JP7843643B2 - Optical fiber laying method - Google Patents

Description

This invention relates to a method for laying optical fibers.

Conventionally, a technique is known for measuring the strain and temperature distribution of a concrete structure by irradiating it with laser pulses and observing and analyzing the scattered light (see, for example, Patent Document 1 below). In the construction of this type of concrete structure, optical fiber cables are pre-wired within the concrete formwork, and the concrete is poured, thereby integrating the optical fiber cables with the concrete structure.

Patent No. 4008623

However, because fiber optic cables are thin, brittle, and susceptible to damage from contact, they are prone to breakage due to contact with rebar during rebar assembly within formwork, exposure to concrete pouring pressure (including contact with concrete aggregate), or contact with vibrators during compaction. To avoid such damage to fiber optic cables caused by concrete pouring, it is conceivable to install the fiber optic cables on the surface of the concrete structure after its construction. However, even in this case, there is a risk of breakage due to the fiber optic cables on the concrete structure surface being stepped on by workers or coming into contact with materials.

In view of these problems, the present invention aims to provide an optical fiber laying method that allows for easy laying of optical fibers within a structure and reduces the possibility of optical fiber breakage.

The gist of this invention is as follows: [1] to [10].

[1] A method for laying optical fibers near the surface of a structure, comprising: a structure construction step of constructing the structure by installing a groove-forming member on the inner surface of a concrete formwork and pouring concrete, thereby forming optical fiber grooves on the surface as the remnants of the removal of the groove-forming member; and an optical fiber installation step of installing the optical fibers in the optical fiber grooves, filling them with a hardening material and allowing it to harden, thereby integrating the structure and the optical fibers via the hardening material.

[2] The optical fiber laying method according to [1], wherein in the frame construction step, the groove-forming member is installed as a chamfer on the inner surface of the concrete formwork and concrete is poured.

[3] The optical fiber laying method according to [1], wherein in the frame construction step, the frame is constructed with the groove-forming member made of a thermoplastic material embedded in the surface, and then the groove-forming member is heated and altered to remove it from the frame, thereby forming the optical fiber groove as the removal mark.

[4] A method for laying optical fibers near the surface of a structure, comprising: a structure construction step of constructing the structure by installing an optical fiber encapsulating member on the inner surface of a concrete formwork and pouring concrete, thereby constructing the structure in which the optical fiber encapsulating member is embedded on the surface; and an optical fiber installation step of inserting the optical fiber into the optical fiber encapsulating member on the surface of the structure, thereby integrating the structure and the optical fiber via the optical fiber encapsulating member.

[5] The optical fiber laying method according to [4], wherein in the optical fiber installation step, the optical fiber is placed in the optical fiber groove provided in the optical fiber encapsulating member and opening on the surface side of the frame, and a curable material is filled and cured, thereby integrating the frame and the optical fiber via the curable material and the optical fiber encapsulating member.

[6] The optical fiber installation method according to [4], wherein in the optical fiber installation step, the optical fiber is inserted into a notch cut into the surface side of the frame, which is provided in the optical fiber encapsulating member made of thermoplastic resin, and then the optical fiber encapsulating member is heated to fuse and close the notch, thereby integrating the frame and the optical fiber via the optical fiber encapsulating member.

[7] The optical fiber laying method according to [4], wherein the optical fiber encapsulating member comprises a tubular body and granular material made of thermoplastic resin filled inside the tubular body, and in the optical fiber installation step, the optical fiber is inserted into the gaps between the granular material through an optical fiber insertion port provided in the tubular body and opening on the surface side of the frame, and then the optical fiber encapsulating member is heated to fuse the granular material together and integrate them, thereby integrating the frame and the optical fiber via the optical fiber encapsulating member.

[8] A method for laying optical fibers near the surface of a structure, comprising: a structure construction step of constructing the structure having optical fiber grooves formed on its surface; and an optical fiber installation step of installing the optical fibers in the optical fiber grooves and integrating the structure and the optical fibers.

[9] The optical fiber laying method according to [8], wherein in the frame construction step, a groove-forming member is installed on the inner surface of the concrete formwork and concrete is poured, and the optical fiber groove is formed on the surface of the frame as the trace of the removal of the groove-forming member.

[10] The optical fiber laying method according to [8], wherein in the frame construction step, an optical fiber encapsulating member having an optical fiber groove opening on the surface side of the frame is placed on the inner surface of a concrete formwork, concrete is poured, and the frame is constructed with the optical fiber encapsulating member embedded in the surface.

According to the present invention, it is possible to provide an optical fiber laying method that allows for easy installation of optical fibers into a structure and reduces the possibility of optical fiber breakage.

(a) is a cross-sectional view showing the formwork in the optical fiber laying method of the first embodiment, and (b) is a cross-sectional view taken perpendicular to it. (a) is a front view of the concrete structure constructed in the first embodiment, (b) is a perspective view thereof, and (c) and (d) are enlarged cross-sectional views showing the main parts thereof. (a) to (d) are cross-sectional views showing the chamfer strips used in the optical fiber laying method of the first embodiment, and (e) is a perspective view of the mesh sheet material. (a) is a front view showing the existing concrete structure and the new formwork, (b) is a section view of the IVb-IVb section thereof, and (c) is a front view showing the concrete structure according to the modified example. (a) is a cross-sectional view showing the formwork in the optical fiber laying method of the second embodiment, and (b) is a cross-sectional view taken perpendicular to it. (a) to (c) are enlarged cross-sectional views showing the main parts of the concrete structure in the optical fiber laying method of the second embodiment, and (d) to (f) are cross-sectional views showing modified examples thereof. (a) is a cross-sectional view showing the formwork in the optical fiber laying method of the third embodiment, and (b) is a cross-sectional view taken perpendicular to it. (a) to (b) are enlarged cross-sectional views showing the main part of the concrete structure in the optical fiber laying method of the third embodiment, and (c) to (d) are cross-sectional views showing modified examples thereof. (a) is a cross-sectional view showing the formwork in the optical fiber laying method of the fourth embodiment, and (b) is a cross-sectional view taken perpendicular to it. (a) to (c) are enlarged cross-sectional views showing the main part of the concrete structure in the optical fiber laying method of the fourth embodiment, and (d) to (e) are cross-sectional views showing modified examples thereof. (a) is a cross-sectional view showing the formwork in the optical fiber laying method of the fifth embodiment, and (b) is a cross-sectional view taken perpendicular to it. Figures (a) to (c) are enlarged cross-sectional views showing the main parts of the concrete structure in the optical fiber laying method of the fifth embodiment.

