Reinforcing ring and reinforcing method

Abstract

A reinforcing ring (10), which is installed between a peripheral wall (21) forming a hole (22) open toward the ground in a concrete skeleton (20) buried in the ground and a receiving frame (32) of a lid (30) for closing the hole (22), has an outer diameter larger than an outer diameter of the peripheral wall (21).

Description

Reinforcement ring and reinforcing method

[0001] The present disclosure relates to a reinforcement ring and a reinforcement method.

[0002] Handholes are generally installed at the edge of roads. Therefore, while people may walk over them, they are not designed for vehicles to pass over them. There are cases where the width of a road is widened, but the handhole remains in place without any relocation work. In such cases, vehicles pass over the handhole. When a vehicle passes over it, it comes into contact with the top cover of the handhole, and the force from the vehicle is transmitted to the body of the handhole via the top cover. Some handhole bodies are made of only concrete without any reinforcing bars. Such unreinforced concrete bodies are heavily affected by the load when vehicles pass over them, so reinforcement is required.

[0003] Non-Patent Document 1 discloses a method of reinforcing the inner surface of a handhole body by attaching an aramid fiber sheet to the inner surface of the body.

[0004] "Handhole reinforcement technology", [online], Airec Engineering Co., Ltd., [Retrieved May 27, 2024], Internet <URL: https: / / www.airec.co.jp / products / renovation / handhole.html>

[0005] At least a portion of the space inside the handhole's frame is filled with installed objects such as cables. In order to reinforce using conventional methods, it is necessary to be able to move the installed objects, such as cables, inside the frame. Even if this condition is met, when reinforcement is performed using conventional methods, the space inside the frame is narrowed by the reinforcing members, such as sheet materials, and this narrows the space available for maintenance work.

[0006] The purpose of the present disclosure, which has been made in consideration of such circumstances, is to reduce the load on a concrete skeleton without reinforcing the interior of the skeleton.

[0007] In one embodiment, the reinforcing ring is installed between a peripheral wall of a concrete structure buried underground that forms a hole that opens toward the ground and a receiving frame for a lid that closes the hole, and has an outer diameter larger than the outer diameter of the peripheral wall.

[0008] A reinforcement method according to one embodiment includes installing at least one reinforcement ring having an outer diameter larger than the outer diameter of a peripheral wall of a concrete structure buried underground, the peripheral wall forming a hole that opens toward the ground, and a receiving frame for a lid that closes the hole.

[0009] According to the present disclosure, the load on the concrete skeleton can be reduced without reinforcing the interior of the skeleton.

[0010] 1 is a cross-sectional view showing the shape and arrangement of each member such as a reinforcing ring used in a reinforcing method according to one embodiment; 2 is a photograph of a reinforcing ring; 3 is a plan view of a reinforcing ring; 4 is a cross-sectional view of a reinforcing ring taken along the line A-A; 5 is a diagram showing an analysis result using a comparative example; 6 is a diagram showing an analysis result using an example; 7 is a table of physical properties; 8 is a table of constraint conditions; 9 is a flowchart of a reinforcing method; 10 is a diagram showing the procedure of a reinforcing method; 11 is a diagram showing the procedure of a reinforcing method; 12 is a table comparing a construction method of an example with a construction method of a comparative example.

[0011] An embodiment will be described below with reference to the drawings.

[0012] In each drawing, the same or corresponding parts are denoted by the same reference numerals. In the description of this embodiment, the description of the same or corresponding parts will be omitted or simplified as appropriate.

[0013] The shape and arrangement of each member used in the reinforcing method according to this embodiment will be described with reference to FIG.

[0014] At least one reinforcing ring 10 is installed between a peripheral wall 21 of a concrete body 20 buried underground, which forms a hole 22 open toward the ground, and a receiving frame 32 of a lid 30 for closing the hole 22. The reinforcing ring 10 has an outer diameter larger than the outer diameter of the peripheral wall 21. The reinforcing ring 10 has an outer diameter that is, for example, +10 cm to +15 cm larger than the outer diameter of the peripheral wall 21. In this embodiment, the reinforcing ring 10 has an inner diameter equal to the inner diameter of the peripheral wall 21, but may have an inner diameter different from the inner diameter of the peripheral wall 21. The reinforcing ring 10 is formed of high-strength concrete. The reinforcing ring 10 preferably has a compressive strength of 180 N / mm ２ Concrete with an elastic modulus of 50,000 N / mm or more ２ The concrete is formed from the above. The unit of compressive strength may be MPa. For example, the compressive strength is 180 N / mm ２ is equivalent to a compressive strength of 180 MPa.

