Repair method and repair structure for handrail pipes on inspection roads

Abstract

To conduct a repair work for recovering the soundness (impact resistance) of a handrail pipe of an inspection path by a low-cost and simple method.SOLUTION: A method for repairing a handrail pipe made of a glass fiber reinforced resin and provided in an inspection path, comprises: a first step of attaching a first fiber sheet containing reinforcing fibers to a position at least covering a repair part of the handrail pipe such that an orientation direction of the fibers is a direction along an axis of the handrail pipe; and a second step of attaching a second fiber sheet containing reinforcing fibers from above the first fiber sheet such that an orientation direction of the fibers is a direction along a circumference of the handrail pipe.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a technique for repairing handrail pipes on inspection roads. [Background technology]

[0002] Inspection tracks are installed alongside bridges, tunnels, etc., and are inspected by close visual inspection every five years. Known inspection tracks include those made of steel and GFRP (Glass Fiber Reinforced Plastics). Steel inspection tracks have problems such as difficulty in transporting heavy machinery in mountainous areas, and corrosion and deterioration due to salt damage and the spraying of snow-melting agents.

[0003] On the other hand, GFRP inspection roads are lightweight and have excellent corrosion resistance, electrical insulation, heat insulation, and shock absorption properties, so they are widely used in narrow mountainous areas where it is difficult to transport heavy machinery and in areas prone to salt damage.

[0004] Here, as a measure to protect workers from falls, regular inspections are carried out by hanging a safety belt from the handrail pipe of the inspection path and tying this safety belt to the worker with a string-like lanyard. If a worker accidentally falls from the inspection path, an impact load will be applied to the handrail pipe via the lanyard and safety belt, so the handrail pipe of the inspection path must be impact resistant. Therefore, if damage is found to the handrail pipe of the inspection path, repair work must be carried out promptly to restore the integrity (impact resistance) of the handrail pipe.

[0005] Previously, when damage was found in the handrail pipes of inspection routes, long spans of the pipes had to be replaced to ensure the continuity of the fibers, which was costly and time-consuming, so improvements were needed.

[0006] Patent Document 1 discloses a technique for reinforcing a metal pipe column by arranging fiber sheets such as aramid fiber in the axial and circumferential directions, Patent Document 2 discloses a technique for reinforcing a steel chimney by arranging a strand sheet made of aramid fiber in the axial direction, and Patent Document 3 discloses a technique for reinforcing a columnar body made of concrete, steel, or the like by arranging a reinforcing fiber sheet in the circumferential direction. Patent Documents 1 to 3 disclose techniques related to reinforcement methods, but do not disclose repair methods that take impact resistance into consideration. Furthermore, Patent Documents 2 and 3 disclose techniques for reinforcing one of the axial and circumferential directions, but do not disclose techniques for reinforcing both the axial and circumferential directions.

[0007] Patent Document 4 discloses a method for repairing a hollow structure in which a fiber-reinforced resin tape made of fiber bundles of reinforcing fibers impregnated with a thermoplastic resin is used to cover the damaged area, and then a reinforcing fiber sheet is attached from above using an adhesive to cover the entire structure. Patent Document 4 discloses a repair method that takes into consideration adhesive strength and appearance, but does not disclose a repair method that takes into consideration impact resistance. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-303715 [Patent Document 2] Japanese Patent Application Laid-Open No. 2018-9334 [Patent Document 3] Japanese Patent Application Laid-Open No. 2013-185366 [Patent Document 4] JP 2015-151836 A Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention aims to realize repair work to restore the soundness (impact resistance) of handrail pipes on inspection paths in a low-cost and simple manner. [Means for solving the problem]

[0010] In order to solve the above problems, the repair method of the present invention is (1) a method for repairing a handrail pipe made of glass fiber reinforced resin and installed in an inspection path, characterized by having a first step of attaching a first fiber sheet containing reinforcing fibers to a position covering at least the repair area of ​​the handrail pipe so that the orientation direction of the fibers is along the axial direction of the handrail pipe, and a second step of attaching a second fiber sheet containing reinforcing fibers on top of the first fiber sheet so that the orientation direction of the fibers is along the circumferential direction of the handrail pipe.