The following describes in detail each embodiment of the optical fiber laying method according to the present invention with reference to the drawings. In each embodiment, identical or equivalent components are denoted by the same reference numerals in the drawings, and redundant descriptions are omitted.

The optical fiber laying methods of each embodiment can be applied to various concrete structures such as surface members, column members, and beam members in various reinforced concrete (RC) structures such as box culverts, bridge piers, and sluice gates. The optical fiber laying methods of each embodiment involve laying an optical fiber cable 11 near the surface 1a of a reinforced concrete structure 1. For example, the optical fiber cable 11 is embedded in the concrete cover portion of the concrete structure 1. The optical fiber cable 11 in each embodiment may be, for example, an optical fiber core with a diameter of 0.9 mm, or it may be an optical fiber cable in the narrow sense that includes multiple bundled optical fiber cores.

In each embodiment of the optical fiber laying method, a measuring device (not shown) is connected to the end of the optical fiber cable 11 laid in the concrete structure 1. This measuring device emits laser pulse light onto the optical fiber strands of the optical fiber cable 11 and receives scattered light returning from various positions along the longitudinal direction of the optical fiber strands. Based on the principle that the intensity and wavelength of the scattered light depend on the strain and temperature changes applied to the optical fiber strands, the measuring device acquires the strain and temperature at each position along the longitudinal direction of the optical fiber cable 11. Consequently, the longitudinal strain distribution and temperature distribution in the concrete structure 1 are obtained.

[First Embodiment]
A method for laying optical fibers according to the first embodiment will now be described. This laying method comprises a frame construction step and an optical fiber installation step, which will be described below.

(frame construction process)
In the structural construction process of this embodiment, as shown in Figures 1(a) and 1(b), concrete formwork 3 for constructing the concrete structure 1 is prepared. A chamfer strip 5 (groove-forming member) is attached to the inner surface of the formwork 3 along the planned laying position of the optical fiber cable 11. Reinforcing bars 7 are also placed inside the formwork 3. After that, concrete is poured into the formwork 3. The concrete pouring is carried out in the same procedure as for the construction of a normal concrete structure, and the concrete is cured. After that, the formwork 3 is removed in the same procedure as for the construction of a normal concrete structure. At this time, the chamfer strip 5 is also removed together with the formwork 3. Alternatively, after the formwork 3 is removed, the chamfer strip 5 may be embedded on the surface 1a of the concrete structure 1, and then the chamfer strip 5 may be removed from the concrete structure 1.

As a result, the concrete structure 1 is constructed as shown in Figures 2(a) and 2(b). On the surface 1a of the concrete structure 1, a groove 9 for optical fibers is formed as a result of the removal of the chamfer strip 5. The optical fiber groove 9 extends, for example, in a straight line along the planned laying position of the optical fiber cable 11.

(Optical fiber installation process)
In the optical fiber installation process of this embodiment, as shown in Figure 2(c), the optical fiber cable 11 is installed in the optical fiber groove 9. Furthermore, as shown in Figure 2(d), a curable material is filled into the optical fiber groove 9, and the curable material hardens with the optical fiber cable 11 embedded in it. Examples of curable materials used here include cement mortar, resin mortar, polymer cement mortar, and adhesives. As a result, the concrete structure 1 and the optical fiber cable 11 are integrated via the embedded layer 13 made of the hardened curable material. The optical fiber cable 11 is laid embedded at a position slightly deeper than the surface 1a of the concrete structure 1.

(Menki)
The chamfer strip 5 used in the optical fiber laying method of this embodiment will now be described. As the chamfer strip 5 used here, for example, one with an isosceles triangle cross-section is used, as shown in Figure 3(a). With this chamfer strip 5, the optical fiber groove 9 is formed as a V-groove with an isosceles triangle cross-section. Note that the shape of the chamfer strip 5 is not limited to an isosceles triangle cross-section; any shape that can be removed from the surface 1a of the hardened concrete structure 1 is acceptable. That is, the cross-sectional shape of the chamfer strip 5 should be such that it becomes narrower as it goes deeper from the surface 1a of the concrete structure 1. As long as this condition is satisfied, the cross-sectional shape of the chamfer strip 5 may be a trapezoid, as shown in Figure 3(b), or a semicircle. Examples of materials for the chamfer strip 5 include wood, polystyrene foam, rubber, resin, metal, etc. The chamfer strip 5 is installed at a height that does not reach the position of the reinforcing bars 7, for example. In this case, the depth of the optical fiber groove 9 formed by the chamfer strip 5 is smaller than the concrete cover thickness.

Furthermore, in order to improve the integrity between the concrete structure 1 and the embedded layer 13, the surface of the chamfer strip 5 (the surface in contact with the concrete) may be made uneven in order to form irregularities on the inner surface of the optical fiber groove 9. Alternatively, as shown in Figures 3(c) and 3(d), an uneven sheet 15 may be adhered to and fixed to the surface of the chamfer strip 5. For example, a corrugated sheet or a fiber mesh material can be used as the uneven sheet 15. In this case, it is conceivable that the irregularities may catch and make it difficult to remove the chamfer strip 5 and the uneven sheet 15 when removing them from the concrete structure 1. As a countermeasure, the uneven sheet 15 and the chamfer strip 5 may be made separable. In this case, first the chamfer strip 5 is removed from the concrete structure 1, and then the remaining uneven sheet 15 is removed by peeling it off from the inner surface of the optical fiber groove 9. As a specific configuration for separating the textured sheet 15 from the molding strip 5, for example, the textured sheet 15 may be temporarily fixed to the molding strip 5 using an adhesive with weak adhesive strength.

Furthermore, the optical fiber groove 9 formed on the surface 1a of the concrete structure 1 is preferably as small in cross-section as possible, from the viewpoint of minimizing the impact on the structural performance and durability of the optical fiber cable 11. Therefore, the optical fiber groove 9 is formed with the smallest possible cross-section while still being able to accommodate the optical fiber cable 11 and sufficiently filling it with a hardening material without any voids. The size of the chamfer strip 5 is determined in accordance with the size of the optical fiber groove 9.

In the above description, an example was given in which a chamfer strip 5 extending linearly in one direction is installed on the inner surface of the formwork 3. However, instead of the chamfer strip 5, a mesh sheet material 19 with a grid-like pattern of raised ridges 17 may be installed on the inner surface of the formwork 3, as shown in Figure 3(e). In this case, optical fiber grooves 9 are formed in a grid pattern on the surface 1a of the concrete structure 1, corresponding to each raised ridge 17, and optical fiber cables 11 extending in both vertical and horizontal directions can be embedded near the surface 1a of the concrete structure 1.

