Metal formwork and movable arch of tunnel

Abstract

To improve quality of lining concrete.SOLUTION: A metal formwork which forms a space for pouring lining concrete between itself and an inner circumferential surface of a tunnel comprises: an outer frame 31 which faces the inner circumferential surface of the tunnel; web plates 32 which extend from both ends of the outer frame in the tunnel extension direction toward the inside of the tunnel; reinforcing members 33 which are arranged at intervals in the circumferential direction on the tunnel-inner side of the outer frame, which extend in the tunnel extension direction, and which are connected to the web plate at one end and the web plate at the other end; a plurality of heating members 5 which are intermittently installed on exposed surfaces on the tunnel-inner side of the outer frame arranged in the circumferential direction with the reinforcing members between them, and which heat the lining concrete via the outer frame; a thermal insulation coating film 6 which is formed in a first region Z1 of the exposed surface where no heating members are installed, and which contains a thermal insulation material 62 as an additive; and a rust prevention coating film 60 which is formed in a second region Z2 of the exposed surface where the heating members are installed, and which contains a rust prevention material 61 as a base and either does not contain a thermal insulation material as an additive or has a lower content of the thermal insulation material than the thermal insulation coating film.SELECTED DRAWING: Figure 13

Description

Technical Field

[0001] The present invention relates to a metal formwork and a mobile centering for placing covering concrete.

Background Art

[0002] The covering concrete of a tunnel is placed in predetermined sections using a metal formwork provided on a slide centering movable in the tunnel extension direction. In order to prevent the covering concrete from cracking when demolding the placed covering concrete, it is necessary to increase the compressive strength of the covering concrete.

[0003] The applicant of the present application has previously proposed a technique for obtaining a desired compressive strength by heating the covering concrete from the completion of placing the covering concrete to demolding (see Patent Document 1 below). The mobile centering described in Patent Document 1 includes a heater unit for heating the covering concrete.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] When demolding, peeling may occur on the inner peripheral surface of the covering concrete. FIG. 15 is a schematic diagram showing an example of the inner peripheral surface of the covering concrete where peeling has occurred. The peeling shown in FIG. 15 may occur even when the covering concrete is heated. In order to improve the quality of the covering concrete, a measure for preventing peeling of the covering concrete is desired.

[0006] The present invention has been made in view of such circumstances, and an object thereof is to provide a metal formwork and a mobile centering that can further improve the quality of the covering concrete.

Means for Solving the Problems

[0007] (1) The present invention is a metal formwork that forms a placing space for covering concrete between the inner peripheral surface of a tunnel, and includes an outer frame facing the inner peripheral surface of the tunnel, webs extending from both ends of the outer frame in the tunnel extension direction toward the inside of the pit, reinforcing members arranged at intervals in the circumferential direction on the inside of the pit of the outer frame, extending in the tunnel extension direction, and connected to the web on one end side and the web on the other end side, and a plurality of heating members intermittently installed on the exposed surfaces on the inside of the pit of the outer frame arranged in a plurality in the circumferential direction with the reinforcing members interposed therebetween, for heating the covering concrete through the outer frame, a heat insulation coating film formed in a first region of the exposed surface where the heating members are not installed, containing a heat insulation material as an additive, and a rust preventive coating film formed in a second region of the exposed surface where the heating members are installed, containing a rust preventive material as a base and not containing a heat insulation material as an additive or having a lower content rate of the heat insulation material than the heat insulation coating film.

[0008] According to the present invention, by forming a heat insulation coating film on the exposed surface on the inside of the pit of the outer frame where heat easily escapes, the heat of the covering concrete is less likely to escape to the inside of the pit, and the quality of the covering concrete can be further improved. Also, by concentrating the formation of the heat insulation coating film in the region where heat easily escapes, the heat insulation property of the metal formwork can be ensured while reducing the amount of heat insulation material used. Thereby, the workability can be improved or the material cost for construction can be reduced.

[0009] (2) The heat insulation coating film contains a rust preventive material as a base and a heat insulation material as an additive, and the heat insulation material may contain wood chips or fly ash.

[0010] Both wood chips and fly ash are by-products and were discarded as industrial waste if not utilized. According to the present invention, since wood chips and fly ash can be utilized as renewable resources for a new use (heat insulating material), the environmental load can be reduced while improving the heat insulating performance of the metal formwork.

[0011] (3) The heat insulating coating may contain fly ash at a concentration of 40% by volume or more and 50% by volume or less with respect to the rust preventive material.

[0012] When fly ash is added to the rust preventive material at a concentration exceeding 50% by volume, it may cause problems with the adhesion stability of the heat insulating coating. On the other hand, in order to enhance the heat insulating performance, it is preferable to add the maximum amount of fly ash as the heat insulating material within the range where the state after coating such as adhesion stability is good. According to the present invention, since fly ash is contained at a concentration of 40% by volume or more and 50% by volume or less with respect to the rust preventive material, higher heat insulating performance can be obtained while maintaining the adhesion stability.

[0013] (4) The reinforcing member has a plurality of welded portions welded to the outer frame or the web, and the welded portions may not be formed at the portion of the reinforcing member that contacts both the outer frame and the web.

[0014] By configuring in this way, the heat of the outer frame is less likely to be transmitted to the web than before, and the peeling of the covering concrete can be suppressed. As a result, the quality of the covering concrete can be further improved.

[0015] (5) The first circumferential end of the reinforcing member facing the first region has a plurality of first welded portions welded to the outer frame, and the second circumferential end of the reinforcing member facing the second region has a plurality of second welded portions welded to the outer frame. The shortest distance between the plurality of first welded portions and the web may be longer than the shortest distance between the plurality of second welded portions and the web.

[0016] According to the present invention, by separating the first welding part where heat easily escapes from the web where heat easily escapes, it is possible to avoid the concentration of the first welding part at a position where heat easily escapes. As a result, the heat of the outer frame is less likely to be transmitted to the web than in the prior art, peeling of the covering concrete can be suppressed, and the quality of the covering concrete can be further improved.

[0017] (6) The plurality of second welding parts may be formed at positions that do not overlap with the plurality of first welding parts in the circumferential direction.

[0018] By configuring in this way, it is possible to disperse the easily-cooled positions (welding positions) of the metal formwork. Thereby, peeling of the covering concrete can be suppressed, and the quality of the covering concrete can be further improved.

[0019] (7) The total length in the tunnel extension direction of the plurality of first welding parts may be shorter than the total length in the tunnel extension direction of the plurality of second welding parts.

