Aseismatic reinforcing method

Abstract

To provide an aseismatic reinforcing method causing no deformation in a neighboring structure and causing no outflow of polluted water.SOLUTION: A seismic reinforcement method comprises the steps of: installing a reinforcement frame so as to surround a columnar structure on the ground; press-fitting the reinforcement frame into the ground by press-fitting means; sucking a ground structure taken in between the columnar structure and the reinforcement frame by suction means; and filling the space between the columnar structure and the reinforcement frame press-fitted into the ground with a filler.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a method for seismic reinforcement of a columnar structure. [Background technology]

[0002] Known methods for reinforcing columnar structures such as bridge piers include the reinforced concrete (RC) lining method and the steel plate lining method. The RC lining method involves placing reinforcing bars around the columnar structure as reinforcing materials, pouring concrete, and integrating it with the columnar structure to reinforce it. The steel plate lining method involves placing steel plates around the columnar structure instead of reinforced concrete, filling the gap between the columnar structure and the steel plates with a filler such as non-shrink mortar or epoxy resin, and integrating the columnar structure with the steel plates to reinforce it.

[0003] As an example of the steel plate wrapping method, a method is known in which a support pole serving as a columnar structure is surrounded by a reinforcing frame made of steel plates above ground, and the reinforcing frame is pressed into the ground (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 4490833 Summary of the Invention [Problem to be solved by the invention]

[0005] In the conventional method described above, the tip of the reinforcing frame is bent toward the support pillar, and multiple high-pressure injection pipes are provided around the reinforcing frame to inject high-pressure fluid, thereby preventing soil and sand from being drawn into the reinforcing frame and pushing obstacles such as rocks to the side, thereby preventing press-in failures.

[0006] However, the above-mentioned conventional method pushes soil and obstacles to the side of the reinforcing frame, which may cause deformation of nearby structures such as river retaining walls, and if there is a river nearby, there is a risk of polluted water leaking out. [Means for solving the problem]

[0007] The present invention has been made in view of the above-mentioned problems, and includes the steps of: installing a reinforcing frame on the ground so as to surround a columnar structure; pressing the reinforcing frame into the ground using a pressing means; sucking ground components trapped between the columnar structure and the reinforcing frame using a suction means; and filling the space between the columnar structure and the reinforcing frame pressed into the ground with a filler. A seismic retrofitting method is provided, including: [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a method of earthquake-resistance reinforcement that does not cause deformation of neighboring structures and does not cause the outflow of polluted water. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing an example of the structure of a bridge. [Figure 2] 1A and 1B are diagrams illustrating a conventional method for seismic reinforcement of a bridge pier as an example of a columnar structure. [Figure 3] 1 is a diagram illustrating this method for seismic reinforcement of bridge piers. [Figure 4] A diagram explaining the installation position of the reaction bearing material, the relative positions of the pier and reinforcing frame, and the installation position of the press-in jack. [Figure 5] 1 is a flowchart showing the workflow of the present method for seismic reinforcement of bridge piers. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present invention is a method for seismic reinforcement of a columnar structure, and can be applied to any columnar structure that requires seismic reinforcement. In the following, the columnar structure will be described as a bridge pier, but the present invention is not limited to this.

[0011] The structure of a bridge will be described with reference to Figure 1. A bridge is composed of a superstructure 10 and a substructure 20. The superstructure 10 directly supports pedestrians and vehicles, while the substructure 20 supports the superstructure 10. The superstructure 10 includes a deck 11, which is the portion on which pedestrians and vehicles pass, and a main girder 12, which supports the load of the entire superstructure, including the deck 11, and transmits it to the substructure 20. Between the superstructure 10 and the substructure 20, bearings 30 are installed to absorb deformation and absorb expansion and contraction of the superstructure 10 due to temperature changes, thereby improving earthquake resistance. In addition, expansion devices (joints) 31 are installed in the gaps at both ends of the superstructure 10's length to enable expansion and contraction and eliminate unevenness and gaps in the road surface. The gaps are provided as clearance to prevent the main girders 12 from contacting and damaging the abutments 21 when the superstructure 10 deforms due to temperature changes, drying shrinkage, earthquakes, etc.

[0012] The substructure 20 includes abutments 21 and piers 22. The abutments 21 are substructures that support the start and end points of the bridge, and the piers 22 are substructures that support the middle of the bridge. The abutments 21 have the function of smoothly transmitting to the ground the weight of the superstructure 10 as well as the load of people and vehicles, and forces received from earthquakes, wind, etc., and also function as retaining walls to prevent the flow of ground components (e.g., soil and sand) that make up the ground behind the abutments 21. The piers 22 are provided according to the length of the bridge, and, like the abutments 21, have the function of smoothly transmitting to the ground the weight of the superstructure 10 as well as the load of people and vehicles, and forces received from earthquakes, wind, etc.

