JP2015055131A - Cure method of concrete bridge girder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cure method of a concrete bridge girder applicable even to a side surface and an under surface of the concrete bridge girder integrally constructed with cast-in-place concrete.SOLUTION: The outside of the bridge girder 1 is covered by providing a covering surface in a position of respectively separating a proper distance from both left-right side surfaces and a bottom surface of the bridge girder 1, by using a work scaffold installed in a construction site of a bridge. A water supply pipe 81 with a water sprinkling nozzle 83 is arranged inside an area covered with its covering surface, and the area inside is maintained in a wet state by spraying water into the area from the water sprinkling nozzle 83, and concrete after die-removal is cured thereby. In a cantilever overhang construction method for extending by successively joint-connecting the bridge girder 1 from a constructed bridge body in a construction block unit, while moving the covering surface in a bridge axial direction together with the work scaffold 4, the concrete after die-removal is cured in the construction block unit.

Description

  The present invention relates to a method for curing a concrete bridge girder that is erected by concrete cast-in-place (on-site cast).

  As a general construction method for erection of concrete bridges, an appropriate support work is assembled on the supporting ground at the construction site and a work scaffold is installed, and the reinforcement structure and formwork of the bridge girder are constructed using the support work. A cast-in-place support construction method in which concrete is placed in the formwork to construct a bridge girder is representative.

  In addition, in bridges straddling rivers and valleys, it is impossible to assemble a fixed support underneath, so a pier or abutment is constructed first, and the length from the pier or abutment to the bridge axis is about several meters long. A cantilever extension method is often used in which the bridge girder is extended so as to sequentially extend in units of construction blocks (for example, Patent Documents 1 and 2).

  In the conventional general cantilever extension method, as shown in FIG. 15, an erection work vehicle 21 called “wagen” is installed on the constructed pier 11 or the top of the abutment. The construction work vehicle 21 can be moved in the bridge axis direction along the rail 3 fixed on the bridge surface 12. From this construction work vehicle 21, the formwork 5 and the work scaffold 4 of the construction block adjacent to the pier or the abutment are suspended. After assembling the reinforcing bar structure of the construction block using the work scaffold and connecting the sheath of the PC steel material, the concrete is placed in the formwork to construct the bridge girder of the construction block.

  When the cast concrete reaches a strength sufficient to remove the formwork, the formwork 5 is removed, the construction work vehicle 21 is advanced along the rail 3, and the formwork 5 is moved to the position of the next construction block. Similarly, the bridge girder of the next construction block is constructed, and this process is repeated to extend the bridge girder. In order to balance the moment, the pier 11 or both sides of the abutment is usually constructed in parallel.

  By the way, in a building constructed in this way by concrete cast-in, the curing of the concrete during the construction period greatly affects the construction quality. When concrete shrinks rapidly by drying, cracking occurs and strength and durability are impaired. To prevent this, it is required to maintain the concrete in a proper wet state for a certain period of time.

  In an outdoor high place environment where bridges are built, concrete under construction is constantly exposed to strong sunlight and strong winds, so drying of the concrete is much faster. Under such circumstances, in conventional concrete bridge construction, a mat for wet curing is laid on the surface of the concrete floor slab constituting the bridge surface (Patent Document 3), or the floor slab surface is covered with a roof and side walls. A curing method such as spraying water (Patent Document 4) is employed.

JP-A-6-185018 JP 11-256521 A JP 2009-30246 A JP 2004-162375 A

  The concrete bridge girder includes a box girder bridge 91 having a rectangular hollow cross section as shown in FIG. 16 (a), a hollow floor slab bridge 92 having a circular hollow cross section as shown in FIG. A plate girder bridge 93 or the like that supports the upper floor plate by a plurality of T-shaped beams as shown in c) is often employed. In these concrete bridge girders, the entire cross section of the bridge girder is integrally formed of concrete.

  However, only the surface of the upper floor slab (upper flange) 94 can maintain the concrete placement site in a wet state by the conventional curing method. In order to cure the underside of the overhanging floor slab 95 or the bottom floor slab (lower flange) 96, the left and right side walls (webs) 97 of the box girder bridge 91, the main girder 98 of the slab girder bridge, etc. However, it is very difficult to assemble, disassemble and move them at high altitudes outdoors. Therefore, the actual situation is that a method for efficiently curing the side portion and the bottom portion of this type of concrete bridge girder has not yet been put into practical use.

  This invention is made | formed in view of such a situation, and provides the curing method applicable also to the side surface, lower surface, etc. of a bridge girder especially constructed by cast-in-place concrete.

  In order to achieve the above-mentioned object, the concrete bridge girder curing method of the present invention is to install a work scaffolding via an appropriate support work at the construction site of the bridge, and to use the work scaffolding to reinforce the bridge girder reinforcement structure and In the construction work of a concrete bridge for assembling a formwork and placing concrete in the formwork to construct a bridge girder, using the work scaffolds installed on the sides and below the bridge girder, both left and right sides of the bridge girder A covering surface is provided at an appropriate distance from the bottom surface to cover the outside of the bridge girder, and a water supply pipe with a watering nozzle is disposed inside the region covered by the covering surface, and the watering nozzle Then, water is sprayed into the region to maintain the region in a wet state, thereby curing the concrete after demolding. In this way, the side and bottom surfaces of the bridge girder are preferably formed by covering the side and lower side of the bridge girder using the work scaffold for constructing the bridge girder and spraying water on the inside to maintain the wet state. Can be cured.