[0015] In this embodiment, the concrete body 20 is an unreinforced concrete body for a handhole, but it may also be the body of another type of underground structure, such as the body of a manhole.

[0016] In this embodiment, mortar 40 is installed around the peripheral wall 21. The reinforcing ring 10 is installed on the peripheral wall 21 and the mortar 40. In this embodiment, the mortar 40 has an outer diameter equal to the outer diameter of the reinforcing ring 10, but may have an outer diameter different from the outer diameter of the reinforcing ring 10.

[0017] In this embodiment, a steel plate 50 is further placed on the reinforcing ring 10. The lid 30 is placed on the steel plate 50. The steel plate 50 has a ring shape similar to the reinforcing ring 10. In this embodiment, the steel plate 50 has an outer diameter equal to the outer diameter of the reinforcing ring 10, but may have an outer diameter different from the outer diameter of the reinforcing ring 10. In this embodiment, the steel plate 50 has an inner diameter equal to the inner diameter of the reinforcing ring 10, but may have an inner diameter different from the inner diameter of the reinforcing ring 10. The steel plate 50 is formed of, for example, SS400.

[0018] The lid 30 has a receiving frame 32 and an upper lid 31 exposed above ground. In this embodiment, the lid 30 has an outer diameter equal to the outer diameter of the peripheral wall 21, but may have an outer diameter different from the outer diameter of the peripheral wall 21. The lid 30 is formed of, for example, iron.

[0019] In this embodiment, a road is constructed on the ground 60 in which a concrete skeleton 20 is buried. Therefore, the concrete skeleton 20 does not contain reinforcing bars, and when a vehicle passes over it, the load is affected. However, by using a reinforcing ring 10 that is larger and stronger than the concrete skeleton 20, the load can be dispersed and the impact on the concrete skeleton 20 can be reduced. According to this embodiment, since the reinforcing ring 10 has high strength, deflection under load is reduced, and the load generated in the reinforcing ring 10 itself can be dispersed. As a result, reinforcement that distributes the load on the concrete skeleton 20 is possible, and the existing concrete skeleton 20 can be used for a long period of time.

[0020] The space inside the concrete skeleton 20 is filled with installed objects such as cables, making it difficult to reinforce from the inside, but according to this embodiment, even in such a situation, it is possible to reinforce from the outside using the reinforcing ring 10. In other words, it is possible to reinforce equipment that cannot be reinforced from the inside from the outside, ensuring the safety of the equipment while eliminating the need for renovation and establishing an inexpensive measure.

[0021] As described above, according to this embodiment, in the method for reinforcing a plain concrete skeleton, a neck ring that is larger than the target skeleton and has high strength is installed between the upper part of the skeleton and the lower part of the top cover, so that the load from above the top cover can be dispersed. Therefore, the load on the skeleton can be reduced without reinforcing the inside of the skeleton.

[0022] 2 to 4 show specific examples of the reinforcing ring 10. Fig. 4 shows a cross section of the reinforcing ring 10 taken along line AA in Fig. 3.

[0023] In this example, the length, width, and height of the reinforcing ring 10 are L, W, and H, respectively, where L = 1200 cm, W = 800 cm, and H = 70 cm. The reinforcing ring 10 is rectangular and has a through hole 11 that is generally rectangular in plan view. In the length direction of the reinforcing ring 10, if the dimension from one end of the reinforcing ring 10 to the edge of the through hole 11 and the dimension from the other end of the reinforcing ring 10 to the edge of the through hole 11 are both L1, then L1 = 200 cm. Therefore, if the length of the through hole 11 is L2, then L2 = 800 cm. In the width direction of the reinforcing ring 10, if the dimension from one end of the reinforcing ring 10 to the edge of the through hole 11 and the dimension from the other end of the reinforcing ring 10 to the edge of the through hole 11 are both W1, then W1 = 200 cm. Therefore, if the length of the through hole 11 is W2, then W2 = 400 cm.

