JP7080554B2 - Fixed disc for tunnel tarpaulin - Google Patents

Description

The present invention relates to a fixed disk for fixing the waterproof sheet to the peripheral wall of a tunnel, and particularly to a fixed disk for fixing the waterproof sheet by utilizing electromagnetic induction heating.

For example, in the NATM (New Austrian tunneling Method) method and the SENS (Shield / ECL / NATM / System) method, a waterproof sheet is provided on the peripheral wall of the tunnel. Generally, the waterproof sheet has a laminated structure of a water-permeable back cushioning material on the primary lining side and an impermeable waterproof sheet material on the secondary lining side (see, for example, Patent Document 1 and the like). One waterproof sheet usually has a width of about 2 m. The waterproof sheet is stretched in the circumferential direction of the primary lining with the width direction facing the tunnel axial direction. A plurality of waterproof sheets are arranged and joined in the direction of the tunnel axis at intervals of about 2 m.

Joining the tarpaulins every 2 m at the tunnel construction site may lead to a long construction period and poor joining. Therefore, for example, three waterproof sheets may be lined up in a factory to have a width of about 6 m before being carried to the tunnel construction site. By doing so, the amount of work for joining the waterproof sheet at the tunnel construction site can be reduced to one-third, and the possibility of poor joining can be reduced to one-third.

Japanese Unexamined Patent Publication No. 2004-060217

A wide waterproof sheet having a width of about 6 m or the like is fixed to the primary lining using, for example, a fixing disk. The fixed disk is provided with a hot melt layer on the surface of an induction heater made of metal. After fixing the fixing disc directly to the primary lining with a fixing member such as a concrete nail or an anchor or via a back cushioning material, a waterproof sheet material is stretched over the fixing disc. Then, the induction heating body is electromagnetically induced and heated by an electromagnetic induction heating device from the surface side (inside the tunnel) of the waterproof sheet. As a result, the hot melt layer is melted and adhered to the waterproof sheet.
However, if the fixed disk is overheated by electromagnetic induction, the waterproof sheet may be melted. Leakage may occur depending on the degree of melting.
In view of such circumstances, it is an object of the present invention to provide a fixed disk for a tunnel waterproof sheet capable of preventing the waterproof sheet from being melted by excessive electromagnetic induction heating.

The inventor has stated that a fixed disk using a metal film of a certain shape as an induction heater will crack at a specific location and break if it is over-heated by electromagnetic induction, and will not be heated even if an induced magnetic field is applied thereafter. discovered.
The present invention has been made based on such findings, and is a fixed disk for a tunnel waterproof sheet for fixing the waterproof sheet to the peripheral wall of the tunnel.
A base provided with a fixing penetration part through which the fixing member is penetrated,
An annular metal film provided on the surface of the base so as to surround the fixing penetration portion and electromagnetically induced and heated.
A hot melt layer laminated on the surface of the annular metal film, and the like.
It is characterized in that a local easily broken portion due to the electromagnetic induction heating is provided at a predetermined position in the circumferential direction of the annular metal film.

The fixing disk is fixed to the tunnel peripheral wall such as a primary lining by a fixing member such as a concrete nail or an anchor bolt. Further, the hot melt layer is melted and adhered to the waterproof sheet by appropriate electromagnetic induction heating of the annular metal film. As a result, the tarpaulin is fixed to the peripheral wall of the tunnel via the fixing disk.
When excessive electromagnetic induction heating is performed, cracks are formed between the inner peripheral edge and the outer peripheral edge of the easily broken portion and the broken portion is likely to be broken. Once the annular metal film is broken, it cools without being heated even when an induced magnetic field is applied. Therefore, the annular metal film acts like a fuse to prevent excessive electromagnetic induction heating. As a result, the waterproof sheet can be prevented from melting, and water leakage from the molten portion can be prevented.