[0020] According to the present invention, it is possible to suppress the heat of the outer frame from escaping to the reinforcing member through the first welding part where heat easily escapes. Also, by making the total length of the second welding parts where heat hardly escapes longer, the joining strength between the outer frame and the reinforcing member can be maintained.

[0021] (8) The metal formwork of the present invention is a metal formwork that forms a placing space for covering concrete between it and the inner peripheral surface of the tunnel, and includes an outer frame facing the inner peripheral surface of the tunnel, webs extending from both ends of the outer frame in the tunnel extension direction toward the inside of the pit, reinforcing members arranged at intervals in the circumferential direction on the inside of the pit of the outer frame and extending in the tunnel extension direction and connected to the web on one end side and the web on the other end side, the reinforcing member having a plurality of welding parts welded to the outer frame or the web, and the welding parts are not formed at the portion of the reinforcing member that contacts both the outer frame and the web.

[0022] According to the present invention, heat from the outer frame is less likely to be transmitted to the web than before, and peeling of the covering concrete can be suppressed. As a result, the quality of the covering concrete can be further improved.

[0023] (9) The movable centering of the present invention is a movable centering with a total extension of 10.5 m, in which the length of the metal formwork in the tunnel extension direction among any of the above (1) to (8) is 2.1 m, and five of the metal formworks are joined in the tunnel extension direction.

[0024] By using a movable centering with 5 spans of 2.1 m, the number of webs is less than that of a conventional movable centering with 7 spans of 1.5 m, so the amount of heat escaping from the heated covering concrete through the webs can be reduced. As a result, in response to the reduction in the number of webs, peeling of the covering concrete at the time of demolding is suppressed, and thus the quality of the covering concrete can be further improved.

Effects of the Invention

[0025] According to the present invention, the quality of the covering concrete can be further improved.

Brief Description of the Drawings

[0026]

Figure 1

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Figure 13

Figure 14

Figure 15

Modes for Carrying Out the Invention

[0027] 〔Regarding the Causes and Countermeasures of Peeling〕 The present inventor has intensively studied countermeasures for preventing the peeling of the shotcrete exemplified in FIG. 15. In the process, it has been found that such peeling is particularly likely to occur during winter construction.

[0028] In addition, as types of peeling marks, as shown in FIG. 15, there are a first peeling mark A1 extending in the circumferential direction, a second peeling mark A2 extending in the tunnel extension direction starting from the first peeling mark A1, and a third peeling mark A3 located at points on the virtual extension line of the second peeling mark A2. It has been discovered that the formation positions of these correspond to the positions of the web, the positions of the reinforcing members, and the positions where the reinforcing members and the outer frame are welded among the components of the formwork, respectively.

[0029] From this, the inventor considered that the cause of the peeling of the covering concrete during demolding was that the heat of the covering concrete was locally cooled by the formwork, resulting in insufficient heating of the covering concrete. Therefore, the inventor proposes an invention to improve the heat insulation performance of the formwork in this application. According to the present invention, it is possible to suppress the peeling of the covering concrete during demolding and improve the quality of the covering concrete.

[0030] Specifically, in the present invention, the following measures are taken to improve the heat insulation performance of the formwork. (1) Increase the span length of the formwork and reduce the number of webs. (2) Reduce the contact area between the outer frame and the reinforcing member, and provide a closed space between the outer frame and the reinforcing member. (3) Form a heat insulation coating film on the exposed surface inside the pit of the outer frame. (4) Provide welding parts so that the welding positions of the reinforcing members do not concentrate on positions where heat easily escapes.

[0031] Hereinafter, an embodiment including all of the above measures (1) to (4) will be described with reference to the drawings. In the present invention, at least one of the above measures (1) to (4) may be taken, and it is not essential to include all of them.

[0032] 〔Overall Configuration of the System〕 FIG. 1 is a diagram showing the overall configuration of a construction system for covering concrete according to an embodiment of the present invention. The construction system is a system for constructing secondary covering concrete C1 (hereinafter, also simply referred to as "covering concrete C1") on the inner peripheral surface (inner wall) t1 of a once-covered tunnel T1. The construction system includes a slide centering device 1 (mobile centering device) for placing the covering concrete C1 and a plurality of curing devices 10 for curing the covering concrete C1 placed by the slide centering device 1.

[0033] The slide centering device 1 and the curing device 10 are capable of traveling on the rail R1 laid on the floor surface in the tunnel T1. The slide centering device 1 sequentially places the lining concrete C1 at a predetermined span from the portal side toward the face side (in the direction of the arrow in FIG. 1). The curing device 10 sequentially cures the placed lining concrete C1 at a predetermined span.

[0034] 〔Configuration of Slide Centering Device〕 FIG. 2 is a front view of the slide centering device 1. FIG. 3 is a cross-sectional view of the slide centering device 1 cut along the cutting line III in FIG. 2. In FIGS. 2 and 3, for simplicity of the drawing, the description of the heating member 5 and the heat insulation coating 6 described later is omitted. Also, in FIG. 3, the description of the reinforcing member 33 described later is omitted.

[0035] The slide centering device 1 includes a gantry carriage 2 capable of traveling in the tunnel T1 and a plurality of metal formworks 3 (hereinafter simply referred to as "formworks 3") that serve as weir plates for molding the inner peripheral surface of the lining concrete C1.

[0036] The gantry carriage 2 includes a base portion 2a and a plurality of support columns 2b that support the base portion 2a. At the lower end of the support column 2b, wheels 2c that engage with the rail R1 laid on the floor surface of the tunnel T1 are provided, and the gantry carriage 2 travels in the tunnel T1 by the rolling of these wheels 2c along the rail R1.

[0037] The formwork 3 has a cross-sectional arc shape substantially along the inner peripheral surface t1 of the tunnel T1 and forms a placement space D1 for placing the lining concrete C1 between it and the inner peripheral surface t1 of the tunnel T1. The formwork 3 is also referred to as a centering form. As shown in FIG. 2, the formwork 3 includes a top end portion 3a that covers the crown of the inner peripheral surface t1, side portions 3b that are rotatably connected to both ends of the top end portion 3a and cover the upper part of the side wall of the inner peripheral surface t1, and a lower end portion 3c that is rotatably connected to the lower end of the side portion 3b and covers the lower part of the side wall of the inner peripheral surface t1.

[0038] The top end portion 3a is supported so as to be vertically movable by a plurality of jacks 41 provided on the base portion 2a of the gantry carriage 2. The side portions 3b and the lower end portion 3c are respectively supported so as to be rotatable in the width direction by a plurality of jacks 42 and 43 provided on the outer surface of the support column 2b. The top end portion 3a, the side portions 3b, and the lower end portion 3c each have a placing port (not shown) for pouring fresh concrete into the placing space D1.