[0013] The abutment 21 has a vertical wall 23, a parapet wall 24 constructed on the vertical wall 23, a base plate (footing) 25 constructed below the vertical wall 23, and a wing wall 26 constructed on the back surface of the vertical wall 23. The vertical wall 23 has the function of suppressing back surface earth pressure, and transmits the load of the superstructure 10 to the footing 25 via supports 30. The parapet wall 24 is a low wall extending vertically provided on the vertical wall 23. The footing 25 is a structure with an expanded installation area in order to reduce the load transmitted from the vertical wall 23 and transmit it to the ground. The wing 26 is a wall provided to protect the soil and sand behind the abutment 21.

[0014] The pier 22 has a beam portion 27, a column portion 28, and a footing 29. The beam portion 27 has a flat surface on which a bearing 30 is installed, and functions to transmit the load from the bearing 30 to the column portion 28. The column portion 28 supports the beam portion 27, which is placed on the ground or on water, and extends from the beam portion 27 into the ground, and functions to transmit the load from the beam portion 27 to the footing 29. The footing 29 has a function similar to that of the footing 25 of the abutment 21.

[0015] Bridges deteriorate over time, but to continue to be used after that, they require proper inspection, repair, reinforcement, and maintenance to extend their lifespan. To carry out appropriate repairs and reinforcement, it is necessary to select an appropriate construction method taking into account the bridge's location and other factors.

[0016] A method shown in FIG. 2 is known as a conventional earthquake-resistant reinforcement method for reinforcing a bridge pier 22, which is an example of a columnar structure (see Patent Document 1 above for details). The conventional earthquake-resistant reinforcement method is one of the steel plate wrapping methods, in which, as shown in FIG. 2(a), at least one reinforcing steel plate 40 is used to assemble a frame on the ground so that the four sides of a column 28 of a rectangular cross section made of reinforced concrete of the bridge pier 22 are covered, forming a reinforcing frame. A reaction force receiving member 41 is installed on the column 28 above the reinforcing frame, spaced apart from the reinforcing frame. A press-in jack 42 is then installed between the reinforcing frame and the reaction force receiving member 41 as a press-in means. The press-in jack 42 is extended to press the reinforcing frame into the ground.

[0017] As shown in Figure 2(b), the tip of the reinforcing steel plate 40 in the depth direction underground is bent toward the column portion 28, so that while the reinforcing frame is being pressed in with the press-in jack 42, ground constituents (soil, sand, etc.) are pushed out to the outside of the reinforcing frame and are not taken inside the reinforcing frame.

[0018] A pipe 43 is installed on the outer surface of the reinforcing frame, and as shown in Figure 2(b), a high-pressure fluid (e.g., water) 44 is sprayed from the pipe 43 to push obstacles 45 such as gravel and boulders, which are ground constituents present underground, out of the reinforcing frame and prevent them from being drawn inside the frame.

[0019] The gap between the side of the pillar 28 and the reinforcing steel plate 40 that constitutes the reinforcing frame is approximately 30 mm, and as shown in Figure 2(c), mortar 46 is filled in the four corners of the gap between the reinforcing frame and the pillar 28, and sand 47 or the like is filled in the other parts (between the corners). Note that in Figure 2(c), the pillar 28 is constructed of reinforced concrete, and reinforcing bars 48 are shown in the cross section of the pillar 28.

[0020] As shown in Figure 2(b), the above-mentioned conventional earthquake-resistant reinforcement method pushes soil and obstacles 45 outward (to the side) of the reinforcement frame, so if a structure such as a river retaining wall is located nearby, the structure may be subjected to earth pressure, causing deformation. Also, with the above-mentioned conventional earthquake-resistant reinforcement method, if the bridge pier to be reinforced is located near a river, there is a risk that the injected fluid (high-pressure water) will flow into the river as polluted water.

[0021] The construction method of the present invention (hereinafter referred to as the present construction method) is a seismic reinforcement method that does not cause deformation of neighboring structures and does not cause the outflow of polluted water. The present construction method will be described in detail with reference to Figs. 3 to 5.