It is preferable that the distance connecting the inner peripheral edge and the outer peripheral edge at various points in the circumferential direction of the annular metal film is locally small at the easily broken portion.
As a result, when the amount of electromagnetic induction heating is exceeded, it becomes easy to break at the easily broken portion.

It is preferable that the outer peripheral edge of the annular metal film is quadrangular and the inner peripheral edge of the annular metal film is circular.
As a result, an easily broken portion is formed between the middle portion of at least one side of the outer peripheral edge of the quadrangle and the inner peripheral edge of the circle in the annular metal film, and cracks are likely to occur there when the amount of electromagnetic induction heating is exceeded.

The thickness of the annular metal film is preferably 10 μm to 100 μm.
As a result, the annular metal film is appropriately electromagnetically induced and heated so that the hot melt layer can be reliably melted and the waterproof sheet can be joined, and the easily broken portion is surely broken when the electromagnetic induction heating is excessively performed. Can be done. If it is less than 10 μm, the easily broken portion may be broken before the electromagnetic induction heating is sufficiently performed, and the waterproof sheet may not be adhered. If it exceeds 100 μm, the waterproof sheet may melt before the easily broken portion is broken.

According to the present invention, it is possible to prevent the waterproof sheet from being melted by excessive electromagnetic induction heating of the fixed disk for the tunnel waterproof sheet.

FIG. 1 is a front view showing a fixed disk for a tunnel tarpaulin according to the first embodiment of the present invention in a state before use. FIG. 2 is a cross-sectional view taken along the line II-II of FIG. FIG. 3A is a perspective view of the tunnel waterproof sheet fixing disk as viewed from the front side. FIG. 3B is a perspective view of the tunnel waterproof sheet fixing disk as viewed from the back surface side. FIG. 4 is an enlarged cross-sectional view of the circle portion IV of FIG. FIG. 5 is a cross-sectional view showing a tunnel including a waterproof sheet fixed by using the tunnel waterproof sheet fixing disk in a cross section orthogonal to the tunnel axis. FIG. 6 is a cross-sectional view taken along the VI-VI line of FIG. 5 showing the tunnel in a state after the waterproof sheet is stretched and before the secondary lining (two-dot chain line in the figure) is placed. FIG. 7 is an enlarged cross-sectional view showing the circular portion VII of FIG. 6 in a step of fixing the waterproof sheet material by electromagnetic induction heating. FIG. 8 is a front view showing the tunnel waterproof sheet fixing disk in a state of being overheated by electromagnetic induction. FIG. 9 is a front view of the fixed disk for the tunnel tarpaulin according to the second embodiment of the present invention. FIG. 10 is a photograph showing the results of Example 1.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
<First Embodiment>
1 to 8 show the first embodiment of the present invention. As shown in FIG. 5, for example, the ground 2 is excavated by the NATM method to form the tunnel 1. The peripheral wall of the tunnel 1 has a layered structure in which the primary lining 3, the waterproof layer 4, and the secondary lining 5 are stacked in this order from the inner wall 2a side of the excavated ground 2 to the inside of the tunnel.

As shown in FIGS. 5 and 6, the waterproof layer 4 includes a plurality of waterproof sheets 10. Each waterproof sheet 10 includes a waterproof sheet material 11 and a back surface cushioning material 12. The waterproof sheet material 11 faces the secondary lining 5, and the back cushioning material 12 faces the primary lining 3.
In FIG. 5, the thicknesses of the waterproof sheet material 11 and the back surface cushioning material 12 are exaggerated with respect to the thicknesses of the primary lining 3 and the secondary lining 5.

The waterproof sheet material 11 has water impermeability and has a waterproof function of preventing spring water from the ground 2 from flowing into the tunnel 1. Examples of the material of the waterproof sheet material 11 include thermoplastic resins such as ethylene-vinyl acetate copolymer resin (EVA), polyolefin, and polyvinyl chloride (PVC), and EVA is preferable.