[0011] (2) The repair method described in (1) above, wherein the first fiber sheet is a strand sheet in which rod-shaped strands made of fiber bundles of continuous reinforcing fibers hardened with resin are arranged in one direction and pulled together like a curtain, or a reinforcing fiber sheet in which reinforcing fibers are arranged in one direction, and the second fiber sheet is the reinforcing fiber sheet.

[0012] (3) A repair method according to (2) above, characterized in that the strands in the strand sheet are connected to each other by weft threads.

[0013] (4) A repair method according to any one of (1) to (3) above, characterized in that the reinforcing fibers contained in the first and second fiber sheets are aramid.

[0014] (5) A repair method according to any one of (1) to (4) above, characterized in that it further comprises a third step of applying a finishing coat over the second fiber sheet.

[0015] In order to solve the above problems, the repair structure of the present invention is (6) a repair structure for a handrail pipe made of glass fiber reinforced resin and installed in an inspection path, characterized in that it has a first fiber sheet containing reinforcing fibers arranged to cover at least the repair area of ​​the handrail pipe, and a second fiber sheet containing reinforcing fibers laminated to the first fiber sheet, wherein the reinforcing fibers in the first fiber sheet are oriented in a direction along the axial direction of the handrail pipe, and the reinforcing fibers in the second fiber sheet are oriented in a direction along the circumferential direction of the handrail pipe. [Effects of the Invention]

[0016] According to the present invention, repair work to restore the soundness (impact resistance) of handrail pipes on inspection paths can be carried out at low cost and in a simple manner. [Brief explanation of the drawings]

[0017] [Figure 1] This is a front view of a portion of the handrail pipe of the inspection path. [Figure 2] A cross-sectional view of a handrail pipe. [Figure 3] FIG. 1 is an explanatory diagram of a three-point bending test. [Figure 4] 1 is a graph showing the test results of a three-point bending test, illustrating the relationship between load and vertical displacement. DETAILED DESCRIPTION OF THE INVENTION

[0018] FIG. 1 is a front view (external view seen from the radial direction) of a portion of a handrail pipe in an inspection path, with a perspective view of the area covered with a repair sheet. FIG. 2 is an AA' cross-sectional view of the handrail pipe taken along AA' in FIG. 1. Referring to these figures, the handrail pipe 1 is a GFRP pipe installed along an inspection path installed in a bridge, tunnel, etc. When a repair area 1a, such as a defect, is found in a portion of the handrail pipe 1, repair work is carried out using a first fiber sheet 11 and a second fiber sheet 12. In FIG. 1, the first fiber sheet 11 and the second fiber sheet 12 are collectively referred to as the repair sheet 2.

[0019] The first fiber sheet 11 contains reinforcing fibers and is attached to a position that covers at least the repair area 1a. The reinforcing fibers contained in the first fiber sheet 11 are oriented in a direction along the axial direction of the handrail pipe 1. In this specification, attaching the first fiber sheet 11 so that the reinforcing fibers are oriented along the axial direction may be rephrased as attaching the first fiber sheet 11 in the axial direction.

[0020] The fixed length of the first fiber sheet 11 (the length in the axial direction of the handrail pipe 1) may be set to an appropriate length that satisfies the desired impact resistance, for example, a fixed length of approximately 200 mm from the repair point 1a may be ensured.

[0021] The second fiber sheet 12 contains reinforcing fibers and is attached onto the first fiber sheet 11. The reinforcing fibers contained in the second fiber sheet 12 are oriented in a direction along the circumferential direction of the handrail pipe 1. In this specification, attaching the second fiber sheet 12 so that the reinforcing fibers are oriented along the circumferential direction may be referred to as attaching the second fiber sheet 12 in the circumferential direction.

[0022] A strand sheet or a reinforcing fiber sheet, more preferably a strand sheet, is used for the first fiber sheet 11. By using a strand sheet, the soundness (impact resistance) of the handrail pipe 1 can be more effectively restored.

