Method for removing floor slab

Abstract

To provide a method for shortening the time required to remove a floor slab in a composite beam, and efficiently removing the floor slab without damaging a main girder (box girder).SOLUTION: A method for removing a floor slab includes: a process for injecting high pressure water from an upper surface side of a floor slab joined to a box girder, with slip preventive members arranged in a row toward the axial direction of the box girder, on both end parts of the box girder in a composite beam in the width direction, removing concrete, and exposing the slip preventive members arranged in a row on the end parts; a process for forming a gap with the prescribed depth that extends in the axial direction of the box girder, on the floor slab on the box girder between the slip preventive members arranged in a row on the end parts; a process for inserting an expansion member that expands when pressure is applied to its inside, into the formed gap; and a process for applying pressure to the inside of the expansion member inserted into the gap to expand the expansion member.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to a method for removing a deck in a composite girder. [Background technology]

[0002] The decks of bridges such as road bridges need to be removed and replaced with new ones due to deterioration and damage over time. The main girders and deck structures that make up bridges can be either composite or non-composite girders. In composite girders, dowel bars are installed on the girder flanges of the main girders to firmly connect the main girders to the deck constructed on top of them. For this reason, removing the deck of a composite girder is a time-consuming and labor-intensive task.

[0003] One method known for removing a deck from a composite girder is to use a high-pressure water jet to remove only the concrete from the top surface of the deck along the length of the steel girder, exposing the dowels and some of the rebar embedded in the deck, cutting the edges and then pulling it upwards (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 4875775 Summary of the Invention [Problem to be solved by the invention]

[0005] In the above-mentioned conventional technology, when the main girder of the composite girder is a box girder, it is difficult to cut the deck on the box girder without damaging it and to peel it off upward into block pieces of the required size after exposing and cutting the anti-slip members at the ends of the main girder with a high-pressure water jet. Therefore, the deck on the box girder after cutting must be removed by hand cutting or a water jet (WJ) method, etc., and there was a problem that the deck removal work for the composite girder takes time and the deck cannot be removed efficiently. [Means for solving the problem]

[0006] The present invention has been made in consideration of the above problems, and is a method for removing a deck slab in a composite girder, a step of spraying high-pressure water from the upper surface side of a deck slab made of reinforced concrete joined to a box girder in which anti-slip members are arranged in a row in the axial direction of the box girder at both ends in the width direction of the box girder of a composite girder, thereby removing the concrete and exposing the anti-slip members arranged in a row at each end; A step of forming a gap of a predetermined depth extending in the axial direction of the box girder in the deck slab on the box girder between the shear stop members arranged in a row at both exposed ends; A step of inserting an expansion member that expands by applying pressure to the inside of the expansion member into the formed gap; applying pressure to the inside of the expansion member inserted into the gap to expand the expansion member; A method for removing a deck is provided, comprising: Effect of the Invention

[0007] According to the present invention, it is possible to reduce the time required for deck removal work in a composite girder and to efficiently remove the deck without damaging the main girders (box girders) of the composite girder. [Brief description of the drawings]

[0008] [Figure 1] A diagram showing an example of a road bridge structure. [Diagram 2] This is a diagram showing a simulated composite box girder that imitates an example of a joint between a main girder and a deck in a road bridge. [Diagram 3] FIG. 1 is a diagram showing an example of a cutting device that cuts concrete using high-pressure water. [Figure 4] FIG. 4 is an enlarged view of a nozzle for spraying high-pressure water provided on the cutting device. [Diagram 5] A diagram explaining the work of removing the deck. [Figure 6] FIG. 4 is a diagram showing an example of an expansion member. [Figure 7] 11 is a flowchart showing an example of a work for removing a deck slab. [Figure 8] A diagram showing the state of the joint after the concrete was removed using high-pressure water. [Figure 9] A diagram showing how a gap is formed in the deck using a road cutter. [Figure 10] A diagram showing the state in which an expansion member is inserted into the formed gap. [Figure 11] A diagram showing the state in which the gap expands due to the expansion of the expansion member. [Figure 12] A diagram showing the deck being lifted by a hoist and removed from the box girder. [Figure 13] A diagram showing the box girder after the deck has been removed. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Figure 1 shows an example of a road bridge structure with two main girders (box girders) and a deck slab. A road bridge is one type of bridge, and other bridges include railway bridges and pedestrian bridges. A bridge is a road structure that is erected over a river or other waterway, leaving space under the girders, and is 2m or longer in length.