[0039] Refer to FIG. 3. In the present embodiment, a slide centering device 1 with a standard length of 10.5 m is configured by connecting a plurality of formworks 3 in the tunnel extension direction. Here, in a conventional slide centering device (for example, FIG. 3 of Japanese Patent Laid-Open No. 2011-190594), when adopting a standard length of 10.5 m, the formwork is divided into 7 parts in the tunnel extension direction, and a formwork with a length in the tunnel extension direction of one formwork (that is, the span length) of 1.5 m, namely, a "7-span 1.5 m" formwork is used.

[0040] On the contrary, in the present embodiment, a slide centering device 1 with a total extension of 10.5 m is configured by connecting 5 formworks 3 with a span length of 2.1 m. That is, the slide centering device 1 of the present embodiment is "5-span 2.1 m", which is 2 spans less than the conventional type. With this configuration, the number of webs 32 described later is less than that of the conventional one, so that the amount of heat escaping from the heated lining concrete C1 through the web 32 can be reduced.

[0041] As a result, in response to the reduction in the number of webs 32, the peeling of the lining concrete at the time of demolding is suppressed, and the number of the first peeling marks A1 in FIG. 15 is reduced. Thereby, the quality of the lining concrete C1 can be further improved.

[0042] In addition, with the configuration of making the slide centering device 1 have 2 spans less than the conventional type, the number of trucks required for transporting the formwork 3 can be reduced, and the transportation cost can be reduced.

[0043] FIG. 14 is a schematic diagram showing a state where the divided formwork is loaded on a truck. Figs. 14(a) and (b) are a plan view and a side view showing a state in which a part of the formwork 3 with a span length of 2.1 m (two side portions 3b are illustrated in the figure) is loaded on the loading platform B1 of the truck Tr1. A part of the formwork 3 is clamped to the truck Tr1, for example, in a state where the tunnel extension direction is set vertically. Similarly, it is clamped in the case of the conventional span length of 1.5 m.

[0044] The truck Tr1 is, for example, a 10t truck, and the height of the loading platform B1 is about 1.5 m from the ground. The loading height of the truck is generally regulated to be 3.8 m or less. Since the formwork 3 divided using the truck Tr1 can be accommodated within the regulated height when the span length is 2.1 m, the formwork 3 can be transported from the factory to the tunnel T1 using the truck Tr1.

[0045] When the number of spans is 4 or less, the span length becomes 2.6 m or more (10.5÷4 = 2.625), and the loading height becomes 4.1 m or more (1.5 + 2.625 = 4.125 m). Therefore, it exceeds the regulated height, which may hinder the transportation of the formwork 3. For this reason, as the number of spans, 5, which gives the maximum span length within the range where transportation by truck is possible, is particularly preferable. If the transportation problem can be solved, in the implementation of the present invention, the number of spans of 4 or less may be adopted, or the number of spans of 6 may be adopted.

[0046] Furthermore, by configuring the slide center 1 to have two spans less than the conventional type, the number of parts of the slide center 1 is reduced compared to the conventional one. Therefore, the manufacturing cost of the slide center 1 can be reduced, and the time required for assembling and disassembling the slide center 1 can be shortened. For example, in the case of a 7-span 1.5 m slide center, it takes, for example, 9 trucks for transportation, 6 days for assembly work, and 4 days for disassembly work. In the case of the 5-span 2.1 m slide center 1, the number of trucks required for transportation can be set to 7, the assembly work can be set to 5 days, and the disassembly work can be set to 3 days.

[0047] 〔Configuration of formwork〕 FIG. 4 is a perspective view of a part of the side portion 3b of the formwork 3 as viewed obliquely from above. Hereinafter, the side portion 3b will be representatively described for the formwork 3, and the other parts (the top end portion 3a and the bottom end portion 3c) of the formwork 3 have the same configuration as the side portion 3b, so the description thereof will be omitted. The side portion 3b of the formwork 3 includes an outer frame 31, a pair of webs 32, and a plurality of (for example, seven) reinforcing members 33.

[0048] The outer frame 31 is a metal (for example, steel) plate material extending in the tunnel extension direction and the circumferential direction, and faces the inner circumferential surface t1 of the tunnel T1 when the lining concrete C1 is placed.

[0049] The webs 32 are metal (for example, steel) plate materials extending inward from both ends of the outer frame 31 in the tunnel extension direction. The webs 32 have a function of supporting the outer frame 31 and are also referred to as webs.

[0050] The reinforcing members 33 are metal (for example, steel) members for reinforcing the inside of the outer frame 31 in the pit and are also referred to as stiffening members. The reinforcing members 33 are provided on the inside of the outer frame 31 in the pit, extend in the tunnel extension direction, and are connected to the web 32 on one end side and the web 32 on the other end side. A plurality of the reinforcing members 33 are arranged at intervals in the circumferential direction on the inside of the outer frame 31 in the pit.

[0051] FIG. 5 is a cross-sectional view of the side portion 3b of the formwork 3 cut along the cutting line V in FIG. 4. The reinforcing member 33 has a trapezoidal cross section and forms a closed space S1 between it and the outer frame 31. The reinforcing member 33 includes a first wall portion 33a extending from the outer frame 31 inward into the pit, a second wall portion 33b extending from the outer frame 31 inward into the pit adjacent to the first wall portion 33a in the circumferential direction, and a third wall portion 33c connected to the first wall portion 33a and the second wall portion 33b and facing the outer frame 31 with a gap therebetween.

[0052] The inner surface of the outer frame 31 on the inside of the pit includes an exposed surface 31a exposed in the pit and a covered surface 31b that forms the closed space S1 by being covered by the reinforcing member 33. A plurality of the exposed surfaces 31a are arranged side by side in the circumferential direction with the reinforcing members 33 interposed therebetween. In the case of the side portion 3b of the present embodiment, eight exposed surfaces 31a are arranged side by side in the circumferential direction with seven reinforcing members 33 interposed therebetween.

[0053] As shown by the second peeling mark A2 in Fig. 15, the heat of the covering concrete C1 tends to easily escape from the portion where the outer frame and the reinforcing member are connected toward the inside of the pit. In the present embodiment, by making the cross-sectional shape of the reinforcing member 33 a hollow structure, the contact area between the outer frame 31 and the reinforcing member 33 can be reduced as compared with the case of using a solid-structured reinforcing member. Thereby, it is possible to suppress the heat of the covering concrete C1 from escaping toward the inside of the pit through the outer frame 31 and the reinforcing member 33.