  Further, according to the method for curing a concrete bridge girder of the present invention, on the constructed bridge body (pier pier, abutment or bridge girder), a scaffold suspension means movable in the direction of the bridge axis is installed, and the scaffold suspension means is used. While suspending the formwork and work platform on the front end side of the built bridge body, the reinforcing bar structure and formwork are assembled in units of construction blocks of a predetermined length, and concrete is placed in the formwork, and the bridge girder is assembled. In the construction work of concrete bridges that extend in the direction of the bridge axis in order, using the above work scaffolds, at appropriate distances from the left and right side surfaces, the front end surface, and the bottom surface of the bridge girder in the current construction block A covering surface is provided to cover the outside of the bridge girder, and a water supply pipe with a watering nozzle is disposed inside the region covered with the covering surface, and water is sprayed from the watering nozzle into the region. In the region By maintaining the wet state, the concrete after demolding in the block currently under construction is cured, and the curing process is performed in units of construction blocks while moving the covering surface and the water supply pipe along with the work scaffold in the direction of the bridge axis. The configuration is repeated. According to this configuration, particularly when the cantilever overhanging method is employed, the side surface and the bottom surface of the bridge girder can be suitably cured in units of construction blocks.

  In each of the above-mentioned configurations, the work scaffold is constructed by assembling a work floor formed by laying a scaffold cloth board substantially horizontally without a gap, and a portal steel pipe building frame on the work floor to an appropriate height. It is assumed that the frame scaffold is formed, and for the covering surface, the work floor, and a covering sheet stretched so as to face the bridge girder along the vertical and horizontal frame members constituting the frame scaffold, Are preferably constituted by being continuously integrated. In this way, if the work floor is configured to also serve as a part of the covering surface, the bridge girder can be efficiently covered only by stretching the covering sheet in the vertical direction.

  As a specific configuration of the covering sheet in each of the above-described configurations, a plurality of unit sheets formed in an oblong shape having a predetermined size are joined together, and a fastener is attached to the edge of each unit sheet. Are attached, and the edge portions of the adjacent unit sheets are joined to each other via the fasteners, and the corner portions of the unit sheets are provided with engaging means for the vertical and horizontal frame members constituting the previous frame frame scaffolding. It is preferred that By adopting this configuration, the covering sheet can be easily stretched in various directions in various directions.

  When covering the bridge girder with the covering sheet, the bridge surface of the bridge girder is covered with a curing sheet, and the upper edge portion of the covering sheet stretched so as to face both the left and right side surfaces of the bridge girder is on the bridge surface. By extending to the left and right edges of the curing sheet, the range from the bridge surface to the left and right side surfaces of the bridge girder may be integrally covered.

  In addition, especially about the covering surface in the case of adopting the cantilever extension method, it may be configured to cover only the block currently under construction (the construction block in a state where the concrete is cast and removed). However, the work scaffold is installed so as to cover at least the range from the block currently being constructed to the next construction block, and the covering surface is also integrated with at least the range from the block currently being constructed to the next construction block. You may provide so that it may coat | cover.

  When this structure is adopted, when the bridge girder is a box girder having a hollow portion having a substantially rectangular cross section, the region covered by the covering surface is integrally communicated from the outside of the bridge girder to the hollow portion. It is also possible to collectively manage the humidity in the area.

  In particular, when adopting the cantilever extension method, a tank and a pump device for supplying water to the water supply pipe are installed on the constructed bridge body, and the tank and the pump device are By moving the construction surface unit along the covering surface and the work scaffold in the direction of the bridge axis, or by extending the hose connected to the pump device without moving the pump device, the concrete after demolding Curing work can be efficiently repeated for each construction block.

  According to the curing method of the concrete bridge of the present invention configured as described above, the underside of the overhanging slab, bottom floor slab, left and right side walls and main girder of a box girder bridge, hollow floor slab bridge, slab girder bridge, etc. As for the side surfaces and the like, the demolding surface can be kept moist for a certain period of time, and the concrete can be properly cured. This curing dramatically improves the construction quality of cast-in-place concrete bridges that are exposed to strong sunlight and strong winds.

  In addition, the method for curing a concrete bridge according to the present invention is configured to stretch a covering sheet using a conventional general work scaffolding and supporting work necessary for constructing a bridge body. The process can be carried out without adding a large amount of materials and equipment or changing the process, simply by adding a process of stretching a covering sheet and disposing a water supply pipe. Therefore, the construction is safe and inexpensive, and it can be flexibly applied not only to the fixed support method, but also to a cantilever extension method or a similar method using a frame scaffold.

It is a top view (AA arrow view in FIG. 3, FIG. 6 but the construction work vehicle above a bridge girder is displayed with an imaginary line) which shows the construction form of the bridge girder by a cantilever extension method. It is a cross-sectional view (BB arrow line view in FIG. 3, FIG. 6) of the said bridge girder. It is a bridge-axis direction longitudinal cross-sectional view (CC arrow view in FIG. 1, FIG. 6) of the said bridge girder. FIG. 7 is a longitudinal cross-sectional view of the bridge girder in the direction of the bridge axis (a DD arrow view in FIGS. 1 and 6). It is a longitudinal cross-sectional view (the EE arrow view in FIG. 1, FIG. 6) of the bridge axial direction of the said bridge girder. It is a longitudinal cross-sectional view (the FF arrow line view in FIG. 1, FIG. 3) of the bridge width direction of the said bridge girder. It is a longitudinal cross-sectional view (GG view in FIG. 1, FIG. 3) of the bridge width direction of the said bridge girder. It is a figure which shows the construction form which advanced one construction block from FIG. FIG. 3 is a diagram in which a covering sheet extending position and a water supply pipe arrangement position are added to FIG. 2 as the first embodiment of the present invention. Similarly, it is the figure which added the extending position of a coating sheet, and the arrangement position of a water supply pipe to FIG. Similarly, it is the figure which added the extending position of a coating sheet, and the arrangement position of a water supply pipe to FIG. As a second embodiment of the present invention, FIG. 2 is a diagram in which a covering sheet extending position and a water supply pipe disposing position are added to FIG. 2. Similarly, it is the figure which added the extending position of a coating sheet, and the arrangement position of a water supply pipe to FIG. Similarly, it is the figure which added the extending position of a coating sheet, and the arrangement position of a water supply pipe to FIG. It is a schematic side view showing an outline of a conventional general cantilever overhanging method. It is sectional drawing of a general concrete bridge girder, (a) is a box girder bridge, (b) is a hollow floor slab bridge, (c) is sectional drawing of the bridge width direction of a slab girder bridge.