[0010] A road bridge 10 is composed of a substructure (subwork) such as piers, and a superstructure (superwork) that is constructed on the subwork and directly supports pedestrians, vehicles, etc. The superstructure includes supports 11 that transmit loads to the subwork, main girders 12 that support the entire superwork and extend vertically from the supports 11 that transmit loads to the subwork via the supports 11, cross girders 13 that connect the main girders 12, and a deck slab 14 that transmits the weight of pedestrians, vehicles, etc. as load to the main girders 12 and cross girders 13.

[0011] The bearing 11 may be a movable bearing that absorbs the rotation and expansion and contraction of the superstructure, or a fixed bearing that absorbs only the rotation of the superstructure, or a seismic isolation bearing that uses laminated rubber or the like for elastic fixation.

[0012] The main girder 12 may be an I-girder, a box girder, etc., depending on the shape of a vertical cross section, and may be a steel girder, a reinforced concrete girder, a PC (prestressed concrete) girder, etc., depending on the material. In the road bridge according to this embodiment, the main girder 12 is a box girder that is a box-shaped girder with a hollow interior.

[0013] The cross girder 13 is a girder that is installed to extend in the width direction of the bridge in order to distribute the load of the main girder 12. Normally, the load is shared between the main girder 12 and the cross girder 13, but if necessary, a vertical girder may be installed along the length of the bridge (the axial direction of the bridge) and the load may be shared between the main girder 12, the cross girder 13, and the vertical girder.

[0014] Like the main girders 12 and cross girders 13, the deck 14 may be constructed from materials such as steel, reinforced concrete, and precast concrete. In the road bridge according to this embodiment, the deck 14 is constructed from reinforced concrete. A deck waterproof layer 15 such as a waterproof sheet is provided on the deck 14 to prevent deterioration due to water intrusion into the deck 14, and asphalt or the like is laid on the deck waterproof layer 15 to perform paving 16.

[0015] On both ends of the bridge in the width direction, a ground cover 17, which is a step higher than the pavement 16, is provided. A protective fence 18 is provided on the ground cover 17 to prevent people, vehicles, etc. from falling off the bridge.

[0016] The deck 14 may be constructed by installing formwork, laying rebar, and pouring concrete after installing the two main girders 12 and cross girders 13, or by using precast reinforced concrete deck members. At this time, to strengthen the connection between the two main girders 12 and cross girders 13 and the deck 14, a row of dowel bars 19 bent into a horseshoe shape (U-shape) or headed rod-shaped stud dowel bars is installed as a slip prevention member at both ends of the girder flange of each main girder 12 (both ends in the width direction of the bridge).

[0017] A plurality of dowel bars 19 are provided in a row at predetermined intervals in the longitudinal direction (axial direction) of the bridge at each end of the girder flange of each main girder 12. Therefore, in Fig. 1, there are two main girders 12, and dowel bars 19 are provided in a row at both ends of each main girder 12, resulting in a total of four rows of dowel bars.

[0018] When using precast reinforced concrete deck members, holes are provided at positions corresponding to the dowel bars 19, and after the dowel bars 19 are inserted into the holes, the holes can be filled with mortar or the like to integrate the main girders 12 and deck slab 14. A girder having a structure in which the main girders 12 and deck slab 14 are integrated with the dowel bars 19 is called a composite girder. A composite girder is a girder made by overlapping different materials, and when the deck slab 14 is made of reinforced concrete, the main girders are made of materials other than reinforced concrete or concrete, such as steel.