[0054] Further, since a closed space S1 is formed between the outer frame 31 and the reinforcing member 33, the heat of the covering surface 31b of the outer frame 31 is insulated by the air in the closed space S1, and it is possible to further suppress the heat from being transmitted to the reinforcing member 33. As a result, the heat of the covering concrete C1 is less likely to escape to the inside of the pit, and the occurrence of the second peeling mark A2 in Fig. 15 can be suppressed. Thereby, the quality of the covering concrete C1 can be further improved.

[0055] 〔Regarding the heating member〕 Refer to Figs. 4 and 5. The side portion 3b of the formwork 3 further includes a plurality of heating members 5. The heating members 5 are intermittently installed with respect to the plurality of exposed surfaces 31a. In the present embodiment, the heating members 5 are installed every other one with respect to the plurality of exposed surfaces 31a. Note that the heating members 5 may be intermittently installed with respect to at least some of the exposed surfaces 31a, or may be continuously installed on a plurality of adjacent exposed surfaces 31a in the circumferential direction.

[0056] As shown in Fig. 4, the heating member 5 includes a planar heating element 51 that generates heat when energized, and an electric wire 52 that supplies power to the heating element 51. The electric wire 52 passes through the through-hole 32a in the tunnel extension direction of the web 32 and is connected to a power source (not shown). The heating member 5 heats the covering concrete C1 through the outer frame 31 when the covering concrete C1 is placed, so as to obtain a predetermined compressive strength for the covering concrete C1.

[0057] Incidentally, instead of the heating element 51 and the electric wire 52, the heating member 5 may have a pipe through which a heat medium of a liquid (such as water or oil) circulates. In this case, the heat medium is heated by a heating device such as a boiler and pumped into the pipe by a pump.

[0058] By intermittently installing the heating member 5, the number of heating members 5 can be reduced. As a result, the member cost and the energy cost for operating the heating member 5 can be lowered. On the other hand, when the heating member 5 is installed intermittently, the heat of the formwork concrete C1 escapes easily from the exposed surface 31a where the heating member 5 is not installed to the inside of the pit. For this reason, in the present embodiment, by providing the heat insulation coating film 6 described later on the exposed surface 31a, more heat is retained in the formwork concrete C1.

[0059] 〔Regarding the heat insulation coating film〕 Referring to FIG. 5, the side portion 3b of the formwork 3 further includes a heat insulation coating film 6. The heat insulation coating film 6 is formed on the entire inner surface of the side portion 3b including the exposed surface 31a of the outer frame 31. The heat insulation coating film 6 includes a rust preventive material 61 as a base and a heat insulation material 62 as an additive.

[0060] The rust preventive material 61 is a known rust preventive paint, for example, "Quick-drying Rust Preventive Eco" manufactured by Nippon Paint Co., Ltd.

[0061] The heat insulation material 62 includes, for example, wood chips or fly ash. Note that the heat insulation material 62 is not limited to this, and other heat insulation materials may be included. As the heat insulation material, for example, a material having a particle size of several tens of μm to several hundreds of μm and having a hollow structure or a porous structure is preferable. As other heat insulation materials, for example, hollow glass beads may be included.

[0062] When fly ash is used as the heat insulation material 62, the heat insulation coating film 6 contains, for example, fly ash at a concentration of 40% by volume or more and 50% by volume or less. That is, the heat insulation material 62 is added so that the volume of the heat insulation material 62 is about 70 to 90 with respect to 100 volumes of the rust preventive material 61.

[0063] When fly ash is added to the rust preventive material 61 in a concentration exceeding 50% by volume, it may cause problems with the adhesion stability of the heat insulating coating film 6 (for example, the heat insulating coating film 6 becomes more likely to peel off). On the other hand, in order to enhance the heat insulating performance, it is preferable to add the maximum amount of fly ash as the heat insulating material 62 within a range where the state after application such as adhesion stability is good. In the present embodiment, a concentration near 50% by volume is more suitable. Note that if the state after application is good, fly ash may be added to the rust preventive material 61 in a concentration exceeding 50% by volume.

[0064] Wood chips are, for example, powdery "sawdust" or "shavings" generated when cutting wood. The particle size of the wood chips is, for example, about 200 μm. Conventionally, wood chips have been used as cushioning materials for transported goods, bedding materials for livestock, etc. However, the present inventor focused on the heat insulating performance of wood and newly conceived adding wood chips as the heat insulating material 62 to the rust preventive material 61.

[0065] Fly ash is fine particles of ash generated when burning coal in coal-fired power generation, etc. The particle size of fly ash is, for example, about 10 μm or more and 100 μm or less. Conventionally, fly ash has been used as a concrete additive for imparting strength and fluidity to concrete. However, the present inventor focused on the fact that fly ash is porous and has heat insulating performance, and newly conceived adding fly ash as the heat insulating material 62 to the rust preventive material 61.

[0066] Both wood chips and fly ash are by-products and were discarded as industrial waste when not utilized. According to the heat insulating coating film 6 of the present embodiment, wood chips and fly ash can be utilized as recycled resources for a new use (heat insulating material), so that the environmental load can be reduced while improving the heat insulating performance of the formwork 3. As a result, the heat of the covering concrete C1 is less likely to escape to the pit side through the formwork 3, and the quality of the covering concrete C1 can be further improved.

[0067] 〔Experimental examples of heat insulating coating film〕 In order to confirm the effect of using wood chips or fly ash as the heat insulating material 62 of the heat insulating coating film 6, the inventor of the present invention conducted the experiment described below.

[0068] FIG. 6 is a schematic diagram showing an experimental example of a heat insulating coating film. Five types of coating films X1 to X5 were respectively applied to one side of a steel material Y1 having a thickness of 6 mm, and five samples were prepared in which a heat source H1 (resistance heating heater) was respectively attached to the other side of the steel material Y1. Three sensors P1 to P3 for detecting temperature were respectively installed on the coating films X1 to X5. Sensor P1 was installed directly behind the heat source H1, sensor P2 was installed at a position 7 cm away from the center of sensor P1, and sensor P3 was installed at a position 10 cm away from the center of sensor P2.

[0069] The temperature of the heat source H1 was set to 60° C., and the heat transmitted from the heat source H1 to the sensors P1 to P3 through the steel material Y1 and the coating films X1 to X5 was measured. Thereby, the heat escaping to the inside of the pit from the heated covering concrete C1 (simulated by the heat source H1) through the outer frame 31 (simulated by the steel material Y1) and the heat insulating coating film 6 (simulated by the coating films X1 to X5) was evaluated by the measured temperatures of the sensors P1 to P3.