[0024] The reinforcing ring 10 further has fixing bolt holes 12 for connecting the reinforcing ring 10 to the steel plate 50. When there are two or more reinforcing rings 10, the reinforcing rings 10 can be stacked and can be connected and integrated through the fixing bolt holes 12. The fixing bolt holes 12 are provided at four locations corresponding to the four corners of the reinforcing ring 10, two locations on one side of the through hole 11 and two locations on the other side of the through hole 11 at the center of the length of the reinforcing ring 10, and two locations on one side of the through hole 11 and two locations on the other side of the through hole 11 at the center of the width of the reinforcing ring 10, for a total of 12 locations. If the dimension from the edge of the reinforcing ring 10 to the center of the fixing bolt holes 12 at the corners of the reinforcing ring 10 in the length direction is L3, then L3 = 100 cm. If the dimension from the edge of the reinforcing ring 10 to the center of the fixing bolt holes 12 at the corners of the reinforcing ring 10 in the width direction is W3, then W3 = 100 cm.

[0025] The reinforcing ring 10 further has two joining grooves 13, including a groove that runs around the outer periphery of the reinforcing ring 10 and between the fixing bolt holes 12, and a groove that runs around the inner periphery of the reinforcing ring 10 and between the fixing bolt holes 12. The reinforcing ring 10 also contains a reinforcing bar 14, as shown by the dashed line in Figure 3.

[0026] A specific example of the reinforcing ring 10 as described above is used as an example, and a ring formed of concrete with a compressive strength of approximately 26.5 MPa, similar to a conventional neck ring, instead of the reinforcing ring 10 is used as a comparison example. The results of analysis using each example are shown in Figures 5 and 6.

[0027] As shown in FIG. 5 , in the comparative example, due to the low material strength, when subjected to a vehicle load of 80 kN, the ring bends and the concrete skeleton 20 is also pulled. As a result, not only does the tensile stress generated in the ring itself exceed the allowable value, but the tensile stress generated in the concrete skeleton 20 also exceeds the allowable value. On the other hand, as shown in FIG. 6 , in the example, the allowable value is increased by using a high-strength material, making it possible to withstand loads that the concrete of the comparative example could not withstand. In other words, even when subjected to a vehicle load of 80 kN, the reinforcing ring 10 does not bend and the concrete skeleton 20 is not pulled. As a result, not only does the tensile stress generated in the reinforcing ring 10 itself remain within the allowable value, but the tensile stress generated in the concrete skeleton 20 also remains within the allowable value.

[0028] As described above, when concrete of the same strength as that of a conventional neck ring is used, the range in which the ring deflects due to the influence of the vehicle load is wide, and the concrete skeleton 20 is easily pulled when a vehicle passes. In contrast, when high-strength concrete is used, the range in which the reinforcing ring 10 deflects due to the influence of the vehicle load is narrow, and the concrete skeleton 20 is less likely to be pulled when a vehicle passes.

[0029] The reinforcement effect of the embodiment was verified using the shape and arrangement shown in FIG. 1, the physical properties shown in FIG. 7, and the constraints shown in FIG. 8, and it was confirmed that the desired reinforcement effect could be obtained. The reinforcing ring 10 was configured by stacking two rings. In FIG. 7, "HH" refers to a handhole. In FIG. 8, the friction coefficient for "with friction" is, for example, 0.5, but other values ​​such as 0.4 or 0.6 may also be used. In this verification, it was examined whether the load acting on the concrete skeleton 20 is dispersed. The results of distributing the load were analyzed using FEM to confirm the effectiveness of the reinforcement method. "FEM" is an abbreviation for finite element method.

[0030] The reinforcing method according to this embodiment will be described with reference to FIGS.

[0031] The reinforcing method according to this embodiment includes steps S1 to S5 shown in FIG.