[0022] FIG. 3 is a diagram illustrating this construction method. As with conventional earthquake-resistant reinforcement construction methods, as shown in FIG. 3(a), at least one reinforcing steel plate 50 is assembled on the ground into a frame shape to surround the periphery of the column 28 made of reinforced concrete and having a rectangular cross section of the pier 22 (covering the four side surfaces of the column 28), forming a reinforcing frame. The reinforcing frame is formed by, for example, welding a plurality of metal plates facing each side surface of the column 28 so as to form a frame-like object with a rectangular cross section that is the same as the cross-sectional shape of the column 28. If the cross-sectional shape of the column 28 is circular, the reinforcing frame is assembled so as to form a frame-like object with a circular cross section. The metal plate may be flat, or may be processed to have an uneven surface.

[0023] Next, reaction force receiving materials 51 are installed on the pillars 28 at a height above the reinforcing frame and spaced apart from the reinforcing frame. At least one reaction force receiving material 51 is installed on each of the four side surfaces of the pillars 28. In the example shown in FIG. 3(a), three reaction force receiving materials 51 are installed on each side surface of the pillars 28.

[0024] Then, press-in jacks 52 are installed as a press-in means between the reinforcing frame and the reaction force receiving material 51. One press-in jack 52 is installed for each reaction force receiving material 51. After the press-in jacks 52 are installed, they are extended to press-in the reinforcing frame by pushing it into the ground. As shown in FIG. 3(a), since multiple press-in jacks 52 are installed, the multiple press-in jacks 52 are controlled to extend at the same speed.

[0025] As shown in Fig. 4, the reaction force receiving material 51 has a first surface 53 that extends perpendicularly to the side surface of the pillar portion 28 and has a predetermined area, and a second surface 54 that is adjacent to the side surface of the pillar portion 28. After the reaction force receiving material 51 is placed with the second surface 54 adjacent to the pillar portion 28, it is fixed to the pillar portion 28 using a fixing member such as an anchor 55.

[0026] The press-fit jack 52 is provided with flanges with flat surfaces on both ends, and is arranged so that the flange on one end is adjacent to the first surface 53 of the reaction force receiving member 51. The press-fit jack 52 is arranged so that the flange on the other end is adjacent to a connecting fitting 56 that clamps the upper end of the reinforcing steel plate 50 that constitutes the reinforcing frame. The flanges on both ends, the reaction force receiving member 51, and the connecting fitting 56 are connected using connecting members such as bolts and nuts.

[0027] The press-fitting jack 52 is attached in a contracted state and extends when the reinforcing frame is pressed in. The press-fitting jack 52 includes, but is not limited to, a cylinder and a rod, and when contracted, the rod is stored in the cylinder, and when extended, the rod protrudes from the cylinder. The press-fitting jack 52 may be a mechanical jack (e.g., a screw jack), a liquid-operated jack (e.g., a hydraulic jack), or an air-operated jack (air jack).

[0028] By extending the press-fitting jack 52, the reinforcing frame is pressed into the ground from its tip. When the press-fitting jack 52 is fully extended, the press-fitting jack 52 is temporarily retracted, and as shown in FIG. 3(b), a support 57 is installed on the reinforcing frame as a height adjustment member to adjust the height from the ground to the top of the reinforcing frame. The press-fitting jack 52 is then extended again, allowing the reinforcing frame to be pressed in again. The number of support 57 installed between one press-fitting jack 52 and the reinforcing frame is not limited to one, but multiple support 57 can be installed in the press-fitting direction. When installing multiple support 57, the above-mentioned process of pressing the reinforcing frame, retracting the press-fitting jack 52, installing the support 57, and extending the press-fitting jack 52 is repeated, allowing each support 57 to be added one by one.

[0029] In this method, the tip (bottom end) of the reinforcing frame is not bent toward the column 28, as shown in Figure 4. In addition, the gap t from the side of the column 28 to the reinforcing steel plate 50 that constitutes the reinforcing frame is 50 mm to 300 mm, which is wider than in conventional earthquake-resistant reinforcement methods. For this reason, in this method, when the reinforcing frame is pressed in by the press-in jack 52, soil, sand, gravel, and other ground constituents are trapped inside the reinforcing frame.

[0030] Therefore, in this construction method, after removing the press-in jack 52, or the press-in jack 52 and the support 57, the soil and sand trapped inside the reinforcing frame are sucked out from the opening on the ground by a vacuum truck as a suction means. Water, gravel, etc. may be trapped inside the reinforcing frame, but this water and gravel are also sucked out together with the soil and sand.