The effects and advantages of the optical fiber laying method of this embodiment will now be explained. As described above, the optical fiber laying method of this embodiment is an optical fiber laying method for laying an optical fiber cable 11 near the surface 1a of a concrete structure 1. It comprises a structure construction step in which a groove-forming member (chamfer 5) is installed on the inner surface of a concrete formwork 3, concrete is poured, and an optical fiber groove 9 is formed on the surface 1a as the trace of the removal of the chamfer 5, thereby constructing a concrete structure 1; and an optical fiber installation step in which an optical fiber cable 11 is placed in the optical fiber groove 9, a hardening material is filled and hardened, and the concrete structure 1 and the optical fiber cable 11 are integrated via the hardening material. Furthermore, in the structure construction step, the groove-forming member is installed on the inner surface of the concrete formwork 3 as a chamfer, and concrete is poured.

Furthermore, the optical fiber laying method of this embodiment is an optical fiber laying method for laying an optical fiber cable 11 near the surface 1a of a concrete structure 1, and comprises a structure construction step of constructing a concrete structure 1 in which an optical fiber groove 9 is formed on the surface 1a, and an optical fiber installation step of installing the optical fiber cable 11 in the optical fiber groove 9 and integrating the concrete structure 1 and the optical fiber cable 11. In the structure construction step, a groove forming member (chamfer 5) is installed on the inner surface of the concrete formwork 3 and concrete is poured, so that the optical fiber groove 9 is formed on the surface 1a of the concrete structure 1 as the trace of the removal of the groove forming member.

According to this embodiment of the optical fiber laying method, the optical fiber cable 11 can be laid near the surface 1a of the concrete structure 1 after the concrete structure 1 has been completed. That is, it is not necessary to pour concrete with the optical fiber cable 11 already installed in the formwork 3. This avoids the optical fiber cable 11 coming into contact with reinforcing bars during rebar assembly in the formwork 3, being subjected to pouring pressure (including contact with concrete aggregate) during concrete pouring, or coming into contact with a vibrator for compaction. Furthermore, since the optical fiber cable 11 is embedded inside the concrete structure 1 at a position slightly deeper than the surface 1a of the concrete structure 1, the possibility of disconnection due to being stepped on by workers or coming into contact with materials is low. Therefore, according to this embodiment of the optical fiber laying method, the possibility of disconnection of the optical fiber cable 11 when laying it in the concrete structure 1 is reduced.

Furthermore, when concrete is poured with the optical fiber cable 11 installed inside the formwork 3, the portion of the optical fiber cable 11 that penetrates the formwork 3 and is pulled out is easily damaged during the demolding process. This requires extra effort to protect this portion, and the formwork 3 must be carefully removed during the demolding process, resulting in a significant workload. In contrast, the optical fiber laying method of this embodiment reduces the aforementioned workload.

Furthermore, since the optical fiber cable 11 is embedded inside the concrete structure 1, it offers superior long-term durability compared to a method where the optical fiber cable 11 is installed on the surface 1a of the concrete structure. That is, for example, if the optical fiber cable 11 were bonded to the surface 1a of the concrete structure 1, the adhesive would be more easily exposed to ultraviolet light and water compared to when it is embedded inside the concrete structure 1. While the optical fiber cable 11 itself has high durability, if the adhesive deteriorates due to long-term exposure to ultraviolet light and water, the integration between the optical fiber cable 11 and the concrete structure 1 may decrease, potentially leading to a decline in measurement performance. Also, if the optical fiber cable 11 is on the surface 1a of the concrete structure 1, the risk of damage from flying objects is higher compared to when it is embedded inside the concrete structure 1.

In contrast, according to the optical fiber laying method of this embodiment, the optical fiber cable 11 is embedded inside the concrete structure 1 via the embedding layer 13. Therefore, the joint between the optical fiber cable 11 and the embedding layer 13 is less likely to be exposed to ultraviolet light, water, etc., and an improvement in the durability of the joint can be expected. Consequently, the deterioration of the integrity between the optical fiber cable 11 and the concrete structure 1 is suppressed, and the deterioration of measurement performance due to changes over time is suppressed. Furthermore, since the optical fiber cable 11 is embedded and protected inside the concrete structure 1, the possibility of damage to the optical fiber cable 11 due to contact with flying objects, etc., is also reduced. Thus, according to the optical fiber laying method of this embodiment, a superior optical fiber laying structure is obtained in terms of long-term durability compared to a method in which the optical fiber cable 11 is installed on the surface 1a of the concrete structure.

In this case, to lay the optical fiber cable 11 at a position slightly deeper than the surface 1a of the concrete structure 1, it is conceivable, for example, to cut a groove in the surface 1a of the concrete structure 1 with a machine and bury the optical fiber cable 11 there. However, cutting the concrete structure 1 is labor-intensive and impractical. Compared to such a method, the optical fiber laying method of this embodiment allows for the laying of the optical fiber cable 11 in a simpler and more rational manner.

Furthermore, when the concrete structure 1 is constructed in multiple blocks connected in the direction of the optical fiber cable 11's extension, and each block is constructed separately, it is possible to install the optical fiber cable 11 for each block all at once after the multiple blocks of the concrete structure 1 have been constructed. Such a single-block installation method can improve construction efficiency and shorten the construction period.

Furthermore, when the concrete structure 1 is divided into multiple blocks and constructed block by block as described above, the methods shown in Figures 4(a) and 4(b) may be adopted in the structure construction process. Figures 4(a) and 4(b) show the formwork 3 and chamfer strips 5, etc., when joining a new block of concrete structure 1 to a completed block of concrete structure 1. Figure 4(a) is a front view showing the formwork 3 and chamfer strips 5, etc., as seen from a direction perpendicular to the surface 1a of the concrete structure 1, and Figure 4(b) is a cross-sectional view taken along the line IVb-IVb.

As shown in Figures 4(a) and 4(b), the formwork 3 is assembled to be continuous with the existing concrete structure 1, and as described above, the chamfer strips 5 are attached to the inner surface of the formwork 3. Here, the chamfer strips 5 are provided to a length that extends beyond the formwork 3 towards the existing concrete structure 1, and this protruding portion is inserted into the optical fiber groove 9 of the existing concrete structure 1. Concrete is then poured into the formwork 3 from this state, constructing a new block of concrete structure 1. By repeating the construction of concrete structures 1 in this manner, the optical fiber grooves 9 are formed to be precisely aligned in a straight line across multiple blocks of concrete structure 1, and as a result, the optical fiber cables 11 can be precisely installed in a straight line across each block of concrete structure 1.