[0032] As shown in Fig. 10, step S1 is a step of removing the cover 30, which is an existing component. In step S1, if an existing ring 70 is also installed as another existing component, the existing ring 70 is also removed. The existing ring 70 is, for example, a neck ring made of concrete with a compressive strength of about 26.5 MPa, as in the comparative example described above.

[0033] 10, S2 is a step of placing mortar 40 around the periphery of the peripheral wall 21 of the concrete skeleton 20. In S2, before placing the mortar 40, excavation is also performed around the periphery of the peripheral wall 21 of the concrete skeleton 20.

[0034] 11 , S3 is a step of installing at least one reinforcing ring 10 between the peripheral wall 21 of the concrete body 20 and the receiving frame 32 of the lid 30. In S3, the reinforcing ring 10 is installed on the peripheral wall 21 of the concrete body 20 and the mortar 40. If there are two or more reinforcing rings 10, one or more other reinforcing rings 10 are installed on top of the reinforcing ring 10 installed on the peripheral wall 21 of the concrete body 20 and the mortar 40.

[0035] S4 is a step of placing a steel plate 50 on at least one reinforcing ring 10, as shown in Fig. 11. When the number of reinforcing rings 10 is two or more, the steel plate 50 is placed on the reinforcing ring 10 placed at the top.

[0036] S5 is a step of placing the lid 30 on the steel plate 50 as shown in FIG.

[0037] By following the procedure described above, it is possible to distribute the load on the steel cover by using a high-strength ring for an underground concrete box. The reinforcement method according to this embodiment requires less work inside the structure, such as relocating cables and other installed objects inside the structure, compared to conventional reinforcement methods, making it simpler and expected to reduce costs.

[0038] The above-described procedure is used as an example, and the method disclosed in Non-Patent Document 1 is used as a comparative example. The work performed by each example method and the time required for each example method are shown in FIG. 12.

[0039] 12, in the comparative example, it takes about three days in total to protect the contents inside, prepare the base, install the reinforcing members, and restore the container. On the other hand, in the example, it takes about one day in total to remove the existing members, prepare for the installation of the reinforcing members, install the reinforcing members, restore the container, and install the lid.

[0040] As described above, the construction method according to this embodiment can be carried out in a shorter time than conventional construction methods. Since there are no materials that require on-site adjustment, and the main work is installation, efficiency is improved. Furthermore, there is no need to deal with internal contents, such as cable protection, which further reduces construction time.

[0041] As described above, according to this embodiment, it is possible to easily reinforce a plain concrete skeleton installed in a location that is subject to the influence of vehicle loads, when there is space outside the skeleton. This allows the equipment to be used for a long period of time, thereby achieving economy.

[0042] The present disclosure is not limited to the above-described embodiments, and modifications are possible within the scope of the present disclosure.

[0043] REFERENCE SIGNS LIST 10 Reinforcement ring 11 Through hole 12 Fixing bolt hole 13 Joint groove 14 Reinforcement bar 20 Concrete body 21 Peripheral wall 22 Hole 30 Lid 31 Upper lid 32 Receiving frame 40 Mortar 50 Steel plate 60 Ground 70 Existing ring

Claims

1. A reinforcing ring that is installed between a peripheral wall that forms a hole that opens toward the ground in a concrete structure buried underground and a receiving frame for a cover that closes the hole, the reinforcing ring having an outer diameter larger than the outer diameter of the peripheral wall.

2. Compression strength 180N / mm ２ Concrete with an elastic modulus of 50,000 N / mm or more ２ 2. The reinforcing ring of claim 1, formed from the above concrete.

3. A reinforcement method comprising installing at least one reinforcing ring having an outer diameter larger than the outer diameter of a peripheral wall of a concrete structure buried underground, between the peripheral wall forming a hole that opens toward the ground and a receiving frame for a cover for closing the hole.

4. The reinforcing method according to claim 3, comprising: removing the lid; placing mortar around the peripheral wall; and, as the step of placing the at least one reinforcing ring, placing the at least one reinforcing ring on the peripheral wall and the mortar; placing a steel plate on the at least one reinforcing ring; and placing the lid on the steel plate.

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