[0023] (About strand sheets) A strand sheet is a rod-shaped strand formed by bundling continuous fibers made of predetermined reinforcing fibers and then impregnating and curing the fiber bundles with resin, aligning the strands in one direction, and then aligning them in the longitudinal direction like a curtain to form a sheet. Reinforcing fibers can be carbon fibers, metal fibers, ceramic fibers, organic fibers, or glass fibers. Metal fibers can be titanium fibers, steel fibers, or the like. Ceramic fibers can be basalt fibers, or the like. Organic fibers can be aramid, nylon, vinylon, or the like. These fibers can be used alone or as hybrid fibers containing multiple types. Among these fibers, aramid has particularly excellent impact resistance and is therefore suitable for use in the repair method of the present invention.

[0024] The resin to be impregnated and cured can be a thermosetting resin such as a room temperature curing or thermosetting epoxy resin, vinyl ester resin, MMA resin, unsaturated polyester resin, or phenol resin, or a thermoplastic resin such as nylon or vinylon. The amount of resin impregnation can be set to, for example, 30 to 70% by mass relative to 100% by mass of the strand sheet.

[0025] The strands can be connected to each other using weft threads. The weft threads can be made by bundling together a plurality of glass fibers or organic fibers having a diameter of 2 to 50 μm, for example. Nylon, vinylon, etc. are suitable organic fibers used for the weft threads. The spacing between the weft threads (the spacing between the weft threads in the longitudinal direction of the sheet) can be appropriately selected, for example, within the range of 6 to 10 cm, taking into account the handleability of the strand sheet.

[0026] By using a strand sheet as the first fiber sheet 11, it is no longer necessary to impregnate resin between the reinforcing fibers at the work site, and therefore it is possible to suppress a decrease in bending rigidity and bending strength due to insufficient impregnation.

[0027] The weight of the reinforcing fiber is preferably 600 g / m 2 More preferably, it is 800 g / m or more.2 That's all. The fiber weight is 1m 2 This is calculated from the number of reinforcing fiber bundles used in the strand sheet. By increasing the weight of the reinforcing fiber, the rigidity of the handrail pipe 1 can be effectively restored.

[0028] The strand sheet can be attached to the outer surface of the handrail pipe 1 using, for example, a room temperature curing epoxy resin. That is, a putty-like resin made of a room temperature curing epoxy resin or the like is applied to the outer surface of the handrail pipe 1, and the strand sheet is embedded in this applied resin, thereby attaching the strand sheet as the first fiber sheet 11.

[0029] When the strand sheet is attached, each rod-shaped strand extends along the axial direction of the handrail pipe 1. In other words, a repair structure is presented in which multiple strands are arranged along the axial direction of the handrail pipe 1.

[0030] (About reinforced fiber sheets) The reinforcing fiber sheet has a reinforcing fiber layer in which reinforcing fibers are arranged in one direction. Reinforcing fibers can be carbon fiber, metal fiber, ceramic fiber, organic fiber, or glass fiber. Details of each reinforcing fiber are the same as those for strand sheets, so a detailed explanation will be omitted. Reinforcing fiber sheets are lightweight and have high rigidity and strength, so there is little increase in dead load due to reinforcement. They also have the advantages of causing less damage to the base material of the handrail pipe 1 compared to the patch plate method, and being less susceptible to corrosion after construction, making them suitable for inspection roads exposed to wind and rain. Aramid can be preferably used as the reinforcing fiber.

[0031] To prevent the reinforcing fibers constituting the reinforcing fiber layer from becoming loose, the reinforcing fiber layer may be sandwiched and held between resin-permeable sheets. The resin-permeable sheet may be, for example, a biaxial or triaxial mesh or cloth made of glass fibers or organic fibers with a diameter of 2 to 50 μm. The spacing between the warp and weft threads constituting the mesh is preferably 1 to 10 mm, more preferably 2 to 50 mm. As a method for holding the reinforcing fiber layer using a biaxial resin-permeable sheet formed in a mesh shape, for example, a method can be used in which the surfaces of the warp and weft threads of the resin-permeable sheet are pre-impregnated with a low-melting-point thermoplastic resin, the resin-permeable sheets are laminated on both sides of the reinforcing fiber layer, and the sheets are heated and compressed to fuse the warp and weft threads of the resin-permeable sheet to the reinforcing fiber layer.