Furthermore, when installing multiple pre-constructed concrete structures 1 in the direction of the optical fiber cable 11's extension, the structure shown in Figure 4(c) may be adopted. That is, as shown in Figure 4(c), the optical fiber groove 9 formed in each concrete structure 1 may have widened sections 9a at both ends, which are flared. This structure allows positional errors in the optical fiber groove 9 in each block and installation errors in the concrete structure 1 in each block to be absorbed by the widened sections 9a, ensuring that the optical fiber cable 11 is reliably and continuously installed within the optical fiber groove 9 across multiple blocks.

[Second Embodiment]
Next, a method for laying optical fibers according to the second embodiment will be described. This laying method comprises a frame construction step and an optical fiber installation step, which will be described below.

(frame construction process)
In the structural construction process of this embodiment, as shown in Figures 5(a) and 5(b), instead of the chamfer strip 5 in the first embodiment, a groove-forming member 21 made of thermoplastic resin is attached to the inner surface of the formwork 3 along the planned laying position of the optical fiber cable 11. Subsequently, reinforcement, formwork installation, concrete pouring and curing, and demolding are carried out in the same manner as in the structural construction process of the first embodiment, and the concrete structure 1 is completed. As shown in Figure 6(a), the groove-forming member 21 is left embedded in the surface 1a of the concrete structure 1.

The groove-forming member 21 will now be described. The cross-sectional shape of the groove-forming member 21 is such that it does not easily detach from the surface 1a of the concrete structure 1. For example, in the examples shown in Figures 5 and 6(a), the cross-sectional shape of the groove-forming member 21 is a combination of a rectangle located close to the surface 1a of the concrete structure 1 and a wider circle connected to the rectangle at a position further from the surface 1a of the concrete structure 1. Furthermore, in order to improve the integration between the concrete structure 1 and the embedded layer 13 described later, irregularities may be formed on the surface of the groove-forming member 21 (the surface in contact with the concrete) to form irregularities on the inner surface of the optical fiber groove 9. For this formation of irregularities, an irregularly shaped sheet 15 (Figures 3(c) and 3(d)), similar to that in the first embodiment, may be adhered and fixed to the surface of the groove-forming member 21.

If the melting point of the groove-forming member 21 is too low, the groove-forming member 21 may soften and deform due to the heat generated when the concrete poured into the formwork 3 hardens. Therefore, it is necessary to appropriately select the material of the groove-forming member 21 to prevent such an event from occurring. Examples of thermoplastic resins for the groove-forming member 21 include polyurethane resin, which has a low melting point (approximately 60-80°C).

As described above, after the concrete structure 1 is constructed with the groove-forming member 21 embedded in the surface 1a, the groove-forming member 21 on the surface 1a is heated. As previously mentioned, the groove-forming member 21 is made of thermoplastic resin and melts when heated, so the groove-forming member 21 liquefies and is removed, for example, by being scraped out of the optical fiber groove 9 in the concrete structure 1. Alternatively, the groove-forming member 21 may be removed by being dragged out of the concrete structure 1 while it is softened by heating. After the groove-forming member 21 is removed, the optical fiber groove 9 is formed on the surface 1a of the concrete structure 1 as the trace of the removal of the groove-forming member 21, as shown in Figure 6(b). As for the method of heating the groove-forming member 21, for example, a heat gun or embossing heater may be used to blow hot air onto the groove-forming member 21, or a soldering iron may be applied to the groove-forming member 21 to heat it. Furthermore, the heating temperature of the groove-forming member 21 should be appropriately set according to the material properties of the groove-forming member 21 to suit the purpose of the frame construction process in this embodiment.

As a result, a concrete structure 1 is constructed with optical fiber grooves 9 formed on its surface 1a as the remnants of the removed groove-forming member 21. The optical fiber grooves 9 appearing on the surface 1a of the concrete structure 1 extend, for example, in a straight line along the planned laying location of the optical fiber cable 11.

(Optical fiber installation process)
The optical fiber installation process in this embodiment is performed in the same manner as the optical fiber installation process in the first embodiment. As a result, as shown in Figure 6(c), the concrete structure 1 and the optical fiber cable 11 are integrated via an embedded layer 13 made of a hardened curable material. The optical fiber cable 11 is laid embedded in a position slightly deeper than the surface 1a of the concrete structure 1.

The shape of the groove-forming member 21 is not limited to the examples in Figures 5 and 6(a), as long as it has a cross-sectional shape that prevents it from easily coming loose from the surface 1a of the concrete structure 1. For example, the cross-sectional shape of the groove-forming member 21 may be a trapezoidal shape, as shown in Figure 6(d), where it widens as it goes deeper from the surface 1a of the concrete structure 1. Alternatively, the cross-sectional shape of the groove-forming member 21 may be approximately circular, as shown in Figure 6(e).

In the above description, an example was given where the groove-forming member 21 liquefies or softens upon heating. However, the groove-forming member 21 may also be heat-shrinkable (have the property of shrinking upon heating). In this case, by heating and shrinking the groove-forming member 21, the shrunk groove-forming member 21 can be easily pulled out and removed from within the optical fiber groove 9 of the concrete structure 1. Examples of materials for such heat-shrinkable groove-forming member 21 include, for example, heat-shrinkable tubing used for insulation and protection of electric wires and components. This type of heat-shrinkable tubing mainly uses thermoplastic resins such as polyolefins, fluoropolymers, and thermoplastic elastomers as raw materials.

Furthermore, as shown in Figure 6(f), the groove-forming member 21 may have a low-melting-point portion 21a with a relatively low melting point, and a high-melting-point portion 21b located in the outermost layer, enclosing the low-melting-point portion 21a and having a relatively high melting point. With this configuration, by performing appropriate heating, the liquefied low-melting-point portion 21a can be encased in the softened high-melting-point portion 21b of the outermost layer. This allows the liquefied low-melting-point portion 21a to be pulled out of the optical fiber groove 9 while encased in the high-melting-point portion 21b, reducing the effort required to scrape out the liquefied material from the optical fiber groove 9.

As mentioned above, it is preferable that the optical fiber groove 9 has the smallest possible cross-section. Therefore, the optical fiber groove 9 is formed with the smallest possible cross-section while still being able to accommodate the optical fiber cable 11 and sufficiently filling it with the curable material without any voids. The size of the groove-forming member 21 is determined in accordance with the size of the optical fiber groove 9.

