. This is a temporary cofferdam construction method in a culvert, which is a concrete structure that is always at water level, and when carrying out underwater construction work in the culvert, it closes off the water with a temporary cofferdam and drains it to create a dry area. a top plate opening step of forming an opening in the top plate of the concrete structure which is a culvert to serve as an entrance / exit for carrying in and out of materials and equipment; a bracket scaffolding installation process for installing a bracket scaffolding below the loading / unloading entrance; a temporary cofferdam assembly lowering process in which temporary cofferdam panel materials are assembled on the bracket scaffolding, and the assembled panel materials are lowered by their own weight, and this process is repeated until they reach the ground inside the culvert; Equipped with a drainage process for draining water from the cofferdam using a submersible pump. This is a temporary cofferdam construction method inside a culvert that is characterized by the following.

2. After the panel material of the temporary cofferdam has landed on the ground, a temporary cofferdam press-in process is carried out in which the panel material is pressed in by a hydraulic jack using the reaction force from the top plate.

2. The temporary cofferdam construction method in a culvert according to claim 1,

3. A suspended scaffolding installation process for installing a suspended scaffolding at a predetermined height from the underside of the top plate; An overhead traveling crane installation process is provided in which a trolley-type manual or electric chain block that can travel on rails as an overhead traveling crane is installed using the suspended scaffolding.

2. The temporary cofferdam construction method in a culvert according to claim 1,

4. After the overhead traveling crane installation process, the suspended scaffolding is lowered to perform the temporary cofferdam assembly lowering process.

4. The temporary cofferdam construction method in a culvert according to claim 3,

5. The temporary cofferdam guide material installation process includes installing a temporary cofferdam guide material that guides the downward or press-in direction of the panel material.

3. A temporary cofferdam construction method in a culvert according to claim 1 or 2, characterized in that:

6. A waterproof concrete pouring step is included in which concrete is poured at the bottom end of the panel material to stop water.

3. A temporary cofferdam construction method in a culvert according to claim 1 or 2, characterized in that:

7. The method includes a dredging process in which sediment in the cofferdam is dredged and discharged outside the cofferdam.

3. A temporary cofferdam construction method in a culvert according to claim 1 or 2, characterized in that:

8. In the top plate opening step, a core drilling machine is used to drill a plurality of core holes through which wire saws are inserted at predetermined positions of the top plate, and the openings are cut using the wire saws inserted into the core holes.

2. The temporary cofferdam construction method in a culvert according to claim 1,

9. In the top plate opening step, the opening is formed by drilling a series of core holes in the top plate using a core drilling machine.

2. The temporary cofferdam construction method in a culvert according to claim 1,

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