The back surface cushioning material 12 is laminated on the back surface of the waterproof sheet material 11 (the surface to face the primary lining 3 side, the upper surface in FIG. 6). The back surface cushioning material 12 is made of a non-woven fabric or the like. Examples of the material of the non-woven fabric include chemical fibers such as polyester, polypropylene (PP) and polyethylene (PE), natural fibers such as coconut husk, cotton, linen, wool and silk, and inorganic fibers such as glass, carbon, metal and ceramic. However, it is preferably a chemical fiber. The back surface cushioning material 12 has a cushioning function between the primary lining 3 or the ground 2 and the secondary lining 5, as well as a drainage function for discharging spring water from the ground 2.

The width of one waterproof sheet 10 (dimensions in the left-right direction in FIG. 6) is about 2 m. The waterproof sheet 10 is stretched along the inner surface of the primary lining 3 with the width direction facing the tunnel axial direction and the longitudinal direction facing the tunnel circumferential direction. Further, a plurality of waterproof sheets 10 are connected in the direction of the tunnel axis to construct a waterproof layer 4.

As shown in FIG. 6, the waterproof sheet 10 is fixed to the primary lining 3 (peripheral wall) by the fixing means 6. The fixing means 6 includes a fixing disc 20 for a tunnel waterproof sheet and concrete nails 31 and 32. The joint portion between the ends of the two adjacent back surface cushioning materials 12 is fixed to the primary lining 3 by the concrete nail 31.

As shown in FIG. 7, the fixed disk 20 is arranged between the back cushioning material 12 and the waterproof sheet material 11. The fixing disk 20 and the back surface cushioning material 12 are fixed to the primary lining 3 by the concrete nail 32 (fixing member). Further, the fixed disk 20 is joined to the waterproof sheet material 11 by electromagnetic induction heating welding.

As shown in FIG. 1, the fixed disk 20 includes a base 21 and an induction heating adhesive sheet 22. The base 21 has a square-shaped (square-shaped) plate shape. As shown in FIGS. 2 and 3A, the front side surface (the surface facing the secondary lining 5 and the upper surface in FIG. 2) of the base 21 is a flat surface. As shown in FIG. 3B, reinforcing ribs 21b are radially formed on the back surface of the base 21 (the surface facing the primary lining 3). The material of the base 21 is, for example, EVA, PP, PE, PVC or other resin, preferably EVA.

As shown in FIGS. 1 to 3, a fixing penetration portion 23 is provided in the central portion of the base 21. The fixing penetration portion 23 includes a tubular portion 23a and a bottom plate portion 23b. The tubular portion 23a is formed in a cylindrical shape and protrudes from the front side surface of the base 21 to the back side (lower side in FIG. 2). The internal space of the tubular portion 23a is opened on the front side surface of the base 21. Three (plural) locking claws 23f are formed on the inner peripheral surface of the tubular portion 23a at intervals in the circumferential direction. The back end (lower end in FIG. 2) of the tubular portion 23a is closed by the bottom plate portion 23b. The bottom plate portion 23b is positioned so as to project to the back side (lower side in FIG. 2) from the base 21.

As shown in FIG. 2, a circular fixing plate 24 is housed inside the fixing penetration portion 23. The fixing plate 24 is made of, for example, a hot-dip galvanized steel plate. The fixing plate 24 is overlapped with the inner bottom surface of the bottom plate portion 23b and is locked to the locking claw 23f to prevent it from coming off.
As shown in FIG. 7, in the tunnel 1, the concrete nail 32 (fixing member) penetrates the bottom of the fixing plate 24 and the fixing penetration portion 23 and is driven into the primary lining 3.

As shown in FIG. 2, an induction heating adhesive sheet 22 is provided on the front surface surface (the surface facing the secondary lining 5) of the base 21. As shown in FIG. 4, the induction heating adhesive sheet 22 has a three-layer laminated structure of an adhesive film layer 25, an annular metal film 26 (induction heating body), and a hot melt layer 27. The adhesive film layer 25 is laminated on the back surface (lower surface in FIG. 4) of the annular metal film 26, and the hot melt layer 27 is laminated on the front surface (upper surface in FIG. 4) of the annular metal film 26. The adhesive film layer 25 is adhered to the base 21.
In the tunnel 1, the hot melt layer 27 is melted and joined to the waterproof sheet material 11 (see FIG. 7).