Furthermore, in this embodiment, the methods described in Figures 4(a) and 4(b) may be carried out in accordance with the first embodiment. Also, in this embodiment, the structure described in Figure 4(c) may be adopted in accordance with the first embodiment.

As described above, the optical fiber laying method of this embodiment is an optical fiber laying method for laying an optical fiber cable 11 near the surface 1a of a concrete structure 1, and comprises a structure construction step in which a groove forming member 21 is installed on the inner surface of a concrete formwork 3 and concrete is poured, thereby constructing a concrete structure 1 in which an optical fiber groove 9 is formed on the surface 1a as the removal site of the groove forming member 21; and an optical fiber installation step in which an optical fiber cable 11 is installed in the optical fiber groove 9, a hardening material is filled and hardened, and the concrete structure 1 and the optical fiber cable 11 are integrated via the hardening material. Furthermore, in the structure construction step, after constructing the concrete structure 1 with the groove forming member 21 made of a thermoplastic material embedded in the surface 1a, the groove forming member 21 is heated and altered and removed from the concrete structure 1, thereby forming the optical fiber groove 9 as the removal site.

Furthermore, the optical fiber laying method of this embodiment is an optical fiber laying method for laying an optical fiber cable 11 near the surface 1a of a concrete structure 1, and comprises a structure construction step of constructing a concrete structure 1 in which an optical fiber groove 9 is formed on the surface 1a, and an optical fiber installation step of installing the optical fiber cable 11 in the optical fiber groove 9 and integrating the concrete structure 1 and the optical fiber cable 11. In the structure construction step, a groove forming member 21 is installed on the inner surface of the concrete formwork 3 and concrete is poured, so that the optical fiber groove 9 is formed on the surface 1a of the concrete structure 1 as the trace left by the removal of the groove forming member 21.

In this embodiment of the optical fiber laying method, the same effects and advantages as those of the optical fiber laying method of the first embodiment can be obtained.

[Third Embodiment]
Next, a method for laying optical fibers according to the third embodiment will be described. This laying method comprises a structure construction step and an optical fiber installation step, which will be described below.

(frame construction process)
In the structural construction process of this embodiment, as shown in Figures 7(a) and 7(b), instead of the chamfer strip 5 in the first embodiment, the optical fiber encapsulating member 23 is attached to the inner surface of the formwork 3 along the planned laying position of the optical fiber cable 11. Subsequently, reinforcement, formwork installation, concrete pouring and curing, and formwork removal are carried out in the same manner as in the structural construction process of the first embodiment, and the concrete structure 1 is completed. As shown in Figure 8(a), the optical fiber encapsulating member 23 is left embedded in the surface 1a of the concrete structure 1.

Here, the optical fiber encapsulating member 23 will be described. The optical fiber encapsulating member 23 has two surface layers 23s located along the surface 1a of the concrete structure 1, and an encapsulating portion 23t located between the two surface layers 23s and embedded inside the concrete structure 1, enclosing the optical fiber cable 11.

The cross-sectional shape of the enclosing portion 23t is such that it does not easily come out from the surface 1a of the concrete structure 1. For example, in the examples of Figures 7 and 8(a), the cross-sectional shape of the enclosing portion 23t is a trapezoidal shape that widens as it goes deeper from the surface 1a of the concrete structure 1. Furthermore, the enclosing portion 23t is hollow in order to enclose the optical fiber cable 11 in the hollow part. Specifically, the enclosing portion 23t has an optical fiber groove 9 formed as the hollow part, which opens on the surface 1a side of the concrete structure 1 and is recessed inward from the surface 1a of the concrete structure 1. The outline of this optical fiber groove 9 is located along the outline of the outer circumference of the enclosing portion 23t. That is, the optical fiber groove 9, like the enclosing portion 23t, has a trapezoidal shape that widens as it goes deeper from the surface 1a of the concrete structure 1. The shape of the enclosing portion 23t described above prevents the optical fiber enclosing member 23 from peeling off from the concrete structure 1. Furthermore, as will be described later, it also prevents the embedded layer 13 formed in the optical fiber groove 9 from peeling off from the optical fiber enclosing member 23.

The surface layer 23s extends along the surface 1a of the concrete structure 1, spreading outwards from the optical fiber groove 9 on both sides. The surface of the surface layer 23s facing the formwork 3 is the adhesive surface 23a. Before concrete pouring, this adhesive surface 23a is bonded to the inner surface of the formwork 3, thereby attaching the optical fiber encapsulating member 23 to the inner surface of the formwork 3 as described above. The adhesion of the adhesive surface 23a to the inner surface of the formwork 3 prevents the poured concrete from entering the optical fiber groove 9. On the other hand, during demolding, the optical fiber encapsulating member 23 needs to be detached from the inner surface of the formwork 3 and left on the concrete structure 1 side. Therefore, it is preferable to use double-sided tape or similar adhesive with sufficient adhesive strength to be easily removed by hand for bonding the adhesive surface 23a to the inner surface of the formwork 3.

Furthermore, since the optical fiber encapsulating member 23 is left in the concrete structure 1, it is preferable that the material of the optical fiber encapsulating member 23 be a non-ferrous material. For example, FRP material may be used as the material for the optical fiber encapsulating member 23. The optical fiber encapsulating member 23 is formed with the smallest possible cross-section without impairing the workability of the optical fiber installation process described below. In addition, to improve the integration between the optical fiber encapsulating member 23 and the concrete structure 1, irregularities may be formed on the surface of the optical fiber encapsulating member 23 (the surface in contact with the concrete).

(Optical fiber installation process)
The optical fiber installation process in this embodiment is performed in the same manner as in the optical fiber installation process in the first embodiment. That is, the optical fiber cable 11 is installed in the optical fiber groove 9, which is the hollow part of the optical fiber encapsulating member 23, and then a curable material is filled into the optical fiber groove 9, and the curable material hardens with the optical fiber cable 11 embedded in it. As a result, as shown in Figure 8(b), the concrete structure 1 and the optical fiber cable 11 are integrated via the embedded layer 13 and the optical fiber encapsulating member 23, which are made of the hardened curable material. The optical fiber cable 11 is encapsulated in the optical fiber encapsulating member 23 and laid embedded at a position slightly deep from the surface 1a of the concrete structure 1.