[0019] When replacing the deck 14 in a composite girder, the pavement 16 and the deck waterproof layer 15 are removed by peeling them off, and then the concrete around the dowel bars 19 is removed using the WJ method as in the conventional technology, and the deck 14 can be removed by peeling it off upwards.

[0020] When a steel box girder is used as the main girder 12, since the dowel bars 19 are arranged in a row on both ends of the girder flange of the box girder in the width direction of the box girder, it is possible to expose and cut off the dowel bars 19 in each row. However, it is difficult to cut the deck 14 remaining on the girder flange after the cutting into block pieces without damaging the box girder immediately below it. Furthermore, if it is not cut into block pieces, the joint surface between the deck 14 and the girder flange is large, so it cannot be peeled off upwards. For this reason, the concrete on the deck 14 on the girder flange after the cutting must be removed by the WJ method or the like, which takes time and makes it impossible to remove the deck 14 efficiently.

[0021] In view of this, the present invention provides a deck slab removal method that enables efficient removal of the deck slab 14 without damaging the main girders (box girders).

[0022] This method may be explained with reference to the road bridge 10 shown in Figure 1, but to make this method easier to understand, it will be explained using a simulated composite box girder as shown in Figure 2. In addition, in the actual road bridge 10, two box girders are installed as shown in Figure 1, but since the deck slabs on both box girders can be removed using the same method, only the removal of the deck slab on one box girder will be explained below.

[0023] The simulated composite box girder includes a plurality of H-shaped steels 20 with an H-shaped cross section cut vertically, which corresponds to one main girder 12 shown in Fig. 1, and an iron plate 21 arranged to connect the upper flanges of the two H-shaped steels 20 arranged at both ends. The upper flanges of the two H-shaped steels 20 and the iron plate 21 constitute the girder flanges of the main girder 12 shown in Fig. 1, and the upper flanges of the two H-shaped steels 20a and the iron plate 21 are connected by welding a plate 22 to their undersides, for example. The iron plate 21 is supported by two H-shaped steels 20b whose upper flanges are lower in height than the two H-shaped steels 20a.

[0024] The simulated composite box girder includes horseshoe-shaped dowel bars 23 welded at regular intervals in the axial direction of the box girder to both ends of a steel plate 21 in the width direction of the box girder, which corresponds to the width direction of the bridge, and arranged in a row at each end, and a deck slab 25 made of reinforced concrete joined onto the steel plate 21. The width direction of the box girder is the direction in which the upper flanges of the two H-shaped steel bars 20a extend, sandwiching the steel plate 21. In the example shown in FIG. 2, the thickness of the deck slab 25 is formed so as to become thicker from one end to the other end in the width direction of the box girder, but it may be a constant thickness or the like.

[0025] The H-shaped steel 20 is one of the long steel materials formed into a fixed cross-sectional shape, and the two parts of the H-shaped cross section that extend almost parallel are the flanges (upper flange and lower flange), and the part connecting the upper flange and the lower flange is the web. The steel plates 21 are plates with a specified thickness and width, and multiple sheets are laid out and installed in the axial direction of the box girder.

[0026] The dowel bars 23 are provided as anti-slip members to maintain the unity of the H-shaped steel 20 and the deck slab 25. As the dowel bars 23, in addition to horseshoe-shaped dowel bars, headed studs having a rod-shaped expanded head, perforated steel dowels having a plurality of holes in a flat plate, etc. may be used.

[0027] The reinforcing bars 24 extend in two rows, upper and lower, as main reinforcements in the axial direction of the box girder, and are arranged at predetermined intervals in the width direction of the box girder. In the example shown in Fig. 2, the interval between the main reinforcements in the upper row is narrow, and the interval between the main reinforcements in the lower row is wide.

[0028] The reinforcing bars 24 are arranged at a predetermined interval in the axial direction of the box girder as shear reinforcement surrounding the outside of the main reinforcement. In the cross section shown in Fig. 2, the reinforcing bars 24 are shown extending in two stages, up and down, in the width direction of the box girder. The reinforcing bars 24 are arranged in a manner that vertically connects the reinforcing bars extending in two stages in the width direction of the box girder.