[0070] FIG. 7 is a table showing the coating films used in the experiment. Coating film X1 is a simple rust preventive coating film that contains a rust preventive material as a base and does not contain a heat insulating material as an additive, and is a reference example of this experiment. As the rust preventive material, "Quick-drying Rust Preventive Eco" manufactured by Nippon Paint Co., Ltd. was used. The same rust preventive material as that of coating film X1 was also used as the base of coating films X2 to X4.

[0071] Coating film X2 contains a rust preventive material as a base and wood chips as an additive. The volume of the wood chips was added so as to be about 50 with respect to 100 of the volume of the rust preventive material (concentration of about 33% by volume).

[0072] Coating film X3 contains a rust preventive material as a base and fly ash as an additive. The volume of the fly ash was added so as to be about 80 with respect to 100 of the volume of the rust preventive material (concentration of about 44% by volume).

[0073] Coating film X4 contains a rust preventive material as a base and "heat cut powder" manufactured by Toa System Create Co., Ltd. as an additive. The heat cut powder was added so that its volume would be approximately 80 with respect to a volume of 100 of the rust preventive material (concentration of approximately 44% by volume). Since the heat cut powder is a ceramic powder and is an additive that has been conventionally used for heat insulation applications, it was prepared as a comparative example.

[0074] Coating film X5 is "heat insulation coat" manufactured by East Japan Paint Co., Ltd. The heat insulation coat is a heat insulation paint in which a heat insulation pigment and the like are added to an acrylic silicone resin, and it was prepared as a comparative example.

[0075] Coating films X1 to X4 were each formed by one spray application. Coating film X5 was spray applied three times while sandwiching the overcoatable time according to the specifications.

[0076] The film thicknesses of coating films X1 to X5 were measured with a coating film thickness gauge. The film thickness of coating film X1 was 100 μm, and the film thicknesses of coating films X2, X3, and X4 were 412 μm, 373 μm, and 508 μm, respectively. In coating films X2, X3, and X4, granular additives of several tens of μm to several hundreds of μm were added to the rust preventive material, respectively, so the film thickness became thicker than that of coating film X1. The film thickness of coating film X5 was 983 μm, and the film thickness became the thickest due to overcoating.

[0077] Figure 8 is a graph showing the results of the experiment. The horizontal axis of the graph indicates the elapsed time [minutes] from the start of heating of heat source H1, and the vertical axis of the graph indicates the temperature [°C]. The upper line group of the graph is the measured temperature of sensor P1, the middle line group of the graph is the measured temperature of sensor P2, and the lower line group of the graph is the measured temperature of sensor P3. The tendency that the measured temperature of sensor P1, which is closer to heat source H1, is the highest and the measured temperature of sensor P3, which is farther from heat source H1, is the lowest is common to all of coating films X1 to X5.

[0078] Here, attention is paid to the temperature difference (Tp1 - Tp3) between the measured temperature Tp1 of sensor P1 and the measured temperature Tp3 of sensor P3 at a predetermined elapsed time. On the graph, this temperature difference is represented by, for example, arrow AR1. The larger this temperature difference, the less heat is transferred to sensor P3, meaning that the heat insulation performance of the coating film is high. The temperature difference at an elapsed time of 25 minutes is shown in the right column of the table in Fig. 7.

[0079] As shown in Fig. 7, the temperature differences are 20.6°C for coating film X2 (wood chip) and 22.3°C for coating film X3 (fly ash), as compared with 17.8°C for coating film X1 (rust preventive coating), which is a reference example. Higher heat insulation performance than the reference example was obtained in both the wood chip and fly ash cases.

[0080] Also, the temperature differences of coating films X2 and X3 are higher than 16.0°C for coating film X4 (heat cut powder), which is a comparative example, and 17.8°C for coating film X5. It was confirmed that coating films X2 and X3 have higher heat insulation performance than coating films X4 and X5, which have conventionally been used as heat insulation materials. From the above, the heat insulation coating film 6, which is based on the rust preventive material 61 and has wood chip or fly ash added as the heat insulation material 62, has suitable heat insulation performance.

[0081] 〔Regarding the welding position of the reinforcing member〕 Fig. 9 is a side view of a part of the side portion 3b of the formwork 3 as seen from the inside of the pit. Fig. 10 is a schematic diagram for explaining a comparative example of the welding position. Hereinafter, with reference to Figs. 5, 9, and 10, the welding position of the reinforcing member 33 will be described.

[0082] First, a comparative example of the welding position will be described. Fig. 10(a) is a view of the side portion 3b according to the comparative example in the same cross section as Fig. 5, and Fig. 10(b) is a view of the side portion 3b according to the comparative example from the same direction as Fig. 9. In the comparative example, the reinforcing member 33 is tap-welded to the web 32 by a plurality of welded portions 81a, 81b, 81c (also simply referred to as "welded portion 81"), and is tap-welded to the outer frame 31 by a plurality of welded portions 82, 83.

[0083] More specifically, the welded portion 81a is formed at a portion where the first wall portion 33a of the reinforcing member 33 contacts both the outer frame 31 and the web 32 (that is, the corner on the outer frame 31 side of the reinforcing member 33). By welding the position where three or more members contact in this way, the reinforcing member 33 can be fixed to both the outer frame 31 and the web 32. Therefore, a welded portion is usually formed at this position.

[0084] Similarly, the welded portion 81b is formed at a portion where the second wall portion 33b of the reinforcing member 33 contacts both the outer frame 31 and the web 32. Further, the welded portion 81c is formed at a portion where the third wall portion 33c of the reinforcing member 33 contacts the web 32.

[0085] The plurality of welded portions 82 are formed at intervals at a portion where the first wall portion 33a of the reinforcing member 33 contacts the outer frame 31. The plurality of welded portions 83 are formed at intervals at a portion where the second wall portion 33b of the reinforcing member 33 contacts the outer frame 31. Normally, the formation intervals of the welded portion 82 and the welded portion 83 are the same, and as shown in FIG. 10(b), the welded portion 82 and the welded portion 83 overlap in the circumferential direction.

[0086] Since the reinforcing member 33, the outer frame 31, and the web 32 are integrated at the welded portions 81 to 83, the heat of the outer frame 31 and the web 32 is particularly easily transmitted to the reinforcing member 33 from the welded portions 81 to 83. That is, the formwork 3 is particularly likely to cool at the welded portions 81 to 83, which is the cause of the formation of the second peeling mark A2 and the third peeling mark A3 in FIG. 15.