The material of the annular metal film 26 is made of a metal such as aluminum (Al). The thickness of the annular metal film 26 is preferably about 10 μm to 100 μm.

As shown in FIG. 1, a circular center hole 26c is formed in the central portion of the annular metal film 26. The fixing penetration portion 23 is arranged inside the center hole 26c. In short, the shape of the annular metal film 26 and thus the induction heating adhesive sheet 22 is an annular shape surrounding the fixing penetration portion 23. The outer peripheral edge of the annular metal film 26 is a quadrangle along the outer peripheral edge of the base 21. The inner peripheral edge of the annular metal film 26 is circular.

Due to the difference in shape between the outer peripheral edge and the inner peripheral edge, the distance D ₂₆ between the peripheral edges connecting the outer peripheral edge and the inner peripheral edge differs depending on the position in the circumferential direction of the annular metal film 26. Here, the inter-peripheral distance D ₂₆ refers to the shortest distance from an arbitrary point on the outer peripheral edge of the annular metal film 26 to the inner peripheral edge (edge of the central hole 26c). The maximum value D _26max of the inter-peripheral distance D ₂₆ is from the four R-shaped corners of the outer peripheral edge of the annular metal film 26 to the central hole 26c. The minimum value D 26 min of the inter-peripheral distance D ₂₆ is from the middle portion of the four sides of the outer peripheral edge of the annular metal film 26 to the center hole _26c . The path portion of the annular metal film 26 having a minimum value D ₂₆ min between peripheral _edges is easily broken locally by electromagnetic induction heating, and constitutes an easily broken portion 28.
In other words, a local easily broken portion 28 by electromagnetic induction heating is provided at a predetermined position in the circumferential direction of the annular metal film 26. The distance D ₂₆ between the peripheral edges connecting the inner peripheral edge and the outer peripheral edge at various points in the circumferential direction of the annular metal film 26 is locally reduced at the easily broken portion 28.

The method of constructing the tunnel 1 will be described focusing on the method of using the fixed disk 20 for the tunnel waterproof sheet.
Preferably, in a factory, three sheets (several sheets) of each of the waterproof sheet material 11 having a width of about 2 m and the back cushioning material 12 are joined by welding or the like to form a wide sheet having a width of about 6 m. The waterproof sheet material 11 and the back surface cushioning material 12 are separately carried into the tunnel construction site without being joined at the factory.

At the tunnel construction site, when the excavation of the ground 2 and the construction of the primary lining 3 proceed by a predetermined span, the back cushioning material 12 integrated with three sheets is stretched over the inner peripheral surface (lower surface in FIG. 6) of the primary lining 3. .. The back surface cushioning material 12 is fixed to the primary lining 3 by the fixing means 6. The concrete nail 31 of the fixing means 6 is driven into the joint portion between the two adjacent back surface cushioning materials 12. Moreover, the fixing discs 20 are arranged at a plurality of places on the back surface cushioning material 12 and fastened with concrete nails 32 (FIG. 7).
Since the fixing penetration portion 23 of the fixed disk 20 protrudes from the base 21 toward the primary lining 3, even if the inner surface of the primary lining 3 is uneven, the fixed disk 20 is primarily covered with the back surface cushioning material 12. Can be stably fixed to the work 3.
Anchor bolts may be used instead of the concrete nails 31 and 32.

Another adjacent back surface cushioning material 12 is joined to the end of the three-sheet integrated back cushioning material 12 in the width direction by welding or the like. According to the back surface cushioning material 12 integrated with three sheets, the amount of joining work between the back surface cushioning materials 12 at the tunnel construction site can be reduced to one-third of the case where each sheet is performed, and the possibility of joint failure occurs 3. It can be reduced to one-third.