[0029] When the concrete in the shaded areas is crushed by a WJ to expose the dowel bars 23 arranged in a row at both ends of the steel plate 21, the deck 25 remains between the exposed dowel bars 23. A gap (slit) of a specified length in the axial direction of the box girder was formed at a specified depth from the top surface of the remaining deck 25 toward the lower steel plate 21, and a plate jack was inserted into the formed slit as an expansion member. It was found that when pressure was applied to the inside of the plate jack, the deck 25 split into two and peeled off from the steel plate 21.

[0030] The present invention was made based on this finding. Therefore, in this method, first, high-pressure water is sprayed from the top side of a deck 25 made of steel plates 21 on which dowel bars 23 are arranged in a row in the axial direction of the box girder at both ends in the width direction of the box girder and reinforced concrete joined onto the upper flanges of two H-shaped steel beams 20a to remove the concrete, thereby exposing the dowel bars 23 arranged in a row at each end.

[0031] To expose the dowel reinforcement 23, it may be possible to remove it by hand chipping, but it is preferable to use the WJ method, in which high-pressure water is sprayed to remove the concrete, because this method saves labor and manpower and makes it possible to remove concrete in narrow areas that are difficult to chip by hand.

[0032] In the WJ method, concrete is removed by spraying high-pressure water using a WJ cutting device 26. When removing concrete using high-pressure water, cracks are created in the concrete using water pressure, and the high-pressure water is then sprayed into the cracks, expanding them and destroying / pulverizing the concrete.

[0033] As the WJ cutting device 26, for example, the device shown in Fig. 3 can be used. The WJ cutting device 26 includes a cutting unit and a traveling unit. The traveling unit is equipped with a caterpillar (crawler) 30. While traveling in the axial direction of the box girder with the traveling unit, the WJ cutting device 26 can spray high-pressure water with the cutting unit to remove concrete and expose the lined up dowel bars 23 and parts of the reinforcing bars 24 embedded in the deck slab 25.

[0034] The cutting part and running part of the WJ cutting device 26 are connected by an arm 31. The cutting part is equipped with a nozzle that sprays high-pressure water, a rail 32 that moves the nozzle in a direction perpendicular to the running direction of the running part, and a frame 33 that supports the rail 32 and is connected to the arm 31. A pressure hose is connected to the nozzle, and high-pressure water pressurized to a predetermined pressure is supplied. Since pieces of crushed concrete are scattered by the high-pressure water sprayed from the nozzle, and the sprayed high-pressure water can reduce visibility and pose a risk of tripping, a protective cover 34 is provided around the nozzle to prevent the scattering of concrete fragments and high-pressure water.

[0035] FIG. 4 is an enlarged view of a nozzle for ejecting high-pressure water provided in the WJ cutting device 26. The nozzle 35 may be a single nozzle, but a collision nozzle consisting of two nozzles can be used, which ejects high-pressure water from the two nozzles and causes them to collide after ejection, thereby enabling control of the chipping depth. The collision nozzle ejects high-pressure water at a single point by setting an angle of 0° when ejected straight from the two nozzles and setting angles such as 10° and -10° for the ejection direction of each nozzle to eject the water at an angle to each other. The single collision point is the collision point. Since the high-pressure water disperses after collision and the energy for destroying the concrete rapidly decreases, the distance from the tip of the nozzle 35 to the collision point (depth of the collision point) can be changed by changing the angle, and the chipping depth can be controlled.

[0036] Next, a gap of a predetermined depth is formed in the deck 25 remaining on the steel plate 21 between the exposed dowel bars 23 arranged in a row at both ends, extending in the axial direction of the box girder by a predetermined length using a road cutter 40, for example, at the approximate center of the deck 25 to form a slit 41 of a predetermined length and depth. The cutting depth of the deck 25 by the road cutter 40 is a depth that does not reach the lower steel plate 21, and is a depth that cuts the lower reinforcing bars 24 arranged in two levels, one above the other. The length of the slit 41 is a length that allows an expansion member to be inserted. In addition, if the deck 25 is long in the axial direction of the box girder and replacement takes several days, a slit (width direction slit) that is perpendicular to the slit 41 and extends in the width direction of the box girder is formed using the road cutter 40 according to the length of the axial direction of the box girder to be replaced on the day.