  First, construction work of a concrete bridge girder to which the present invention is applied will be described with reference to the drawings.

  1-7 has illustrated the general construction form of the concrete bridge girder 1 by the cantilever extension method demonstrated also in the background art column. In this construction method, a scaffold suspension means 2 that can move in the direction of the bridge axis is installed on a bridge body (bridge pier 11, abutment or bridge girder) that has already been constructed. Using this scaffold suspending means 2, the work scaffold 4 and the formwork 5 are suspended in front of the constructed bridge body, and the reinforcing bar structure is constructed in units of construction blocks of a predetermined length (approximately 3 to 4 m) (see FIG. (Not shown) and the mold 5 are assembled, and concrete is placed in the mold 5. In addition, in this specification, the front end side (the right side in FIGS. 1 to 5) in the extending direction of the bridge girder 1 is “front”, and the constructed bridge body side is “rear”, and the positional relationship of each part and member explain.

  When the concrete placed in the formwork 5 reaches the strength at which the formwork can be removed, the formwork 5 is removed, the scaffold suspension means 2 is advanced along the bridge axis direction, and the formwork 5 is moved to the next construction block. Move to the position of, and build the bridge girder of the next construction block in the same procedure. Usually, in order to balance the moment, the bridge girder 1 is extended by repeating this process while constructing both sides of the pier 11 or the abutment simultaneously in parallel.

  The illustrated bridge girder 1 is designed such that the bridge surface 12 is slightly inclined in both the bridge axis direction and the bridge width direction (direction orthogonal to the bridge axis direction). The inclination angle of the surface 12 is not particularly limited.

[Mechanical suspension suspension]
As the scaffold suspension means 2 used in the cantilever extension method, an erection work vehicle (wagen) 21 made of a steel truss structure and a rail that supports the erection work vehicle 21 so as to be movable in the direction of the bridge axis. In general, a combination of 31 and 31 is used.

  The construction work vehicle 21 includes a plurality of rows (two rows on the left and right in the illustrated embodiment) main structures (main frames) 22 arranged in parallel with each other. Each main structure 22 has a truss structure surface having a substantially parallelogram shape in a side view, the truss structure surface is directed in the direction of the bridge axis, and the front end side of the truss structure surface is projected forward of the constructed bridge body. Thus, it is installed on the constructed bridge body (see FIG. 3).

  The left and right main structures 22 are connected to each other in the bridge width direction via a pair of front and rear suspension horizontal beams 23 and 24 that are bridged horizontally on top of them. These suspension horizontal beams 23 and 24 are formed by combining sections of steel having a large cross section, and both ends of the cross beams extend larger than the width of the bridge girder 1. Most of the various temporary materials including the work scaffold 4 are suspended by these front and rear suspension transverse beams 23 and 24. An upper work scaffold 25 for hanging various temporary materials and the like is provided on the upper part of the main structure 22 connected by the horizontal beams 23 and 24, and a roof 26 is installed above the work scaffold 25. Yes. Further, an auxiliary work scaffold 27 including a suspension beam is provided below the front end of the main structure 22.

  The lower part of the main structure 22 is fixed to a built bridge body via an anchor member 28 while being supported on a plurality of rows of rails 31 (two rows on the left and right in the illustrated embodiment) arranged along the bridge axis direction. Is done. A main jack 29 for adjusting the installation posture of the main structure 22 is installed at the lower front end of each main structure 22.

  The rail 31 is installed on the bridge surface 12 via a plurality of pillow timbers 32 arranged at appropriate intervals, and is fixed to a built bridge body by rail anchors 33. The lower front end and the lower rear end of the main structure 22 are engaged with each other by rail engaging members 34 and 35 each having a roller. Further, a drive device 36 for moving the main structure 22 and the rail 31 forward and backward relatively is installed at the front portion of the main structure 22.

  As a result, the main structure 22 can be moved in the direction of the bridge axis along the rail 31 with the rail 31 fixed to the bridge body, and the rail anchor 33 can be mounted with the main structure 22 fixed to the bridge body. It is also possible to cancel and move only the rail 31 in the direction of the bridge axis.

[Working scaffold]
The work scaffold 4 for constructing the bridge girder 1 includes a pair of front and rear scaffold receiving beams 41 and 42 suspended from the main structure 22, and a plurality of scaffold girders 43 spanned on the scaffold receiving beams 41 and 42, The scaffolding cloth 44 laid on the scaffolding girder 43, the frame scaffolding 45 assembled on the scaffolding cloth board 44, and the like (see FIGS. 3 to 6).