[0031] The soil and sand trapped inside the reinforcing frame may form large clumps that cannot be suctioned. For this reason, a high-pressure washer or the like can be used to agitate the soil and sand trapped inside the reinforcing frame with a jet of high-pressure water, eliminating large clumps and making suction easier. Here, we have described agitating the soil and sand by jetting high-pressure water, but the method is not limited to jetting high-pressure water and can also be jetting compressed air as long as it can loosen the soil and sand.

[0032] After the soil and sand trapped inside the reinforcing frame is sucked out, the hollow space inside the reinforcing frame is filled with a filler material such as concrete.

[0033] After the reinforcing frame is pressed in, the soil and sand that has been trapped inside the reinforcing frame can be sucked out and filled with filler. Alternatively, the soil and sand can be repeatedly sucked out each time the reinforcing frame is pressed in to a specified depth, and once the reinforcing frame has been pressed in to the specified designed depth and the soil and sand have been sucked out, the hollow portion inside the reinforcing frame can be filled with filler.

[0034] The volume of the hollow space inside the reinforcing frame is larger than that of conventional seismic reinforcement methods, so filling it with filler requires a large amount of material. Filling it all with mortar would be costly. On the other hand, if it were filled with inexpensive soil and sand, the gap between the column 28 and the reinforcing frame would be large, causing the filled soil and sand to flow inside, resulting in no reinforcement effect. Therefore, it is possible to fill it with concrete, which is cheaper than mortar.

[0035] By using concrete as the filler and integrating the pillars 28 with the reinforcing plates, a large cross section can be achieved, ensuring sufficient earthquake resistance.

[0036] In addition, for areas where groundwater exists in the ground, it is desirable to use concrete that does not separate even underwater and contains chemical admixtures that dissolve in water to increase viscosity (underwater non-segregating concrete). This allows the concrete to be poured by free fall even during underwater construction.

[0037] The jacking pressure and press-in height (depth) of the press-in jack 52 are controlled by a computer 58, which serves as control means electrically connected to the press-in jack 52. If the press-in jack 52 is a hydraulic jack, it can detect the load acting on the jack from the hydraulic pressure, and the computer 58 can calculate the jack pressure from the detected load. The press-in height can be measured by wire displacement meters 59, which serve as measurement means provided at the four corners of the column 28, as shown in FIG. 3(b). The wire displacement meters 59 measure the press-in height in 0.1 mm increments based on the unwound length of the wire.

[0038] Therefore, the press-fitting jack 52 can be operated while checking the jack pressure and press-fitting height of the press-fitting jack 52, and the reinforcing frame can be press-fitted.

[0039] There may be obstacles on the ground surface or underground, such as gravel having a diameter of several tens to several hundreds of millimeters, that hinder the pressing in of the reinforcing frame. If such obstacles exist, the reinforcing frame cannot be pressed in properly.

[0040] Therefore, if an obstacle is found, a backhoe is used as an excavation means to excavate a few meters (for example, about 1.5 m) of the surface, and the excavated area is replaced with mountain sand or the like that does not contain the obstacle. After that, a reinforcing frame is installed and the reinforcing frame is pressed in using the pressing jack 52.

[0041] The presence of obstacles in the ground surrounding the pier 22 can be confirmed by a sounding test. A sounding test involves inserting a resistive element, such as a vane or cone attached to the tip of a rod, into the ground within a test area and applying loads such as penetration or rotation to investigate properties such as the hardness and compaction of the ground. Sounding tests include the standard penetration test, portable cone penetration test, screw weight penetration test, and vane test. The standard penetration test is commonly used, and is performed using holes drilled by a boring machine or similar. Therefore, the presence of such obstacles can be confirmed by conducting exploration (exploratory boring) using the holes drilled by boring. Exploration boring can also be used to confirm whether the reinforcement area is the same as the as-built drawings, for example, whether the height from the ground surface to the footing is the same as the height from the ground surface to the footing in the as-built drawings.

[0042] Figure 5 is a flowchart showing the work flow of this method for seismic reinforcement of bridge piers. Work begins in step 100, and in step 101, reaction force receiving members 51 are installed at a predetermined height on each side of column portion 28 exposed above ground using anchors 55. In step 102, reinforcing steel plates 50 are assembled on the ground to form a reinforcing frame, which is then installed. The reinforcing frame may be made of multiple steel plates welded together. The surface of the reinforcing frame may be painted to prevent deterioration due to rust, etc.

[0043] In step 103, a press-in jack 52 is installed between the reinforcing frame and the reaction force receiving member 51. In step 104, the press-in jack 52 is extended, and the reinforcing frame is pressed into the ground. In step 105, when the press-in jack 52 is fully extended, the press-in jack 52 is contracted, and a support 57 is installed between the press-in jack 52 and the reinforcing frame. In step 106, the press-in jack 52 is extended again, and the reinforcing frame is pressed in until the height from the ground to the top end of the reinforcing frame reaches a predetermined height.