[0037] Next, a plate jack as an expansion member that expands by applying pressure to the inside is inserted into the formed slit 41. Here, a description will be given using a plate jack as the expansion member, but the expansion member is not limited to the plate jack.

[0038] As shown in Fig. 6, the plate jack 50 is made by welding special steel plates into a bag shape, and can be expanded by supplying pressurized water or other fluid inside. The plate jack 50 is generally about 1 m long and about 2 to 3 mm thick, and expands to a thickness of about 20 to 30 mm when water or other fluid pressurized to about 4 to 6 MPa is supplied inside. Any fluid, such as water or air, may be used as long as it can expand the plate jack 50. In the following description, the fluid is assumed to be water.

[0039] The plate jack 50 has a connection port 51 that connects to a water pressure unit (e.g., a pump) as a pressurizing means for supplying pressurized water, and water pressurized to a predetermined pressure by the water pressure unit is supplied to the inside of the plate jack 50. This allows water pressure to be applied to the inside of the plate jack 50 inserted into each of the two slits 41, causing the plate jack 50 to expand.

[0040] The expansion of the plate jack 50 causes the deck 25 to crack in the cutting depth direction of the slit 41, and the deck 25 splits. At this time, because the plate jack 50 is on the upper surface side of the deck 25, a force that rotates the deck 25 upward in the direction shown by the arrow in Fig. 5(b) acts on the deck 25, and the deck 25 peels off from the steel plate 21. Also, because the concrete around the dowel reinforcements at both ends has already been removed by the WJs, the deck 25 can easily peel off and be separated from the steel plate 21. Because the deck 25 has width-direction slits formed at predetermined positions in the axial direction of the box girder, cracks appear along the width-direction slits, and the deck 25 is cut out to a predetermined length.

[0041] The deck 25 is split into two pieces in the width direction at a predetermined length in the axial direction of the box girder and separated from the steel plate 21, and can be lifted with a hoist such as a crane and carried outside the site, where it can be split into smaller pieces outside the site. Note that the deck 25 does not have to be split into smaller pieces. Also, width slits can be formed as necessary, and if the axial length of the box girder is short, width slits do not have to be formed.

[0042] The work of removing the deck 25 and the procedure of the work will be described in detail with reference to Figures 7 to 12. This work starts from step 100 of the flow chart shown in Figure 7, and first, in order to expose the dowel bars 23 arranged in a row at both ends of the steel plate 21 in the width direction of the box girder, a WJ cutting device 26 for spraying high-pressure water is prepared. The position where the dowel bars 23 are buried is confirmed by the construction drawing used when the deck slab 25 was constructed, and the WJ cutting device 26 is positioned so that high-pressure water can be sprayed at that position, and a nozzle 35 provided on the WJ cutting device 26 is connected to a high-pressure water supply facility equipped with a high-pressure pump that generates high-pressure water by a high-pressure hose.

[0043] In step 101, high-pressure water is supplied to the nozzle 35 of the WJ cutting device 26, and the high-pressure water is sprayed from the nozzle 35 to crush and remove the concrete constituting the deck 25, exposing the dowel bars 23 and a part of the reinforcing bars 24 embedded in the deck 25. At this time, the WJ cutting device 26 moves the nozzle 35 along the rail 32 in the width direction of the box girder, and moves it in the axial direction of the box girder by the running part. As a result, only the dowel bars 23 and a part of the reinforcing bars 24 embedded in the deck 25 are left, and a groove extending in the axial direction of the box girder is formed. Since the dowel bars 23 are arranged in a row at both ends on the steel plate 21, the dowel bars 23 arranged in a row at the other end of the steel plate 21 can be exposed in the same manner, not just at one end of the steel plate 21.