  The front and rear scaffold receiving beams 41 and 42 are formed by combining large cross-sectional steel members in the same manner as the suspension horizontal beams 23 and 24 installed on the main structure 22, and both ends of the front and rear suspension horizontal beams 23 and 24. From the vicinity, using a Gevin de Stap (fully threaded steel rod) 46 and a suspension pillar 47 made of a steel shape material in combination, directly below each suspension horizontal beam 23, 24, and with the front and rear heights aligned horizontally Suspended.

  The scaffolding girder 43 is bridged on the scaffolding receiving beams 41, 42 at appropriate intervals so as to be orthogonal to the front and rear scaffolding receiving beams 41, 42, and the front and rear ends thereof are respectively forward and backward of the scaffolding receiving beams 41, 42, respectively. Is overhanging.

  The scaffold cloth plate 44 is made of, for example, a wooden plate material, a thin steel plate, or the like, and is laid on the scaffold girder 43 substantially horizontally with almost no gap. The laying surface of the scaffold cloth plate 44 serves as a work floor. Normally, concrete is placed on the block currently being constructed and the next construction block rebar is assembled within a few days waiting for its hardening, so the work floor must be at least 2 to allow the work to be done. It is installed to cover a range of blocks (preferably 3 blocks) or more.

  The frame scaffolding 45 is formed by stacking a certain number of steel pipe building frames welded to a gate shape in combination with jack bases, cross braces, steel cloth boards and baseboards, staircase frames, handrails, etc. It is a scaffold. In the illustrated embodiment, the scaffolding plate 44 is fixed to the scaffolding large pull made of a square steel pipe and the jack member having the groove-shaped receiving member is faced downward to be fitted into the scaffolding large pulling. 45 feet are stabilized.

  The frame scaffold 45 is assembled to a predetermined height so as to face both the left and right side surfaces and the front end surface of the bridge girder 1. The building frame located on the outermost side of the frame scaffolding 45 is raised to the upper side of the upper floor slab of the bridge girder 1 in a state of being attached to the suspension column 47, and a protective net 48 is stretched on the outer side surface thereof. Is done. Further, an upper work floor 49 facing the lower surface of the overhanging portion of the upper floor slab of the bridge girder 1 is installed at the upper part of the inner part of the frame scaffold 45.

[Formwork]
The formwork 5 for the bridge girder 1 (box girder) having a hollow portion 13 having a substantially rectangular cross section is an outer formwork for forming the outer side surface of the side wall 14, the overhanging portion 15 of the upper floor slab and the bottom surface of the bottom floor slab 16. 51 and an inner mold 52 for forming the inner surface of the side wall 14 and the bottom surface of the central portion 17 of the upper floor slab (see FIG. 6). Both the outer mold 51 and the inner mold 52 are formed by connecting a plurality of metal foams (steel plate panels) of a predetermined size.

  The outer mold frame 51 is supported by a pair of front and rear outer frame receiving beams 53 and 54 suspended from a pair of front and rear suspension horizontal beams 23 and 24 installed on the main structure 22. The outer formwork receiving beams 53 and 54 can be lifted and lowered independently from the work scaffold 4 to a position slightly higher than the work scaffold 4 via the chains 55 and the like from the respective transverse beams 23 and 24 for suspension. Suspended. The front and rear outer formwork receiving beams 53 and 54 are held so as to have different heights in the front and rear in accordance with the inclination angle of the bottom surface of the bridge girder 1 and are also inclined at a predetermined angle in the bridge width direction. The rear outer frame receiving beam 54 is suspended from the vicinity of both ends of the rear suspension horizontal beam 24 so as to straddle the width of the bridge girder 1, so that it is slightly longer than the entire width of the bridge girder 1. Although the member is used, the front outer frame receiving beam 53 is suspended at a position ahead of the next construction block, so that a member shorter than the rear outer frame receiving beam 54 is used. ing. A plurality of outer formwork support girders 56 are bridged in the bridge axis direction at appropriate intervals on the front and rear outer formwork receiving beams 53 and 54, and the bottom of the outer formwork 51 is placed thereon. And held at a predetermined height.

  As for the inner mold 52, the side wall portion is connected to the opposite side wall portion of the outer mold frame 51 via a separator (not shown) so as to maintain a predetermined interval, and an appropriate mold frame is formed from the outside of both. They are fixed to each other using a support (not shown). Further, the center portion 17 of the upper floor slab is supported by a plurality of (three in the illustrated embodiment) inner frame support girders 57 suspended in the hollow portion 13 of the box girder. The inner form frame support girder 57 is hung in the vicinity of the front end of the inner frame support girder 57 via the chain 55 and the like from the front side horizontal beam 23 installed on the main structure 22, while the rear end of the inner form frame support girder 57 is already constructed. It is suspended below the upper floor slab by an anchor member 58 (see FIG. 3) attached so as to penetrate the upper floor slab, and is held so as to incline in the bridge axis direction according to the inclination angle of the upper floor slab.

  The mold 58 (see FIG. 2) for forming the front end face (joint surface) of each construction block is also made of a metal foam having a predetermined shape, and is fixed as described above and the outer mold 51 and the inner mold. The frame 52 is connected to each other. In addition, since the separator 58 cannot be used for the mold 58 on the front end face, there is a case where the formwork 58 is supported by taking a single tube from the work scaffold 4.

[Reinforcing bar structure]
The reinforcing bar structure constituting the bridge girder 1 is not shown in the figure, but has been constructed in parallel with the building work of the formwork 5 for each appropriate part such as the upper floor slabs 15, 17, both side walls 14, and the bottom floor slab 16. While being sequentially coupled to the joint portion protruding from the bridge body, the parts are also connected to each other. A sheath (not shown) for inserting a PC steel material that applies prestress to the bridge girder 1 is also connected in the direction of the bridge axis before and after assembly of the reinforcing bar structure.