[0087] Therefore, in the present embodiment, the position where the welded portion of the reinforcing member 33 is provided is devised so that the welded portion does not concentrate at a position where heat easily escapes, thereby suppressing the peeling of the covering concrete C1.

[0088] Specifically, by the following measures A to D, it is avoided that the welded portion concentrates at a position where heat easily escapes. In the present embodiment, all of the measures A to D are included, but in the present invention, at least one of the measures A to D may be taken, and it is not essential to include all of them.

[0089] 〔Measure A: Move the welded part away from the position where the three points of the reinforcing member, the web, and the outer frame are in contact〕 Refer to the enlarged view of FIG. 5. The reinforcing member 33 of the present embodiment is tapped and welded to the web 32 by a plurality of welded parts 71a, 71b (also simply referred to as "welded part 71"). The welded part 71a is formed at the corner where the first wall part 33a and the third wall part 33c are connected and in the vicinity thereof, and the welded part 71b is formed at the corner where the second wall part 33b and the third wall part 33c are connected and in the vicinity thereof. And the welded parts 71a, 71b are at positions away from the outer frame 31. That is, no welded part 71 is formed at the part of the reinforcing member 33 that contacts both the outer frame 31 and the web 32.

[0090] Since the web 32 is a steel material extending toward the inside of the shaft, it functions like a heat dissipation fin in the formwork 3, and it is easy for the heat of the covering concrete C1 to escape to the inside of the shaft. In the conventional welding method, as shown in FIG. 10, welding is performed at the part of the reinforcing member 33 that contacts both the outer frame 31 and the web 32. Therefore, the heat of the outer frame 31 is easily transmitted to the web 32 through the welded parts 81a, 81b, which is considered to be one of the causes of the second peeling mark A2 in FIG. 15.

[0091] On the other hand, the welded part 71 of the present embodiment is not formed at the part of the reinforcing member 33 that contacts both the outer frame 31 and the web 32. For this reason, the heat of the outer frame 31 is less likely to be transmitted to the web 32 than in the past, and the occurrence of the second peeling mark A2 can be suppressed. Thereby, the quality of the covering concrete C1 can be further improved.

[0092] 〔Measure B: Arrange the welded parts in a staggered pattern〕 Refer to Fig. 9. The reinforcing member 33 of this embodiment is tap-welded to the outer frame 31 at a predetermined interval by a plurality of welding portions 72 (first welding portions) formed on the first wall portion 33a and a plurality of welding portions 73 (second welding portions) formed on the second wall portion 33b. The plurality of welding portions 73 are formed at positions that do not overlap with the plurality of welding portions 72 in the circumferential direction. That is, when viewed in the tunnel extension direction, the welding portion 72 is located between two adjacent welding portions 73, and the welding portions 72 and 73 are arranged in a staggered manner (alternately).

[0093] In the example of Fig. 10, since the easily-cooled welding portions 82 and 83 overlap in the circumferential direction, as shown by the arrow AR2 in Fig. 10, the easily-cooled positions of the formwork 3 are concentrated when viewed in the tunnel extension direction. And it is considered that such a concentration of welding positions contributes to the generation of the third peeling mark A3 in Fig. 15.

[0094] In contrast, since the welding portions 72 and 73 of this embodiment are arranged in a staggered manner, the easily-cooled positions (welding positions) of the formwork 3 are dispersed. Thereby, the generation of the third peeling mark A3 can be suppressed, and the quality of the covering concrete C1 can be further improved.

[0095] 〔Measure C: Move the second welding portion farther from the web than the first welding portion〕 As described above, the heating member 5 of this embodiment is intermittently installed with respect to the plurality of exposed surfaces 31a arranged in the circumferential direction. Here, the region of the exposed surface 31a where the heating member 5 is not installed is referred to as the "first region Z1", and the region of the exposed surface 31a where the heating member 5 is installed is referred to as the "second region Z2". The first wall portion 33a (first end portion) of the reinforcing member 33 faces the first region Z1, and the second wall portion 33b (second end portion) of the reinforcing member 33 faces the second region Z2.

[0096] Since the heating member 5 is not installed in the first region Z1, the first region Z1 becomes colder than the formwork concrete C1 during the heating of the formwork concrete C1, and the heat of the formwork concrete C1 easily escapes from the first region Z1 to the inside of the pit. On the other hand, since the heating member 5 is installed in the second region Z2, the second region Z2 becomes hotter than the formwork concrete C1 during the heating of the formwork concrete C1, and the heat of the formwork concrete C1 hardly escapes from the second region Z2 to the inside of the pit.

[0097] As shown in FIG. 9, the shortest distance between the plurality of welding parts 72 formed on the first wall part 33a and one side web 32 (for example, the right side web 32 in FIG. 9) in the tunnel extension direction is referred to as "shortest distance L1". Since the welding part 72 connects the first region Z1 where the heating member 5 is not installed and the reinforcing member 33, it can be said that it is a welding part (first welding part) from which heat easily escapes. Further, the shortest distance between the plurality of welding parts 73 formed on the second wall part 33b and one side web 32 in the tunnel extension direction is referred to as "shortest distance L2". Since the welding part 73 connects the second region Z2 where the heating member 5 is installed and the reinforcing member 33, it can be said that it is a welding part (second welding part) from which heat hardly escapes.

[0098] In the present embodiment, the shortest distance L1 is longer than the shortest distance L2. In this way, by separating the welding part 72 from which heat easily escapes further from the web 32 from which heat easily escapes, it is possible to configure so that the welding part 72 does not concentrate on the position (near the web 32) where heat easily escapes. As a result, the heat of the first region Z1 becomes less likely to be transmitted to the web 32 than before, and the occurrence of the second peeling mark A2 shown in FIG. 15 can be suppressed.

[0099] 〔Measure D: Making the first welding part shorter than the second welding part〕 Further, the total length in the tunnel extension direction of the plurality of welding parts 72 (first welding parts: welding parts from which heat easily escapes) formed on the first wall part 33a is shorter than the total length in the tunnel extension direction of the plurality of welding parts 73 (second welding parts: welding parts from which heat hardly escapes) formed on the second wall part 33b.

[0100] For example, as shown in FIG. 9, the welding portion 72 is provided in four spots with a predetermined length, while the welding portion 73 is provided in five spots with a predetermined length. Therefore, the sum of the lengths of the plurality of welding portions 72 in the tunnel extension direction is shorter by one spot than the sum of the lengths of the plurality of welding portions 73 in the tunnel extension direction. Note that the number of spots of the welding portions 72 and 73 is an example, and other numbers of spots may also be used.