The shape of the optical fiber encapsulating member 23 is not limited to those shown in Figures 7 and 8(a). Other shapes are acceptable as long as they prevent the optical fiber encapsulating member 23 from easily detaching from the surface 1a of the concrete structure 1. For example, as shown in Figure 8(c), the encapsulating portion 23t may have a circular cross-section. Alternatively, the shape of the optical fiber encapsulating member 23 may be as shown in Figure 8(d). The optical fiber encapsulating member 23 in Figure 8(d) has a rectangular cross-section encapsulating portion 23t, and a T-shaped anchor portion 23b extending from the center of the encapsulating portion 23t to a deeper position in the concrete structure 1. The presence of this anchor portion 23b makes it difficult for the optical fiber encapsulating member 23 to detach from the surface 1a of the concrete structure 1.

Furthermore, in this embodiment, the methods described in Figures 4(a) and 4(b) may be carried out in accordance with the first embodiment. Also, in this embodiment, the structure described in Figure 4(c) may be adopted in accordance with the first embodiment.

As described above, the optical fiber laying method of this embodiment is an optical fiber laying method for laying an optical fiber cable 11 near the surface 1a of a concrete structure 1, and comprises a structure construction step in which an optical fiber encapsulating member 23 is installed on the inner surface of a concrete formwork 3 and concrete is poured to construct a concrete structure 1 in which the optical fiber encapsulating member 23 is embedded in the surface 1a, and an optical fiber installation step in which the optical fiber cable 11 is inserted into the optical fiber encapsulating member 23 on the surface 1a of the concrete structure 1, and the concrete structure 1 and the optical fiber cable 11 are integrated via the optical fiber encapsulating member 23. Furthermore, in the optical fiber installation step, the optical fiber cable 11 is installed in an optical fiber groove 9 provided in the optical fiber encapsulating member 23 and opening on the surface 1a side of the concrete structure 1, and a hardening material is filled and hardened, thereby integrating the concrete structure 1 and the optical fiber cable 11 via the hardening material and the optical fiber encapsulating member 23.

Furthermore, the optical fiber laying method of this embodiment is an optical fiber laying method for laying an optical fiber cable 11 near the surface 1a of a concrete structure 1, and comprises a structure construction step of constructing a concrete structure 1 in which an optical fiber groove 9 is formed on the surface 1a, and an optical fiber installation step of installing the optical fiber cable 11 in the optical fiber groove 9 and integrating the concrete structure 1 and the optical fiber cable 11. In the structure construction step, an optical fiber encapsulating member 23, which is provided with an optical fiber groove 9 that opens on the surface 1a side of the concrete structure 1, is installed on the inner surface of a concrete formwork 3, and concrete is poured to construct a concrete structure 1 in which the optical fiber encapsulating member 23 is embedded in the surface 1a.

In this embodiment of the optical fiber laying method, the same effects and advantages as those of the optical fiber laying method of the first embodiment can be obtained.

[Fourth Embodiment]
Next, a method for laying optical fibers according to the fourth embodiment will be described. This laying method comprises a structure construction step and an optical fiber installation step, which will be described below.

(frame construction process)
In the structural construction process of this embodiment, as shown in Figures 9(a) and 9(b), instead of the chamfer strip 5 in the first embodiment, an optical fiber encapsulating member 27 made of thermoplastic resin is attached to the inner surface of the formwork 3 along the planned laying position of the optical fiber cable 11. Subsequently, reinforcement, formwork installation, concrete pouring and curing, and demolding are carried out in the same manner as in the structural construction process of the first embodiment, and the concrete structure 1 is completed. As shown in Figure 10(a), the optical fiber encapsulating member 23 is left embedded in the surface 1a of the concrete structure 1.

Here, the optical fiber encapsulating member 27 will be described. The optical fiber encapsulating member 27 has substantially the same configuration as the groove forming member 21 in the second embodiment, and in addition to the groove forming member 21, it has a notched groove 29. Similar to the groove forming member 21, the optical fiber encapsulating member 27 has a cross-sectional shape that prevents it from easily coming out of the surface 1a of the concrete structure 1, thereby suppressing the peeling of the optical fiber encapsulating member 27 from the concrete structure 1. The notched groove 29 is provided so as to be cut from the surface 1a side toward the interior side, with the groove depth direction being perpendicular to the surface 1a of the concrete structure 1, and is a groove that extends along the entire length of the optical fiber encapsulating member 27. The groove width of the notched groove 29 may be substantially the same as the diameter of the optical fiber cable 11 (for example, 0.9 mm), or it may be slightly smaller than the diameter of the optical fiber cable 11. Furthermore, the notched groove 29 reaches a position deeper than the center of the optical fiber encapsulating member 27. Examples of thermoplastic resins used for the optical fiber encapsulating member 27 include polyurethane resins with a low melting point (melting point of approximately 60-80°C).

(Optical fiber installation process)
In the optical fiber installation process of this embodiment, the notched groove 29 of the optical fiber encapsulating member 27 is pushed open in the groove width direction, and the optical fiber cable 11 is pushed into the notched groove 29 from the surface 1a side. For example, the optical fiber encapsulating member 27 may be slightly heated to facilitate the expansion of the notched groove 29. Then, as shown in Figure 10(b), the optical fiber cable 11 is pushed in, for example, to the bottom surface of the notched groove 29, and is inserted into a position deeper than the center of the optical fiber encapsulating member 27.

From this state, the optical fiber encapsulating member 27 is heated. As the optical fiber encapsulating member 27, which is made of thermoplastic resin, is heated, the groove sides of the notched groove 29 fuse together, and the notched groove 29 is closed. After that, when the heating is stopped and the optical fiber encapsulating member 27 is cooled by natural heat dissipation and hardens again, the optical fiber cable 11 becomes enclosed within the optical fiber encapsulating member 27, as shown in Figure 10(c). As a result, the concrete structure 1 and the optical fiber cable 11 are integrated via the optical fiber encapsulating member 27. The optical fiber cable 11 is encapsulated in the optical fiber encapsulating member 27 and laid embedded at a position slightly deeper than the surface 1a of the concrete structure 1. As for the heating method of the optical fiber encapsulating member 27, a method similar to the heating method example of the groove forming member 21 (Figure 6(a)) in the second embodiment described above can be used. Furthermore, the heating temperature of the optical fiber encapsulating member 27 should be appropriately set according to the material properties of the optical fiber encapsulating member 27 to suit the purpose of the optical fiber installation process in this embodiment.