[Coated surface]
The main part of the present invention is that the outer surface of the bridge girder 1 is covered and the surface after demolding of the concrete is wet-cured. The covering surface covering the outside of the bridge girder 1 is formed by continuously connecting a work floor formed by laying the scaffold cloth plate 44 without gaps and a covering sheet stretched along the frame scaffold 45 without gaps. Consists of. Examples of the form in which the covering sheet 6 is stretched on the work scaffold 4 of the bridge girder 1 by the cantilever extending method shown in FIGS. 1 to 7 are shown in FIGS.

  The covering sheet 6 is made of a flexible sheet material made of a synthetic resin that has been subjected to waterproofing and water resistance treatment, and is formed by joining together a plurality of unit sheets formed in a long rectangle or other appropriate shape with a predetermined dimension. The At the corners and intermediate portions of each unit sheet, for example, eyelet-shaped hardware, tie cords, wrapping belts (not shown), etc., are used as engaging means for the vertical and horizontal frame members constituting the frame scaffold 45. It is attached. Moreover, a hook-and-loop fastener or a zip fastener (not shown) is attached to the edge of each unit sheet, and the edges of the adjacent unit sheets are joined to each other via the fasteners. Any of these joining parts is formed so that it can be easily opened and closed as an entrance / exit of a field worker.

  In the cantilever extension method, the covering sheet 6 is stretched along the frame material of the frame scaffold 45 so as to surround at least the left and right side surfaces and the front end surface of the bridge girder 1 in the block currently being constructed. The The covering sheet 6 stretched so as to face the side surface of the bridge girder 1 is formed by using a curing tape or the like on the side wall 14 of the bridge girder 1 whose rear edge portion (the edge portion on the constructed bridge body side) has already been sufficiently cured. Temporarily fixed. Further, the lower edge portion of the covering sheet 6 is overlapped on the work floor of the work scaffold 4 and temporarily fixed by an appropriate pressing member or the like. The upper edge portion of the covering sheet 6 extends to the bridge surface 12 along the frame scaffold 45. A curing sheet 7 (see FIG. 11) covering the entire bridge surface 12 is also laid on the bridge surface 12, and the upper edge portion of the covering sheet 6 is overlapped on both edge portions thereof.

[Humidification means]
A water supply pipe 81 (see FIGS. 9 to 14) is disposed inside a region covered by the covering surface (hereinafter referred to as “covering region”) so as to follow the frame scaffold 45 or the like. The water supply pipe 81 is configured by connecting, for example, a straight pipe made of stainless steel pipe or the like and a flexible pipe made of synthetic resin or the like. The water supply pipe 81 is arranged so as to be continuous over a plurality of steps or rows while being routed in the horizontal direction or the vertical direction along the side surface of the bridge girder 1 and folded in the opposite direction in the vicinity of the end of the covering region. Is done. In order to fix the water supply pipe 81 to the frame scaffold 45, for example, a band-like binding member (not shown) made of synthetic resin or metal is used.

  Water is supplied to the water supply pipe 81 via a tank / pump device 82. The tank / pump device 82 is installed on the constructed bridge surface 12. Watering nozzles 83 are attached to the water supply pipe 81 at appropriate intervals, and mist-like water is sprayed from the watering nozzles 83 into the air in the covering region. As the specification of the watering nozzle 83, it is practical to spray about several tens of cc of water per minute with a particle diameter of about several μm to several tens of μm at a discharge pressure of about several MPa. By this water spraying, the inside of the coated area is maintained in a high humidity state (approximately 90% as a guideline) until the concrete after demolding exhibits a predetermined strength (1 to 4 weeks as a guideline). The water spray may be performed continuously at all times, or may be performed intermittently using, for example, timer control of the tank / pump device 82 or temperature / humidity sensor control in the covering region.

[Tensioning form of covering sheet]
Two types of examples are shown below regarding the form of covering sheet 6 on work scaffold 4 of bridge girder 1 by the cantilever overhang method shown in FIGS. While explaining.

(First embodiment)
FIGS. 9-11 shows 1st Embodiment regarding the extending | stretching form of the coating sheet 6. FIG.

  The bridge girder 1 in the illustrated embodiment is in a state where the concrete placement is finished in the construction block 101 adjacent to the head of the pier 11 and the demolded concrete is further cured for a certain period. This construction block 101 is referred to as “current construction block (nth block: n is a natural number)”.

  The rail 31 that constitutes the scaffold suspension means 2 extends to the front end of the block 101 that is currently being constructed, and is fixed to the block 101 that is currently being constructed. The construction work vehicle 21 is installed so as to project from the front end of the block 101 currently being constructed to the top of the next construction block 102 (n + 1th block) indicated by a one-dot chain line. And the work scaffold 4 is installed so that it may cover the range for about 3 blocks from the block 101 under construction now to the next construction block 102, and also the next construction block (n + 2nd block) which is not illustrated. The next construction block 102 is in a state where the reinforcing bar structure is assembled using the work scaffold 4 and the formwork 5 is being built. Therefore, many of the field workers are performing various operations near the next construction block 102.

  In this construction state, the covering sheet 6 indicated by a thick wavy line in the figure is from the rear end of the block 101 being currently constructed (the connection portion with the head of the pier 11) to the front end (next) of the block 101 being currently constructed. It is stretched so as to cover the range up to the connection block with the construction block 102). Specifically, on the side of the side walls 14 of the bridge girder 1 in the block 101 under construction, from the work floor of the work scaffold 4 to the height near the upper work floor 49 provided below the overhanging portion 15 of the upper floor slab, A covering sheet 6 (61) on the side face of the bridge girder is stretched in the vertical direction. Between the covering sheet 6 (61) and the side wall 14 of the bridge girder 1, an interval (approximately several tens of cm to 2 m) is provided so that field workers can come and go.