Next, the three waterproof sheet materials 11 are stretched so as to be overlapped on the inner surface side (lower side in FIG. 6) of the back surface cushioning material 12. The waterproof sheet material 11 covers the fixed disk 20.
Subsequently, as shown in FIG. 7, the probe 7b of the electromagnetic induction heater 7 is opposed to the fixed disk 20 with the waterproof sheet material 11 interposed therebetween, and the annular metal film 26 is electromagnetically induced heated. As a result, the hot melt layer 27 is melted and adhered to the waterproof sheet material 11. Preferably, the waterproof sheet material 11 can be firmly adhered by pressing the waterproof sheet material 11 against the fixed disk 20 with a probe 7b or the like. As a result, the waterproof sheet material 11 is joined to the back surface cushioning material 12 via the fixing disk 20 and is fixed to the primary lining 3.
The suitable electromagnetic induction heating time per fixed disk 20 depends on the thickness of the waterproof sheet material 11, the air temperature, and other on-site conditions, but is, for example, several seconds to ten and several seconds.

As shown in FIG. 8, when the fixed disk 20 is overheated by electromagnetic induction, a crack 28c is formed between the inner peripheral edge and the outer peripheral edge of the easily broken portion 28 in the annular metal film 26, and the annular metal film 26 is broken. .. Although the mechanism is not clear, in the easily broken portion 28, the energy density of electromagnetic induction becomes high because the distance D ₂₆ between the peripheral edges is locally small, and the temperature is higher than that of other parts of the annular metal film 26. Can be considered.
Once the annular metal film 26 is broken, it cools without being heated even when an induced magnetic field is applied. Therefore, the annular metal film 26 acts like a fuse, so that excessive electromagnetic induction heating can be prevented. As a result, the waterproof sheet 11 can be prevented from melting, and by extension, water leakage from the molten portion of the waterproof sheet 11 can be prevented.
By setting the thickness of the annular metal film 26 to 10 μm to 100 μm, it is possible to prevent the easily broken portion 28 from being broken before sufficient electromagnetic induction heating is completed. Therefore, the hot melt layer 27 can be reliably melted and adhered to the waterproof sheet material 11, and the waterproof sheet material 11 can be prevented from being melted before the easily broken portion 28 is broken.

Another adjacent waterproof sheet material 11 is joined to the end of the three-sheet waterproof sheet material 11 in the width direction by welding or the like. According to the three-sheet integrated waterproof sheet material 11, the amount of jointing work between the waterproof sheet materials 11 at the tunnel construction site can be reduced to one-third of the case where each sheet is performed, and the possibility of joint failure is reduced to 3. It can be reduced to one-third. As a result, the possibility of water leakage due to poor joining can be reduced to one-third.

After that, the secondary lining 5 is placed on the inner surface side (lower side in FIG. 6) of the waterproof sheet 10.
In this way, the tunnel 1 is constructed.

Next, another embodiment of the present invention will be described. In the following embodiments, the same reference numerals are given to the drawings for configurations that overlap with the above-described embodiments, and the description thereof will be omitted.
<Second Embodiment>
As shown in FIG. 9, in the tunnel waterproof sheet fixed disk 20B according to the second embodiment, the outer peripheral edge of the base 21 is circular. The annular metal film 40 has both an outer peripheral edge and an inner peripheral edge in a circular annular shape. Moreover, for example, a triangular notch 41 is formed at one position in the circumferential direction of the outer peripheral edge of the annular metal film 40. The distance D ₄₀ between the peripheral edges of the annular metal film 40 excluding the notch 41 is constant.

The portion of the annular metal film 40 between the tip end portion (inner peripheral side end portion) of the notch portion 41 and the center hole 42 is an easily broken portion 43. The distance D ₄₀ between the peripheral edges of the annular metal film 40 is locally reduced at the easily broken portion 43.
The notch 41 is a trigger for breakage when electromagnetic induction heating becomes excessive.