As described above, the optical fiber laying method of this embodiment is an optical fiber laying method for laying an optical fiber cable 11 near the surface 1a of a concrete structure 1, and comprises a structure construction step in which an optical fiber encapsulating member 27 is installed on the inner surface of a concrete formwork 3 and concrete is poured to construct a concrete structure 1 in which the optical fiber encapsulating member 27 is embedded in the surface 1a, and an optical fiber installation step in which the optical fiber cable 11 is inserted into the optical fiber encapsulating member 27 on the surface 1a of the concrete structure 1, thereby integrating the concrete structure 1 and the optical fiber cable 11 via the optical fiber encapsulating member 27. Furthermore, in the optical fiber installation step, after inserting the optical fiber cable 11 into a notch 29 cut into the optical fiber encapsulating member 27 made of thermoplastic resin and cut from the surface 1a side of the concrete structure 1, the optical fiber encapsulating member 27 is heated to fuse and close the notch 29, thereby integrating the concrete structure 1 and the optical fiber cable 11 via the optical fiber encapsulating member 27.

Furthermore, the optical fiber laying method of this embodiment is an optical fiber laying method for laying an optical fiber cable 11 near the surface 1a of a concrete structure 1, and comprises a structure construction step of constructing a concrete structure 1 in which an optical fiber groove (cut groove 29) is formed on the surface 1a, and an optical fiber installation step of installing the optical fiber cable 11 in the cut groove 29 and integrating the concrete structure 1 and the optical fiber cable 11. In the structure construction step, an optical fiber encapsulating member 27, which is provided with a cut groove 29 that opens on the surface 1a side of the concrete structure 1, is installed on the inner surface of a concrete formwork 3, and concrete is poured to construct a concrete structure 1 in which the optical fiber encapsulating member 27 is embedded in the surface 1a.

In this embodiment of the optical fiber laying method, the same effects and advantages as those of the first embodiment can be obtained. Furthermore, compared to the first embodiment, this embodiment eliminates the need to form an embedded layer 13 for embedding the optical fiber cable 11, and eliminates the need to fill the optical fiber groove 9 with a curable material.

In this embodiment of the optical fiber laying method, the notched groove 29 in the optical fiber encapsulating member 27 can be omitted. In this case, during the optical fiber installation process, once the optical fiber encapsulating member 27 has been heated and softened, the optical fiber cable 11 can be embedded by pushing it into the interior of the optical fiber encapsulating member 27 while deforming the optical fiber encapsulating member 27. Furthermore, as shown in Figures 10(d) and 10(e), the optical fiber encapsulating member 27 may be such that the notched groove 29 is formed in the groove-forming member 21 shown in Figure 6(d) or Figure 6(e). The notched groove 29 may also be formed immediately before the optical fiber installation process by a worker cutting the optical fiber encapsulating member 27 from the concrete structure 1 side using a cutter or the like.

Furthermore, in this embodiment, the methods described in Figures 4(a) and 4(b) may be carried out in accordance with the first embodiment. Also, in this embodiment, the structure described in Figure 4(c) may be adopted in accordance with the first embodiment.

[Fifth Embodiment]
Next, a method for laying optical fibers according to the fifth embodiment will be described. This laying method comprises a structure construction step and an optical fiber installation step, which will be described below.

(frame construction process)
In the structural construction process of this embodiment, as shown in Figures 11(a) and 11(b), instead of the chamfer strip 5 in the first embodiment, the optical fiber encapsulating member 31 is attached to the inner surface of the formwork 3 along the planned laying position of the optical fiber cable 11. Subsequently, reinforcement, formwork installation, concrete pouring and curing, and formwork removal are carried out in the same manner as in the structural construction process of the first embodiment, and the concrete structure 1 is completed. As shown in Figure 12(a), the optical fiber encapsulating member 31 is left embedded in the surface 1a of the concrete structure 1.

Here, the optical fiber encapsulating member 31 will be described. The optical fiber encapsulating member 31 has a tubular body 33 made of thermoplastic resin with a circular cross-section, and granular material 35 made of thermoplastic resin filled in the hollow portion of the tubular body 33. The shape of the optical fiber encapsulating member 31 is not limited to a circular cross-section as long as it is a shape that does not easily come off the surface 1a of the concrete structure 1. For example, it may have a cross-sectional shape as shown in Figure 6(a), Figure 6(d), or Figure 6(e), following the groove forming member 21. This prevents the optical fiber encapsulating member 31 from peeling off from the concrete structure 1. An example of the thermoplastic resin mentioned above is polyurethane resin, which has a low melting point (melting point of about 60 to 80°C). The material of the tubular body 33 and the material of the granular material 35 may be different. Also, as will be described later, it is necessary to cut the tubular body 33 to form an opening 33a, so the tubular body 33 is made of a material that can be cut with a cutter or the like. The optical fiber encapsulating member 31 is formed with the smallest possible cross-section without impairing the workability of the optical fiber installation process described below. Furthermore, to improve the integration between the optical fiber encapsulating member 31 and the concrete structure 1, irregularities may be formed on the surface of the tubular body 33 (the surface in contact with the concrete).

(Optical fiber installation process)
In the optical fiber installation process of this embodiment, as shown in Figure 12(b), the tubular wall of the tubular body 33 of the optical fiber encapsulating member 31, which is exposed on the surface 1a of the concrete structure 1, is cut open with a cutter or the like, and the optical fiber cable 11 is inserted into the hollow part of the tubular body 33. That is, the optical fiber cable 11 is pushed into the gaps between the granular bodies 35 while pushing them aside from the outside through the cut opening 33a (optical fiber insertion opening) of the cut tubular body 33. The optical fiber cable 11 is then embedded between the granular bodies 35 at approximately the center of the optical fiber encapsulating member 31.

From this state, the optical fiber encapsulating member 31 is heated. As the tubular body 33 and granular body 35 made of thermoplastic resin are heated, the particles of the tubular body 33 and granular body 35 fuse together, and the optical fiber cable 11 is integrated while being enclosed. After that, heating is stopped and the optical fiber encapsulating member 31 is cooled by natural heat dissipation and hardens again, resulting in a state in which the optical fiber cable 11 is enclosed within the integrated optical fiber encapsulating member 31, as shown in Figure 12(c). As a result, the concrete structure 1 and the optical fiber cable 11 are integrated via the optical fiber encapsulating member 31. The optical fiber cable 11 is enclosed in the optical fiber encapsulating member 31 and laid embedded at a position slightly deeper than the surface 1a of the concrete structure 1. As a method for heating the optical fiber encapsulating member 31, a method similar to the heating method example of the groove forming member 21 (Figure 6(a)) in the second embodiment described above can be used. Furthermore, the heating temperature of the optical fiber encapsulating member 31 should be appropriately set according to the material properties of the optical fiber encapsulating member 31 to suit the purpose of the optical fiber installation process in this embodiment.