  The covering sheet 6 (62) on the rear end face is connected to the rear end of the covering sheet 6 (61) on the side face of the bridge girder so as to be orthogonal to the side wall 14 of the bridge girder 1. The edge of the covering sheet 6 (62) on the rear end face is temporarily fixed to the side wall 14 of the bridge girder 1. On the other hand, the front end face covering sheet 6 (63) is stretched at the front end of the covering sheet 6 (61) on the side face of the bridge girder so as to be orthogonal to the side wall 14 of the bridge girder 1. The edge portion of the front end face covering sheet 6 (63) is bent along the side wall 14 of the bridge girder 1 and temporarily fixed to the side wall 14 of the bridge girder 1.

  A cover sheet 6 (64) extending further upward is connected to the upper edge of the cover sheet 6 (61) on the side surface of the bridge girder, and this cover sheet 6 (64) is connected to the overhanging portion 15 of the upper floor slab of the bridge girder 1. Besieged. On the upper edge portion of the covering sheet 6 (64), the edge portion of the curing sheet 7 laid on the bridge surface 12 is overlapped and temporarily fixed to each other.

  Moreover, about the inside of the hollow part 13 of the bridge girder 1, covering the whole cross section of the width direction of the hollow part 13 in the position of the rear end and front end of the block 101 under construction now, respectively, the covering sheet 6 (65), 6 (66) is stretched. The peripheral portions of the respective covering sheets 6 (65) and 6 (66) are temporarily fixed to the inner peripheral surface of the hollow portion 13.

  A water supply pipe 81 with a watering nozzle 83 is disposed inside the covering region thus configured. In the illustrated embodiment, in the side space of the both side walls 14 of the bridge girder 1, one system of water supply pipes 81 is routed in the lateral direction, folded back in the vicinity of the end of the covering region, and continuously extended over three levels. It is arranged to do. In the water supply pipe 81, three water spray nozzles 83 are attached to each stage with the spray holes directed toward the side wall 14.

  Further, in the hollow portion 13 of the bridge girder 1, a water supply pipe 81 (not shown) is inserted into the hollow portion 13 from the bridge surface 12 through a small hole (not shown) formed through the central portion 17 of the upper floor slab of the bridge girder 1. Z) is inserted. A watering nozzle is also attached to the tip of the water supply pipe 81.

  And by spraying water from these watering nozzles 83, the side space of the both side walls 14 of the bridge girder 1 and the space in the hollow portion 13 can be maintained in a wet state. This wet curing is continued for about 1 to 4 weeks after the placement of the block 101 during the current construction.

  During this wet curing period, concrete is placed on the next construction block 102. In parallel with or before and after that, preparations for assembling reinforcing bars to successive construction blocks are also made. Then, when the concrete placed in the next construction block 102 exhibits a predetermined strength, the mold 5 is removed, and the work scaffold 4 and the covering sheet 6 are moved forward by one block.

  In this moving work, first, the work scaffold 4 is not moved as it is, and the outer form frame receiving beams 53 and 54 and the internal form support beam 57 suspended from the construction work vehicle 21 are once lowered to form the formwork. 5 is separated from the bridge girder 1. Moreover, all the temporary fix | stop locations of the covering sheet 6 and the block 101 under construction are also removed. If the formwork 5, the working scaffold 4, the covering sheet 6, etc. are separated from the block 101 under construction in this way, the rail anchor 33 on the bridge surface 12 is released and the rail 31 is moved forward by one block. Then, fix the bridge surface 12 again. Next, the anchor member 28 and the like that fix the erection work vehicle 21 are released, the erection work vehicle 21 is moved forward by one block along the rail 31, and then fixed again. By such a procedure, the mold 5 and its supporting member, the work scaffold 4, the covering sheet 6, the water supply pipe 81, etc. can be moved together by one block. The tank / pump device 82 connected to the water supply pipe 81 is also moved forward by one block as the construction work vehicle 21 moves forward.

  When this moving work is completed, the mold 5 is built at the position of the next construction block, and the edge of each covering sheet 6 is covered so as to cover the range from the rear end to the front end of the next construction block 102. Temporarily fix to bridge girder 1. And the concrete after demolding in the next construction block 102 is wet-cured similarly. Such a procedure is repeated one block at a time to construct bridge girder 1.

(Second Embodiment)
12-14 shows 2nd Embodiment regarding the stretched form of the coating sheet 6. FIG.

  As in the first embodiment, the bridge girder 1 in the second embodiment is also subjected to the wet curing of the demolded concrete after the concrete placement is finished in the block 101 under construction that is adjacent to the head of the pier 11. However, in the next construction block 102, the rebar structure is assembled and the formwork 5 is being built. The installation position of the construction work vehicle 21 and the suspended state of the work scaffold 4 are the same as in the first embodiment, and the work scaffold 4 extends from the current work block 101 to the next work block 102 and further to the next work block. It is installed to cover a range of about 3 blocks.

  In the second embodiment, the covering sheet 6 is in a range (more preferably) from the rear end of the block 101 that is currently being constructed (the connection portion with the head of the pier 11) to the front of the next construction block 102. Is stretched so as to cover the range including the next construction block. Specifically, the upper work floor provided on the side of the both side walls 14 of the bridge girder 1 in the current construction block 101 and the next construction block 102 from the work floor of the work scaffold 4 and below the overhanging portion 15 of the upper floor slab. The covering sheet 6 (61) on the side surface of the bridge girder is stretched in the vertical direction up to a height of about 49. Between the covering sheet 6 and the side wall 14 of the bridge girder 1, an interval (generally about several tens of cm to 2 m) is provided so that field workers can come and go.