[0032] The reinforcing fiber sheet can be attached by, for example, applying a room-temperature curing epoxy resin to the surface of the handrail pipe 1. After the reinforcing fiber sheet is attached to the applied surface, an impregnation roller is used to promote the impregnation of the resin into the interior of the sheet, causing some of the resin to ooze out onto the surface of the sheet. Further impregnation adhesive resin is then added, and a degassing process is performed to promote further resin impregnation and to prevent air bubbles from remaining inside. Through these processes, the reinforcing fiber sheet can be impregnated and bonded to the surface of the handrail pipe 1.

[0033] The weight of the reinforcing fiber sheet is preferably 600 g / m 2 More preferably, it is 800 g / m or more. 2 That's all. The fiber weight is 1m 2 This is calculated from the number of reinforcing fiber bundles used in the reinforcing fiber sheet. By increasing the weight of the reinforcing fiber, the rigidity of the handrail pipe 1 can be effectively restored.

[0034] When the reinforcing fiber sheet is attached, each reinforcing fiber extends along the axial direction of the handrail pipe 1. In other words, the first fiber sheet 11 attached to the handrail pipe 1 presents a repair structure in which multiple reinforcing fibers are arranged along the axial direction of the handrail pipe 1.

[0035] As described above, the rigidity of the handrail pipe 1 can be restored by arranging the first fiber sheet 11 in the axial direction of the handrail pipe 1, in other words, by arranging the first fiber sheet 11 so that the orientation direction of the reinforcing fibers is along the axial direction of the handrail pipe 1.

[0036] The second fiber sheet 12 is wrapped around the first fiber sheet 11 in the circumferential direction of the handrail pipe 1. The end of the second fiber sheet 12 in the axial direction of the handrail pipe 1 may be flush with the first fiber sheet 11 or may protrude slightly beyond the first fiber sheet 11. In other words, the length of the second fiber sheet 12 in the axial direction of the handrail pipe 1 is the same as or longer than the first fiber sheet 11.

[0037] The second fiber sheet 12 uses the previously described reinforcing fiber sheet because the fiber direction needs to be bent along the circumferential direction of the handrail pipe 1. Details of the reinforcing fiber sheet will not be repeated. Furthermore, the method of impregnating and bonding the reinforcing fiber sheet is as described above, so will not be repeated. Note that when the first fiber sheet 11 and the second fiber sheet 12 are both reinforcing fiber sheets, the properties, physical properties, and basis weight of the fibers may be the same or different from each other.

[0038] The weight of the reinforcing fibers in the second fiber sheet 12 is preferably 200 g / m 2 More than 500g / m 2 or less, more preferably 200 g / m 2 More than 300g / m 2 The reasons are as follows: If the weight of the reinforcing fibers becomes too large (which can be said to be excessive repair), the amount of deflection when an impact load is applied will be small, and the handrail pipe 1 will not be able to absorb the energy of the fall, which may cause damage to areas other than the repaired area and is also undesirable from a cost perspective. If the weight of the reinforcing fibers becomes too small, the effect of suppressing cracking of the first fiber sheet 11 will not be fully realized. The weight of the fibers shall conform to JISR 7602.

[0039] When the second fiber sheet 12 is attached, each reinforcing fiber extends along the circumferential direction of the handrail pipe 1. In other words, the second fiber sheet 12 wrapped around the handrail pipe 1 presents a repair structure in which multiple reinforcing fibers are arranged along the circumferential direction of the handrail pipe 1.