[0101] Since the sum of the lengths of the plurality of welding portions 72 is short, it is possible to suppress the heat in the first region Z1 from escaping to the reinforcing member 33 through the welding portions 72. Further, by making the sum of the lengths of the plurality of welding portions 73 longer, the joining strength between the outer frame 31 and the reinforcing member 33 can be maintained.

[0102] 〔Modification Example〕 Hereinafter, a modification example of the embodiment will be described. In the modification example, the same components as those in the above-described embodiment are denoted by the same reference numerals, and the description thereof will be omitted as appropriate.

[0103] 〔Modification Example 1 of Reinforcing Member〕 FIG. 11 is a view showing a reinforcing member according to a modification example. The reinforcing member 33 in the above-described embodiment has a trapezoidal cross section and forms a closed space S1 between the outer frame 31. However, the cross-sectional shape of the reinforcing member is not limited to a trapezoid.

[0104] The reinforcing member may be a reinforcing member 34 having a rectangular cross section as shown in FIG. 11(a), or a reinforcing member 35 having a triangular (V-shaped) cross section as shown in FIG. 11(b), or a reinforcing member 36 having an arc-shaped (U-shaped) cross section as shown in FIG. 11(c). For any of these reinforcing members 34 to 36, since a closed space S1 is formed between the outer frame 31 and the reinforcing member 33, it becomes difficult for the heat of the covering concrete C1 to escape to the inside of the pit, and the generation of the second peeling mark A2 in FIG. 15 can be suppressed.

[0105] Further, the reinforcing member may be composed of a plurality of members as in the reinforcing member 37 shown in FIG. 11(d). The reinforcing member 37 is constituted by, for example, welding a first member 37a having a rectangular cross section and a second member 37b having a flat plate-shaped cross section. The first member 37a is fixed to the outer frame 31 so that the rectangular opening faces downward, and the second member 37b is fixed to the outer frame 31 so as to close the opening of the first member 37a.

[0106] Since a closed space S2 is formed between the first member 37a and the second member 37b, the heat transmitted from the outer frame 31 to the outer frame 31 side of the reinforcing member 37 is insulated by the air in the closed space S2, and it is possible to suppress the heat from being transmitted to the inside of the shaft of the reinforcing member 37. As a result, the heat of the covering concrete C1 is less likely to escape to the inside of the shaft, and the occurrence of the second peeling mark A2 in FIG. 15 can be suppressed.

[0107] 〔Modification Example 2 of Reinforcing Member〕 FIG. 12 is a view showing a metal formwork 300 according to a modification example. The metal formwork 300 of this modification example is different from the above-described embodiment in that it has a reinforcing member 38 instead of the reinforcing member 33 of the formwork 3 according to the above-described embodiment, and the other points are the same.

[0108] In the above-described embodiment, by combining the formation of the closed space S1 in the reinforcing member 33 and the formation of the heat insulating coating film 6 on the entire inner surface of the side portion 3b including the exposed surface 31a of the outer frame 31, the heat of the covering concrete C1 is more reliably suppressed from escaping to the inside of the shaft. However, the heat insulation of the formwork 3 may be mainly achieved by the heat insulating coating film 6 without providing a closed space in the reinforcing member.

[0109] The reinforcing member 38 has a rectangular cross section with an opening facing downward, similar to the first member 37a described above. The opening of the reinforcing member 38 is not closed, and a closed space is not formed in the reinforcing member 38. The heat insulating coating film 6 is formed on the entire inner surface of the formwork 300 including the exposed surface 31a of the outer frame 31 and the reinforcing member 38. The composition of the heat insulating coating film 6 is the same as that in the above-described embodiment.

[0110] Even with such a configuration, since the heat of the formwork concrete C1 can be suppressed from escaping to the mine side by the heat insulating coating film 6, the quality of the formwork concrete C1 can be further improved.

[0111] 〔First Modification Example of Heat Insulating Coating Film〕 FIG. 13 is a view showing a metal formwork 301 according to a modification example. The metal formwork 301 of this modification example is different from the above-described embodiment in that it has a rust preventive coating film 60 instead of a part of the heat insulating coating film 6 of the formwork 3 according to the above-described embodiment, and the other points are common.

[0112] In the above-described embodiment, the heat insulating coating film 6 is formed on the entire inner surface of the formwork 3 including the exposed surface 31a of the outer frame 31 and the reinforcing member 38. However, the heat insulating coating film 6 only needs to be formed on at least a part of the exposed surface 31a, and does not necessarily need to be formed on the entire inner surface of the formwork 3 on the mine side.

[0113] The heat insulating coating film 6 is, for example, spray-coated on the inner surface of the formwork 3 on the mine side. The particle size of the heat insulating material 62 (for example, wood chips or fly ash) is larger than the particle size of the rust preventive material 61. For this reason, when the heat insulating coating film 6 containing the heat insulating material 62 is spray-coated, it may be necessary to frequently maintain the spray nozzle. For this reason, it may be easier to construct by forming the heat insulating coating film 6 only on the portion where heat insulation is particularly required, and forming the rust preventive coating film 60 using only the rust preventive material 61 without adding the heat insulating material 62 in the portion where the necessity of heat insulation is low.

[0114] Therefore, in this modification example, as shown in FIG. 13, the heat insulating coating film 6 is formed in the first region Z1 (region where heat easily escapes) of the exposed surface 31a where the heating member 5 is not installed, and the rust preventive coating film 60 is formed in the second region Z2 (region where heat hardly escapes) of the exposed surface 31a where the heating member 5 is installed. The rust preventive coating film 60 of this modification example is a coating film containing the rust preventive material 61 as a base and not containing the heat insulating material 62 as an additive.

[0115] Moreover, since the third region Z3 where the reinforcing member 33 is located suppresses the heat of the outer frame 31 from escaping into the inner river due to the closed space S1, it can be said that it is a region where heat hardly escapes. Therefore, the third region Z3 also mainly forms the rust preventive coating film 60 instead of the heat insulating coating film 6. In addition, a heat insulating coating film 6 is formed in a portion of the third region Z3 that is circumferentially adjacent to the first region Z1 where heat hardly escapes, in order to more reliably insulate heat. Note that the heat insulating coating film 6 may be formed over the entire third region Z3.

[0116] By configuring in this way, by concentrating the heat insulating coating film 6 in the region where heat easily escapes, while ensuring the heat insulation property of the formwork 301, by reducing the usage amount of the heat insulating material 62, the maintenance frequency of the spray nozzle can be reduced, and the workability can be improved. In addition, by reducing the usage amount of the heat insulating material 62, the material cost of the heat insulating coating film 6 can also be reduced.