  Further, the covering sheet 6 (67) on the bridge girder face is provided at a position further forward than the front end of the next construction block 102 from the work floor of the work scaffold 4 to the height near the upper floor slab over the entire width direction of the bridge girder 1. It is stretched. An interval is also provided between the covering sheet 6 (67) and the front end of the next construction block 102 so that a field worker can come and go.

  The left and right edges of the bridge girder face covering sheet 6 (67) are connected to the front ends of the left and right bridge girder side cover sheets 6 (61), respectively, to form a large airtight surface that is integrally continuous. doing. The covering sheet 6 (62) on the rear end face is connected to the rear end of the covering sheet 6 (61) on the side face of the bridge girder so as to be orthogonal to the side wall 14 of the bridge girder 1. The edge of the covering sheet 6 (62) on the rear end face is temporarily fixed to the side wall 14 of the bridge girder 1.

  A cover sheet 6 (64) extending further upward is connected to the upper edge of the cover sheet 6 (61) on the side surface of the bridge girder, and this cover sheet 6 (64) is connected to the overhanging portion 15 of the upper floor slab of the bridge girder 1. Besieged. On the upper edge portion of the covering sheet 6 (64), the edge portion of the curing sheet 7 laid on the bridge surface 12 is overlapped and temporarily fixed to each other.

  Further, a covering sheet 6 (68) extending obliquely upward is also connected to the upper edge of the covering sheet 6 (67) on the bridge girder surface, and this covering sheet 6 (68) is connected to the central portion 17 of the upper floor slab. Is temporarily fixed in the vicinity of the front end of the inner mold 52.

  About the inside of the hollow part 13 of the bridge girder 1, the covering sheet 6 (65) which plugs up the whole cross section of the width direction of the hollow part 13 is stretched only in the position of the rear end of the block 101 under the present construction. The peripheral edge of the covering sheet 6 (65) is temporarily fixed to the inner peripheral surface of the hollow portion 13. That is, in the second embodiment, the space in the hollow portion 13 of the bridge girder 1 communicates with the side spaces of the side walls 14 of the bridge girder 1 integrally.

  A water supply pipe 81 with a watering nozzle 83 is disposed inside the covering region thus configured. In the illustrated embodiment, in the side space of the both side walls 14 of the bridge girder 1, one system of water supply pipes 81 is routed in the lateral direction, folded back in the vicinity of the end of the covering region, and continuously extended over three levels. It is arranged to do. The water supply pipe 81 is provided with five water spray nozzles 83 at each stage with the spray holes directed toward the side wall 14.

  And by spraying water from these watering nozzles 83, the side space of the both side walls 14 of the bridge girder 1 and the space in the hollow portion 13 communicating therewith can be maintained in a wet state. That is, the area covered by the covering sheet 6 and the work floor communicates integrally from the outside of the bridge girder 1 to the inside of the hollow portion 13, so that the humidity management in the space becomes easy. This wet curing is also continued for about one to two weeks after demolding of the block 101 currently under construction.

  During the wet curing period, the concrete for the next construction block 102 is placed. In parallel with or before and after that, preparations for assembling reinforcing bars to successive construction blocks are also made. Then, when the concrete placed in the next construction block 102 exhibits a predetermined strength, the mold 5 is removed, and the work scaffold 4 and the covering sheet 6 are moved forward by one block.

  The procedure of this moving work is basically the same as that in the first embodiment. That is, the work scaffold 4 is not moved as it is, and the outer formwork receiving beams 53 and 54 and the inner formwork support girder 57 suspended from the construction work vehicle 21 are once lowered to separate the formwork 5 from the bridge girder 1. Let Moreover, all the temporary fix | stop locations of the covering sheet 6 and the block 101 under construction are also removed. If the formwork 5, work scaffold 4, covering sheet 6 and the like are separated from the block 101 under construction in this way, the rail 31 on the bridge surface 12 is moved forward by one block and fixed to the bridge surface 12 again. After reworking, the construction work vehicle 21 is moved forward by one block along the rail 31 and is fixed again. By such a procedure, the mold 5 and its supporting member, the work scaffold 4, the covering sheet 6, the water supply pipe 81, the tank, the pump device, and the like can be advanced together by one block.

  When this moving work is completed, the mold 5 is built at the position of the next construction block, and the edge of each covering sheet 6 extends from the rear end of the next construction block 102 to the front of the next construction block. Temporarily fix so as to cover. Then, the concrete after demolding in the next construction block 102 is wet-cured. Such a procedure is repeated one block at a time to construct bridge girder 1.

[Other Embodiments]
So far, the curing method in the case of erection of concrete bridge girders by the cantilever extension method has been described by taking a box girder bridge as an example, but the present invention is a hollow floor slab bridge or slab girder bridge with slightly different cross-sectional shapes. The same applies to.

  In addition, the present invention can be applied not only to the cantilever extension method but also to a cast-in-place support method for supporting a formwork by assembling a support work on a support ground in a section where a bridge is installed. is there. Even in that case, work scaffolds will be installed on the sides and below the bridge girder via support works, and covering surfaces will be provided at appropriate distances from the left and right sides and the bottom of the bridge girder. Cover the outside of the bridge girder. Similar to the embodiment described above, the work floor of the work scaffold is constructed by laying the scaffold cloth board without gaps, assembling the frame scaffold on the work floor, and stretching the covering sheet along the frame scaffold to form the bridge girder. It can coat efficiently. The range in which the covering sheet is stretched is set in accordance with the construction area, that is, the concrete placement range (formation range of the formwork). By arranging a water supply pipe with a watering nozzle inside the coating area, spraying water from the watering nozzle and maintaining the inside of the coating area in a wet state, the concrete after demolding can be suitably cured. it can.