[0044] Fig. 8 shows the state after the concrete has been removed by high-pressure water. Only the concrete of the deck 25 is crushed and removed by the high-pressure water, while the reinforcing bars 24 and dowel bars 23 embedded inside remain without being crushed, exposing some of the reinforcing bars 24 and dowel bars 23. As a result, a groove 42 is formed extending in the axial direction of the box girder, leaving only the dowel bars 23 and some of the reinforcing bars 24 embedded in the deck 25. The groove 42 has a substantially trapezoidal cross section, as shown in Figs. 5(a) and (b).

[0045] 7 again, in step 102, slits 41 of a predetermined depth are formed in the deck 25 remaining on the steel plate 21 between the exposed dowel bars 23 arranged in a row at both ends, extending along the axial direction of the box girder. If a width-direction slit is to be formed, it is formed before starting this work.

[0046] FIG. 9 is a diagram showing a state in which a slit 41 is formed in the deck 25 by the road cutter 40. The road cutter 40 includes a blade as a disk-shaped member having a plurality of blades on the outer periphery, and an electric motor for rotating the blade. The blade is pressed against the deck 25 and rotated to form a slit 41 with a predetermined cutting depth. The slit 41 is formed in a direction perpendicular to the upper surface of the deck 25, and the cutting depth is a depth that can cut the lower reinforcing bar 24 embedded in the deck 25, but does not reach the steel plate 21 below the deck 25. Since the slit 41 is a gap provided for inserting the plate jack 50, it is formed to a length of 1 m or more in the axial direction of the box girder so that the plate jack 50 can be inserted. In FIG. 9, a width-direction slit 43 is formed in the deck 25 in the same manner.

[0047] 7 again, in step 103, plate jack 50 is inserted into formed slit 41. As shown in Fig. 10, plate jack 50 is inserted into formed slit 41, and is connected to a water supply facility that supplies water pressurized to a predetermined water pressure to a connection port 51 provided on plate jack 50 via hose 52 or the like. Hose 52 may be provided with a valve, and water at a predetermined water pressure can be supplied and the supply can be stopped by opening and closing the valve.

[0048] In step 104, water pressure is applied to the inside of the plate jack 50 inserted into the slit 41, causing the plate jack 50 to expand. When the plate jack 50 is expanded, the width of the slit 41 increases, cracks 53 occur and extend to the steel plate 21 below, and an upward rotating force acts on the deck 25, causing the deck 25 to peel off from the steel plate 21 below, as shown in Fig. 11. Furthermore, if a width-direction slit is formed, a crack will occur along the width-direction slit, and the box girder will be cut out at a predetermined length in the axial direction.

[0049] When the plate jack 50 expands by applying a water pressure of about 4 to 5 MPa, the deck 25 cracks and the internal pressure drops temporarily. However, since the plate jack 50 is made by welding special steel plates into a bag shape, once it expands, it does not shrink. Therefore, even if the internal pressure drops once, the plate jack 50 maintains its shape at that time and can be expanded by applying further water pressure. By continuing to apply water pressure in this way, the width of the slit 41 on the upper surface side formed in the deck 25 increases, and as a result, a force that rotates upward acts on the deck 25, causing the deck 25 to peel off from the iron plate 21.

[0050] In step 105, the deck 25 that has been peeled off from the steel plate 21 is lifted by a hoist 60 such as a crane and carried out of the site. As shown in FIG. 12, a hoisting fitting is attached to the deck 25, and the deck 25 is hoisted up using a wire rope 61. The hoisting fitting is, for example, a U-shaped shackle with an anchor. The hoisting fitting may be attached to the deck 25 after the deck 25 has been peeled off from the steel plate 21 and before it is lifted by the hoist 60, or may be attached to the deck 25 before the dowel reinforcement 23 is exposed in step 101 or before the slits 41 are formed in step 102.