Furthermore, in this embodiment, the methods described in Figures 4(a) and 4(b) may be carried out in accordance with the first embodiment. Also, in this embodiment, the structure described in Figure 4(c) may be adopted in accordance with the first embodiment.

As described above, the optical fiber laying method of this embodiment is an optical fiber laying method for laying an optical fiber cable 11 near the surface 1a of a concrete structure 1, and comprises a structure construction step of constructing a concrete structure 1 in which an optical fiber encapsulating member 31 is installed on the inner surface of a concrete formwork 3 and concrete is poured, thereby constructing a concrete structure 1 in which the optical fiber encapsulating member 31 is embedded in the surface 1a, and an optical fiber installation step of inserting an optical fiber cable 11 into the optical fiber encapsulating member 31 on the surface 1a of the concrete structure 1, thereby integrating the concrete structure 1 and the optical fiber cable 11 via the optical fiber encapsulating member 31. Furthermore, the optical fiber encapsulating member 31 comprises a tubular body 33 and granular material 35 made of thermoplastic resin filled inside the tubular body 33. In the optical fiber installation process, the optical fiber cable 11 is inserted into the gaps between the granular material 35 through an optical fiber insertion port (cutout 33a) provided in the tubular body 33 and opening on the surface 1a side of the concrete structure 1. The optical fiber encapsulating member 31 is then heated to fuse the granular material 35 together, thereby integrating the concrete structure 1 and the optical fiber cable 11 via the optical fiber encapsulating member 31.

In this embodiment of the optical fiber laying method, the same effects and advantages as those of the first embodiment can be obtained. Furthermore, compared to the first embodiment, this embodiment eliminates the need to form an embedded layer 13 for embedding the optical fiber cable 11, and eliminates the need to fill the optical fiber groove 9 with a curable material.

The present invention can be implemented in various forms, including the embodiments described above, by making various modifications and improvements based on the knowledge of those skilled in the art. Furthermore, it is possible to construct modified versions by utilizing the technical matters described in the embodiments described above. The configurations of each embodiment may be used in appropriate combinations.

1…Concrete structure, 1a…Surface, 3…Concrete formwork, 5…Cover strip (groove forming member), 9…Fiber optic groove, 11…Fiber optic cable, 13…Embedding layer, 21…Groove forming member, 23, 27, 31…Fiber optic encasing members, 29…Cut groove, 31…Fiber optic encasing member, 33…Tubular body, 35…Granular body, 33a…Cut opening (fiber optic insertion port).

Claims (6)

A method for laying optical fibers near the surface of a structural frame for detecting strain or temperature of the structural frame ,
A frame construction step is to construct the frame in which a groove-forming member is installed on the inner surface of the concrete formwork, concrete is poured into the formwork, and a groove for optical fibers is formed on the surface as a trace of the removal of the groove-forming member,
A fiber optic installation step involves placing the optical fiber in the groove for the optical fiber, filling it with a curable material and curing it, and integrating the frame and the optical fiber via the curable material.
A method for laying optical fibers, comprising the following features.
In the aforementioned structural construction process,
The optical fiber laying method according to claim 1, wherein the groove forming member is installed as a chamfer on the inner surface of the concrete formwork and concrete is poured. A method for laying optical fibers near the surface of a building structure,
A frame construction step involves installing a groove-forming member on the inner surface of a concrete formwork and pouring concrete, thereby constructing the frame in which a groove for optical fibers is formed on the surface as a trace of the removal of the groove-forming member,
A fiber optic installation step involves placing the optical fiber in the groove for the optical fiber, filling it with a curable material and curing it, and integrating the frame and the optical fiber via the curable material.
Equipped with ,
In the aforementioned structural construction process,
A method for laying optical fibers, comprising constructing the frame with the groove-forming member made of a thermoplastic material embedded in the surface, then heating and altering the groove-forming member and removing it from the frame, thereby forming the optical fiber groove as the removal mark. A method for laying optical fibers near the surface of a building structure,
A structural construction step involves installing an optical fiber encapsulating member on the inner surface of a concrete formwork and pouring concrete to construct the structural body in which the optical fiber encapsulating member is embedded on the surface,
An optical fiber installation step involves inserting the optical fiber into the optical fiber enclosing member on the surface of the frame, thereby integrating the frame and the optical fiber via the optical fiber enclosing member.
Equipped with,
In the optical fiber installation process,
A method for laying optical fibers, comprising: placing the optical fiber in an optical fiber groove provided in the optical fiber encapsulating member and opening on the surface side of the frame; filling the groove with a curable material and curing it; and integrating the frame and the optical fiber via the curable material and the optical fiber encapsulating member. A method for laying optical fibers near the surface of a building structure,
A structural construction step involves installing an optical fiber encapsulating member on the inner surface of a concrete formwork and pouring concrete to construct the structural body in which the optical fiber encapsulating member is embedded on the surface,
An optical fiber installation step involves inserting the optical fiber into the optical fiber encapsulating member on the surface of the frame, thereby integrating the frame and the optical fiber via the optical fiber encapsulating member.
Equipped with,
In the optical fiber installation process,
A method for laying optical fibers, comprising: inserting the optical fiber into a notched groove cut from the surface side of the frame, provided in the optical fiber encapsulating member made of thermoplastic resin; heating the optical fiber encapsulating member to fuse and close the notched groove; and integrating the frame and the optical fiber via the optical fiber encapsulating member. A method for laying optical fibers near the surface of a building structure,
A structural construction step involves installing an optical fiber encapsulating member on the inner surface of a concrete formwork and pouring concrete to construct the structural body in which the optical fiber encapsulating member is embedded on the surface,
An optical fiber installation step involves inserting the optical fiber into the optical fiber encapsulating member on the surface of the frame, thereby integrating the frame and the optical fiber via the optical fiber encapsulating member.
Equipped with,
The optical fiber encapsulating member comprises a tubular body and granular material made of thermoplastic resin filled inside the tubular body.
In the optical fiber installation process,
A method for laying optical fibers, comprising: inserting the optical fiber into the gaps between the granular particles through an optical fiber insertion port provided in the tubular body and opening on the surface side of the frame; heating the optical fiber enclosing member to fuse the granular particles together and integrate them; and integrating the frame and the optical fiber via the optical fiber enclosing member.