  Whether the concrete bridge girder curing method of the present invention is applied to either the cantilever extension method or the fixed support construction method, the detailed structure of the means for suspending or supporting the scaffold and the details of the work scaffold itself The structure and the like are not particularly limited. In addition, the procedure for stretching the covering sheet using these work scaffolds, the joining form of the covering sheets, the connection between the covering sheet and the bridge girder, how to fit the edge of the covering sheet, the opening / closing part for the entrance / exit The position to be provided, the arrangement of the water supply pipes, the arrangement of the watering nozzles, etc. may be appropriately determined according to the balance between the shape of the construction area and the work scaffold.

DESCRIPTION OF SYMBOLS 1 Bridge girder 11 Bridge pier 12 Bridge surface 13 Hollow part 14 Side wall 15 Overhanging part 16 Upper floor slab 17 Center part 101 of upper slab Next block 102 in present construction Next construction block 2 Scaffolding means 21 Construction work vehicle 22 Main Structure 3 Rail 4 Work scaffold 44 Scaffolding cloth 45 Frame scaffold 5 Form 51 Outer form 52 Inner form 6 Cover sheet 7 Curing sheet 81 Water supply pipe 82 Tank / pump device 83 Sprinkling nozzle

Claims (8)

A work scaffolding is installed at the construction site of the bridge through appropriate support, and the bridge girder reinforcement structure and formwork are assembled using this work scaffolding, and concrete is placed in the formwork to construct the bridge girder. In the construction work of the concrete bridge to
Using the work scaffolds installed on the side and below the bridge girder, covering the outside of the bridge girder by providing a covering surface at positions appropriately spaced from the left and right side surfaces and the bottom surface of the bridge girder, respectively.
A water supply pipe with a watering nozzle is disposed inside the area covered by the covering surface,
A method for curing a concrete bridge girder, comprising curing water after demolding by spraying water into the region from the watering nozzle to maintain the region in a wet state. On the constructed bridge body (bridge pier, abutment or bridge girder), a scaffold suspension means movable in the direction of the bridge axis is installed, and a formwork and a frame are formed on the front end side of the bridge body constructed using the scaffold suspension means. A concrete bridge that assembles a reinforcing bar structure and a formwork in units of a construction block of a predetermined length while suspending a work scaffold, casts concrete into the formwork, and sequentially extends bridge girders in the direction of the bridge axis. In the construction work of
Using the working scaffold, covering the outside of the bridge girder by providing a covering surface at a position appropriately spaced from the left and right side surfaces of the bridge girder in the block currently under construction, the front end surface and the bottom surface, respectively.
A water supply pipe with a watering nozzle is disposed inside the area covered by the covering surface,
By spraying water into the area from the watering nozzle and maintaining the inside of the area in a moist state, the concrete after demolding in the block currently under construction is cured,
A curing method for a concrete bridge girder, wherein the curing step is repeated for each construction block while moving the covering surface and the water supply pipe together with the work scaffold in the bridge axis direction. In the curing method of the concrete bridge girder according to claim 1 or 2,
The work scaffold includes a work floor formed by laying scaffolding cloth boards substantially horizontally without gaps, and a frame formed by assembling a gate-shaped steel pipe building frame (to an appropriate height) on the work floor. With scaffolding,
The covering surface is configured by continuously connecting the work floor and a covering sheet stretched so as to face the bridge girder along vertical and horizontal frame members constituting the frame scaffold. Curing method for concrete bridge girder characterized by In the curing method of the concrete bridge girder according to claim 3,
The covering sheet is formed by joining together a plurality of unit sheets formed in a long rectangle of a predetermined dimension,
A fastener is attached to the edge of each unit sheet, and the edges of adjacent unit sheets are joined together via the fastener,
A method for curing a concrete bridge girder, characterized in that engaging means for vertical and horizontal frame members constituting the framework scaffolding are provided at the corners of each unit sheet. In the curing method of the concrete bridge girder according to claim 3 or 4,
While covering the bridge surface of the bridge girder with a curing sheet,
By extending the upper edge part of the covering sheet stretched so as to face both the left and right side surfaces of the bridge girder and overlapping the left and right edge parts of the curing sheet,
A method for curing a concrete bridge girder, which integrally covers a range from a bridge surface of the bridge girder to both left and right side surfaces. In the curing method of the concrete bridge girder according to claim 2,
While installing the work scaffold over at least the range from the current construction block to the next construction block,
The method for curing a concrete bridge girder is characterized in that the covering surface is also provided so as to integrally cover at least a range from a block being currently constructed to a next construction block. In the curing method of the concrete bridge girder according to claim 6,
The bridge girder is a box girder having a hollow portion having a substantially rectangular cross section,
A method for curing a concrete bridge girder, wherein the region covered by the covering surface is integrally communicated from the outside of the bridge girder to the hollow portion. In the curing method of the concrete bridge girder as described in any one of Claim 2, 6, or 7,
On the constructed bridge body, a tank and a pump device for supplying water to the water supply pipe are installed,
A curing method for a concrete bridge girder, wherein the tank and the pump device are moved together with the covering surface and the work scaffold in a bridge axis direction in a construction block unit.

Images