[0044] In step 107, the press-in jack 52 and the support pillar 57 are removed. In step 108, a vacuum truck is used to suck up the soil and sand that has been trapped inside the reinforcing frame on the periphery of the pillar portion 28. In step 109, it is determined whether the height of the reinforcing frame that has been pressed into the ground is the designed height. If it is not the designed height, the process returns to step 102, where another reinforcing frame is assembled on top of the reinforcing frame that has been pressed into the ground, and the pressed-in reinforcing frame and the assembled reinforcing frame are connected together by welding or the like, and the process of pressing in again using the press-in jack 52 is repeated.

[0045] For example, if the height of the reinforcing frame that can be assembled at one time is about 2 m and about 6 m of underground pillar portion 28 is to be reinforced with the reinforcing frame, steps 102 to 108 will be repeated three times.

[0046] If it is determined that the design height has been reached, the process proceeds to step 110, where the hollow space around the outer periphery of the column 28, inside the reinforcing frame, is filled with a filler. Then, in step 111, the work ends. Because the filler is concrete, the column 28 and the reinforcing frame are integrated by filling with concrete. Therefore, the pier 22 has a larger cross section than the pier 22 before reinforcement, improving seismic resistance.

[0047] With this method, soil and sand are captured inside the reinforcing frame and then sucked up by a vacuum truck, so soil and sand are not pushed out to the sides, and so there is no deformation of river retaining walls located nearby. Also, because soil and sand are captured inside the reinforcing frame when pressing it in, there is no need to spray high-pressure liquid, and this also prevents polluted water from flowing into nearby rivers.

[0048] The earthquake-resistant reinforcement method of the present invention has been described in detail above with reference to the embodiments shown in the drawings. However, the present invention is not limited to the above-described embodiments, and can be modified within the scope of what a person skilled in the art can conceive, such as other embodiments, additions, modifications, deletions, etc., and any embodiment is within the scope of the present invention as long as it achieves the functions and effects of the present invention. [Explanation of symbols]

[0049] 10…Superstructure 11…Floor slab 12…Main digit 20...Substructure 21...Abutment 22...Bridge pier 23…Vertical wall 24…Battlework 25...Footing 26...Wing 27...beam part 28...Column part 29...Footing 30...Support 31…Expansion device 40...Reinforced steel plate 41...Reaction force receiving material 42...Press-in jack 43...tube 44...Obstacle 50...Reinforced steel plate 51...Reaction force receiving material 52...Press-in jack 53...First side 54...Second Side 55...Anchor 56...Connecting hardware 57...post

Claims

1. a step of installing a reinforcing frame on the ground so as to surround the periphery of the columnar structure; a step of pressing the reinforcing frame into the ground using a pressing means; a step of sucking the ground constituents trapped between the columnar structure and the reinforcing frame by a suction means; a step of filling a gap between the columnar structure and the reinforcing frame pressed into the ground with a filler; Seismic reinforcement methods, including:

2. 2. The earthquake-resistant reinforcement method according to claim 1, further comprising the steps of: after the pressing-in step, installing a height adjustment material between the pressing-in means and the reinforcing frame to adjust the height from the ground to the upper end of the reinforcing frame; and using the pressing-in means to press-in the reinforcing frame again via the height adjustment material.

3. 3. The earthquake-resistant reinforcement method described in claim 2, wherein the steps of installing the reinforcing frame, the press-fitting, installing the height adjustment material, and the re-press-fitting are repeated until the height of the reinforcing frame to be installed around the columnar structure reaches the design height.

4. The earthquake-resistant reinforcement method according to claim 1, further comprising the steps of excavating the ground around the columnar structure and replacing ground components in the excavated ground with soil and sand before the step of installing the reinforcing frame.

5. The earthquake-resistant reinforcement method according to claim 4, further comprising a step of conducting exploratory boring of the ground around the columnar structure before the step of excavating the ground.

6. 2. The earthquake-resistant reinforcement method according to claim 1, wherein the gap between each side surface of the columnar structure and each of the flat plates constituting the reinforcement frame is 50 mm to 300 mm.

7. The earthquake-resistant reinforcement method according to claim 1 , wherein the filler is concrete.

8. 8. The earthquake-resistant reinforcement method according to claim 7, wherein when filling a groundwater portion of the ground, underwater non-segregating concrete is used as the concrete.

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