[0040] By wrapping the second fiber sheet 12 around the first fiber sheet 11, a restraining effect on the first fiber sheet 11 is exerted, thereby preventing cracks from occurring in the first fiber sheet 11 when a bending load acts on the handrail pipe 1. In other words, when the first fiber sheet 11 is a strand sheet, cracks are prevented from occurring in the resin used to attach the strand sheet, and when the first fiber sheet 11 is a reinforcing fiber sheet, cracks are prevented from occurring in the resin used to impregnate and bond the reinforcing fiber sheet. Furthermore, the first fiber sheet 11 and the second fiber sheet 12 work together to more effectively restore the soundness (impact resistance) of the handrail pipe 1.

[0041] As a variant, a finishing coat may be applied over the second fiber sheet 12. This makes the surface of the second fiber sheet 12 less noticeable, making it smooth, and is preferable because it reduces the effects of sunlight, moisture, exhaust gas, etc. In this case, it is desirable to wrap a release film over the second fiber sheet 12 and peel off the release film after the adhesive resin has hardened. This improves the surface smoothness of the area where the fiber sheet 12 is wrapped.

[0042] According to this embodiment, if damage is found to the handrail pipe 1 of the inspection path, the main repair work can be completed simply by attaching the first fiber sheet 11 along the axial direction of the handrail pipe 1 and wrapping the second fiber sheet 12 around the first fiber sheet 11 along the circumferential direction of the handrail pipe 1 and impregnating and bonding them. This eliminates the need to replace long-span components, as in conventional repair work, and simplifies the repair work and reduces costs. As the fiber sheet, in addition to a continuous fiber sheet having a layer in which the reinforcing fibers are oriented in one direction, a woven fabric made of woven reinforcing fibers can also be used. However, since the amount of reinforcing fibers oriented in the desired direction is small due to the woven fabric, the amount of wrapping is large, and it is difficult to impregnate the adhesive, so this is not suitable. [Example]

[0043] Next, the present invention will be described in detail with reference to examples. A GFRP pipe was prepared, and in order to simulate damage to a handrail pipe in an inspection road, the GFRP pipe was cut in the circumferential direction using a disc sander. A first fiber sheet was attached to the cut portion X (see FIG. 3) along the axial direction of the handrail pipe, and then a second fiber sheet was wrapped around the first fiber sheet along the circumferential direction of the handrail pipe and impregnated and bonded to simulate repair. After the repair, a three-point bending test and an impact loading test were performed to evaluate the repair effect.

[0044] The anchoring lengths of the first and second fiber sheets were 200 mm on both the left and right sides of the cut point X. In Figure 3, the support points in the three-point bending test are indicated by triangles. The span of the three-point bending test was 12,000 mm. The load P was controlled by displacement control at 5 mm / min, and the maximum value of the load P was recorded as the bending load.

[0045] The impact load test was conducted based on the "Impact Load Test for Handrails" section of Test Method 440-2017, Test Method for FRP and Aluminum Alloy Inspection Roads, published in NEXCO Test Methods, Part 4, Structural-Related Test Methods (July 2020). The GFRP inspection road was fixed to a support platform, and the upper handrail pipe was cut circumferentially. Repairs were performed using the first and second fiber sheets in a manner similar to the three-point bending test. A safety harness and a dummy weight, connected to each other by a lanyard, were prepared. The safety harness was attached to the upper handrail pipe, and the dummy weight was allowed to free-fall from the height of the upper handrail pipe. For evaluation, if no breakage of the handrail pipe was observed and no damage to the inspection road was observed, the repair was rated AA, indicating extremely high repair effectiveness. If no breakage of the handrail pipe was observed but damage to the inspection road was confirmed (but the dummy weight did not fall), the repair was rated A, indicating high repair effectiveness. When the handrail pipe broke and the dummy weight fell, the repair effect was deemed low and it was rated as B. The weight of the dummy weight was 85 kg and the length of the lanyard was 1700 mm. [Table 1]