[0051] In step 106, the removal of the deck 25 is completed. When the deck 25 is lifted by the hoist 60 in step 105, the deck 25 can be removed with almost no concrete remaining, as shown in FIG. 13. If necessary, a step can be added between steps 105 and 106, and the concrete remaining on the steel plate 21 can be removed by hand chipping or the like. Hand chipping is the work of scraping off the concrete by hand using a hand breaker or the like. The concrete remaining on the steel plate 21 may be removed by cutting it using a WJ cutting device 26 by spraying high-pressure water.

[0052] The expanded plate jack 50 can be pressed back to its original flat state using a press machine, such as a hydraulic press.

[0053] The simulated composite box girder shown in Figure 2 was 4m wide and 2m long, and the time taken by two workers to remove the deck 25 by hand and by this method was measured. The manual removal took 400 minutes, while the removal by this method took 357 minutes, a reduction in work time of 43 minutes.

[0054] Therefore, by adopting this method, it is possible to shorten the work time and efficiently remove the deck without damaging the main girders (box girders).

[0055] So far, the deck removal method of the present invention has been described in detail with reference to the embodiment shown in the drawings, but the present invention is not limited to the above-mentioned embodiment and can be modified within the scope of what a person skilled in the art can imagine, such as other embodiments, additions, modifications, deletions, etc., and any aspect is included in the scope of the present invention as long as it achieves the functions and effects of the present invention. [Explanation of symbols]

[0056] 10...Road bridge 11...Support 12…Main digit 13…Horizontal girder 14…Floor slab 15…Floor slab waterproof layer 16...Pavement 17...Earth cover 18...protective fence 19…Gibber muscle 20, 20a, 20b…H section steel 21...Iron plate 22…board 23…Gibber muscle 24…Reinforced concrete 25…Floor slab 26…WJ cutting device 30…Crawler 31…Arm 32…Rail 33…Frame 34…Protective cover 35…Nozzle 40…Road cutter 41...Slit 42...Groove 43…Width direction slit 50…Board jack 51...Connection port 52…Hose 53…Crack 60...lifting machine 61...Wire rope

Claims

1. A method for removing a deck slab in a composite girder, comprising: a step of spraying high-pressure water from the upper surface side of a deck slab made of reinforced concrete joined to a box girder in which anti-slip members are arranged in a row in the axial direction of the box girder at both ends in the width direction of the box girder of the composite girder, thereby removing the concrete and exposing the anti-slip members arranged in a row at each end; A step of forming a gap of a predetermined depth extending in the axial direction of the box girder in the deck slab on the box girder between the shear stop members arranged in a row at both exposed ends; A step of inserting an expansion member that expands by applying pressure to the inside of the expansion member into the formed gap; applying pressure to the inside of the expansion member inserted into the gap to expand the expansion member; A method for removing the deck, including:

2. The reinforcing bars embedded in the deck are arranged vertically in two tiers, one above the other, The deck removal method according to claim 1 , wherein in the step of forming the gap, a gap is formed that is deep enough to extend from the top surface of the deck beyond the lower rebar and not reach the box girder.

3. The composite girder has two of the box girders, The deck removal method according to claim 1 or 2, wherein the exposing step, the forming step, the inserting step, and the expanding step are carried out for each of the two box girders.

4. The deck removal method according to claim 1 or 2, further comprising the step of forming a second gap of a predetermined depth extending in the width direction of the box girder in the deck on the box girder between the anti-slip members.

5. 3. A method for removing a deck as described in claim 1 or 2, wherein in the process of exposing the anti-slip member, a collision nozzle is used in which the high-pressure water is sprayed from two nozzles and the cutting depth is controlled by causing collision, and the concrete is cut while controlling the cutting depth.

6. The deck removal method according to claim 1 or 2, further comprising the step of lifting the deck detached from the box girder by the expanding step and removing it from above the box girder.

7. The method for removing a deck slab according to claim 1 or 2, further comprising a step of pressurizing water by a pressurizing means and supplying the water into the expansion member.

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