The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, the present invention is not limited to the NATM method, but can also be applied to a tunnel construction method using the SENS method or the like. After the fixing discs 20 and 20B are directly fixed to the primary lining 3 with a fixing member such as a concrete nail 32 or an anchor, the waterproof sheet 10 may be stretched from the front side of the fixing discs 20 and 20B. The backside cushioning material 12 of the waterproof sheet 10 may be in direct contact with the induction heating adhesive sheet 22. Then, the hot melt layer 27 may be joined to the back surface cushioning material 12 by electromagnetic induction heating.

Examples will be described. However, the present invention is not limited to the following examples.
A fixed disk 20 having substantially the same shape as that of the first embodiment (FIGS. 1 to 3) was prepared, and the probe 7b of the electromagnetic induction heater 7 was held over the fixed disk 20 for electromagnetic induction heating.
The length of one side of the square outer peripheral edge of the annular metal film 26 of the fixed disk 20 was 85 mm.
The diameter of the center hole 25c was 39 mm.
The material of the annular metal film 26 was aluminum (Al).
The thickness of the annular metal film 26 was 30 μm.
As the electromagnetic induction heater 7, a model number HB-75 manufactured by Brownie Co., Ltd. was used.
The power supply was single layer 200V, 15A.
The output frequency of electromagnetic induction was 20 KHz.
The distance from the probe 7b of the electromagnetic induction heater 7 to the annular metal film 26 was 0.8 mm.

As shown in FIG. 10, when the electromagnetic induction heating time was 4 seconds, a crack 28c was formed from the central portion of one side of the outer peripheral edge of the annular metal film 26 to the center hole 25c.
After that, the induced magnetic field was continuously applied, but the annular metal film 26 cooled down.

The present invention can be applied to tunnel construction by, for example, the NATM method or the SENS method.

1 Tunnel 3 Primary lining (tunnel peripheral wall)
7 Electromagnetic induction heater 7b Probe 10 Waterproof sheet 20, 20B Fixed disk for tunnel waterproof sheet 32 Concrete nail (fixing member)
21 Base 22 Induction heat adhesive sheet 23 Fixing penetration part 25 Adhesive film layer 26 Circular metal film 27 Hot melt layer 28 Easy breaking part 40 Circular metal film 43 Easy breaking part D ₂₆ , D ₄₀ Peripheral distance (inner and outer peripheral edges) Connecting distance)

Claims (4)

A fixed disc for tunnel tarpaulin that fixes the tarpaulin to the peripheral wall of the tunnel.
A base provided with a fixing penetration part through which the fixing member is penetrated,
An annular metal film provided on the surface of the base so as to surround the fixing penetration portion and electromagnetically induced and heated.
A hot melt layer laminated on the surface of the annular metal film, and the like.
A local easily broken portion due to the electromagnetic induction heating is provided at a predetermined position in the circumferential direction of the annular metal film .
The fixing penetration portion includes a tubular portion whose inside is opened on the front side surface facing the inside of the tunnel of the base, and a bottom plate portion that closes the back side end of the tubular portion facing the ground side opposite to the front side surface. A fixed disk for a tunnel waterproof sheet , wherein the bottom plate portion protrudes toward the ground side from a portion of the base other than the fixing penetration portion . The fixed disk for a tunnel waterproof sheet according to claim 1, wherein the distance connecting the inner peripheral edge and the outer peripheral edge at various points in the circumferential direction of the annular metal film is locally small at the easily broken portion. The fixing disk for a tunnel waterproof sheet according to claim 1 or 2, wherein the outer peripheral edge of the annular metal film is quadrangular, and the inner peripheral edge of the annular metal film is circular. The fixed disk for a tunnel waterproof sheet according to any one of claims 1 to 3, wherein the thickness of the annular metal film is 10 μm to 100 μm.

Images