[0046] In Example 1, a strand sheet made of aramid fiber (product number: FSS-AK-120, manufactured by Nippon Steel Chemical & Material Co., Ltd., fiber basis weight 830 g / m) was used as the first fiber sheet (axial repair sheet). 2 ) was used, and a reinforced fiber sheet made of aramid fiber (product number FTS-AK-40, manufactured by Nippon Steel Chemical & Material, fiber basis weight 280 g / m) was used as the second fiber sheet (circumferential repair sheet). 2 The number of windings was one for both the first and second fiber sheets. In Example 2, the strand sheet of Example 1 was used as the first fiber sheet, and a reinforced fiber sheet (product number: FTS-AK-60, manufactured by Nippon Steel Chemical & Material Co., Ltd., fiber basis weight 415 g / m) made of aramid fiber, which has a higher fiber basis weight than the product number: FTS-AK-40 of Example 1, was used as the second fiber sheet. 2) was used. In Comparative Example 1, the strand sheet of Example 1 was used as the first fiber sheet, and no second fiber sheet was wrapped around it in the circumferential direction. Note that Reference Example 1 was a sound GFRP pipe with no cut portion X.

[0047] The results of the three-point bending test for each specimen (Reference Example 1, Examples 1 and 2, and Comparative Example 1) are shown in Figure 4. Figure 4 is a graph recording the relationship between the load P and the vertical displacement of the load point, with the vertical axis representing the load P (N) and the horizontal axis representing the amount of displacement (mm).

[0048] Comparing Examples 1 and 2 with Comparative Example 1, it was found that repairing a GFRP pipe using the first fiber sheet and the second fiber sheet improved impact resistance (see Table 1). In Example 2, the basis weight of the second fiber sheet was increased compared to Example 1. As a result, although the handrail pipe was not damaged in the impact loading test, the impact that could not be fully absorbed resulted in over-repair, causing damage to the inspection path (the handrail structure mounting base), and impact resistance was reduced (see Table 1).

[0049] In the three-point bending test, all specimens underwent compressive failure in the ultimate state. Referring to Figure 4, repaired Examples 1 and 2 and Comparative Example 1 achieved repair effects exceeding those of Reference Example 1, which was in a sound state, in terms of bending rigidity and withstand load. It was also found that Examples 1 and 2, which were reinforced in both the axial and circumferential directions, experienced a more mitigated load drop after reaching the maximum load than Comparative Example 1, which was reinforced only in the axial direction (no circumferential reinforcement). This is thought to be because cracking of the adhesive resin was suppressed by attaching the second fiber sheet in the circumferential direction and restraining the first fiber sheet. [Explanation of symbols]

[0050] 1 Handrail pipe 1a Repair area 2 Repair sheet 11 First fiber sheet 12 Second fiber sheet

Claims

1. A method for repairing a handrail pipe made of glass fiber reinforced resin installed on an inspection path, comprising: A first step of attaching a first fiber sheet containing reinforcing fibers to a position that covers at least the repair area of ​​the handrail pipe so that the orientation direction of the fibers is along the axial direction of the handrail pipe; A second step of attaching a second fiber sheet containing reinforcing fibers from above the first fiber sheet so that the orientation direction of the fibers is along the circumferential direction of the handrail pipe; A repair method comprising the steps of:

2. The first fiber sheet is a strand sheet in which rod-shaped strands formed by bundling continuous fibers made of reinforcing fibers and curing them with a resin are arranged in one direction and pulled together like a curtain, or a reinforcing fiber sheet in which reinforcing fibers are arranged in one direction, The repair method according to claim 1 , wherein the second fiber sheet is the reinforcing fiber sheet.

3. 3. The repair method according to claim 2, wherein the strands in the strand sheet are connected to each other by weft threads.

4. 4. The repair method according to claim 1, wherein the reinforcing fibers contained in the first and second fiber sheets are aramid fibers.

5. 5. The repair method according to claim 1, further comprising a third step of applying a finishing coat over the second fiber sheet.

6. A repair structure for a handrail pipe made of glass fiber reinforced resin installed on an inspection path, A first fiber sheet containing reinforcing fibers arranged so as to cover at least the repaired portion of the handrail pipe; A second fiber sheet including reinforcing fibers laminated on the first fiber sheet, The reinforcing fibers in the first fiber sheet are oriented in a direction along the axial direction of the handrail pipe, A repair structure characterized in that the reinforcing fibers in the second fiber sheet are oriented in a direction along the circumferential direction of the handrail pipe.

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