[0117] Furthermore, by forming the rust preventive coating film 60 instead of the heat insulating coating film 6 in the second region Z2 where heat is input from the heating member 5 to the outer frame 31, the heat input efficiency from the heating member 5 to the outer frame 31 is improved, so that the formwork concrete C1 can be heated more efficiently. As a result, the quality of the formwork concrete C1 can be further enhanced.

[0118] Note that the rust preventive coating film 60 may be a coating film containing the rust preventive material 61 as a base and containing the heat insulating material 62 as an additive at a content rate lower than that of the heat insulating coating film 6. For example, when the heat insulating coating film 6 contains the heat insulating material 62 at a concentration of 50% by volume with respect to the rust preventive material 61, the rust preventive coating film 60 may contain the heat insulating material 62 at a concentration of 25% by volume, which is half of that.

[0119] Even in this case, since the usage amount of the heat insulating material 62 is reduced, effects such as improvement in workability and reduction in material cost can be obtained, and since the rust preventive coating film 60 has lower heat insulation performance than the heat insulating coating film 6, the heat input efficiency from the heating member 5 to the outer frame 31 can be improved.

[0120] Note that the content ratio of the heat insulating material 62 may be changed stepwise according to the ease of heat dissipation. For example, in the first region Z1 where heat is most easily dissipated, a heat insulating coating film 6 containing the heat insulating material 62 to the maximum extent (for example, at a concentration of 50% by volume) with respect to the rust preventive material 61 is formed. In the second region Z2 where heat is least easily dissipated, a rust preventive coating film 60 not containing the heat insulating material 62 is formed. In the third region Z3 where heat is more easily dissipated than the second region and less easily dissipated than the first region Z1, a rust preventive coating film 60 containing the heat insulating material 62 at a predetermined level less than the maximum extent (for example, at a concentration of 10 to 25% by volume) with respect to the rust preventive material 61 may be formed. By configuring in this way, a suitable coating film can be formed according to the necessity of heat insulation.

[0121] 〔Modified Example 2 of Heat Insulating Coating Film〕 The heat insulating coating film 6 in FIG. 5 is formed in one layer or a plurality of layers by applying a paint containing the rust preventive material 61, the heat insulating material 62, and a solvent such as thinner once or a plurality of times. However, the lowermost layer (that is, the layer applied first) may be formed by applying a paint containing the rust preventive material 61 and the solvent once or a plurality of times without containing the heat insulating material 62.

[0122] That is, the heat insulating coating film 6 in FIG. 5 may be a multi-layer coating film in which the lowermost layer is a rust preventive coating film 60 not containing the heat insulating material 62 and the upper layer is a coating film containing the heat insulating material 62. In this case, since the lowermost layer does not contain the heat insulating material 62, it is possible to perform heat preservation of the formwork concrete C1 by the upper layer heat insulating material 62 while exhibiting a rust preventive effect equivalent to that of a conventional rust preventive coating film.

[0123] Note that the heat insulating coating film 6 in FIG. 13 may similarly have a multi-layer structure. In this case, the rust preventive coating film 60 is formed on the entire inner surface of the pit of the formwork 301, and for the first region Z1 where heat is easily dissipated, the heat insulating coating film 6 may be formed on the upper layer of the rust preventive coating film 60.

[0124] 〔Supplementary Note〕 In addition, at least a part of the above-described embodiments and various modifications may be arbitrarily combined with each other. Further, the embodiments and modifications disclosed this time should be considered to be illustrative in all respects and not restrictive. The scope of the present disclosure is indicated by the claims, and it is intended that all modifications within the meaning and scope equivalent to the claims be included.

Explanation of Signs

[0125] 1 Slide center 10 Curing device 2 Gantry carriage 2a Base part 2b Support column 2c Wheel 3 Formwork 3a Top end part 3b Side part 3c Lower end part 300 Formwork 301 Formwork 31 Outer frame 31a Exposed surface 31b Covered surface 32 Web 32a Through hole 33 Reinforcing member 33a First wall part 33b Second wall part 33c Third wall part 34 Reinforcing member 35 Reinforcing member 36 Reinforcing member 37 Reinforcing member 37a First member 37b Second member 38 Reinforcing member 41 Jack 42 Jack 43 Jack 5 Heating member 51 Heating element 52 Electric wire 6 Heat insulation coating 60 Rust preventive coating 61 Rust preventive material 62 Heat insulation material 71 Weld part 71a Weld part 71b Weld part 72 Weld part 73 Weld part 81a Weld part 81b Weld part 81c Weld part 82 Weld part 83 Weld part T1 Tunnel C1 Lining concrete R1 Rail t1 Inner peripheral surface D1 Placing space S1 Enclosed space S2 Enclosed space Y1 Steel material X1 Coating film X2 Coating film X3 Coating film X4 Coating film X5 Coating film H1 Heat source P1 Sensor P2 Sensor P3 Sensor Tp1 Measured temperature (of sensor P1) Tp3 Measured temperature (of sensor P3) Z1 First region Z2 Second region Z3 Third region L1 Shortest distance L L2 Shortest distance L AR1 Arrow AR2 Arrow A1 First peeling mark A2 Second peeling mark A3 Third peeling mark

Claims

1. A metal formwork that forms a placement space for shotcrete between the inner peripheral surface of a tunnel, comprising: an outer frame facing the inner peripheral surface of the tunnel; webs extending from both ends of the outer frame in the tunnel extension direction toward the inside of the pit; reinforcing members arranged at intervals in the circumferential direction on the inside of the pit of the outer frame, extending in the tunnel extension direction, and connected to the web on one end side and the web on the other end side; a plurality of heating members intermittently installed on the exposed surface on the inside of the pit of the outer frame, arranged in a plurality in the circumferential direction with the reinforcing members sandwiched therebetween, for heating the shotcrete through the outer frame; a heat-insulating coating film formed in a first region of the exposed surface where the heating members are not installed, containing a heat-insulating material as an additive; a rust-preventive coating film formed in a second region of the exposed surface where the heating members are installed, containing a rust-preventive material as a base and not containing a heat-insulating material as an additive or having a lower content rate of the heat-insulating material than the heat-insulating coating film; A metal formwork comprising the above.

2. The heat-insulating coating film contains a rust-preventive material as a base and a heat-insulating material as an additive, The heat-insulating material contains wood chips or fly ash, The metal formwork according to Claim 1.

3. The heat-insulating coating film contains fly ash at a concentration of 40% by volume or more and 50% by volume or less with respect to the rust-preventive material, The metal formwork according to Claim 2.

4. The reinforcing member has a plurality of welded portions welded to the outer frame or the web, No welded portion is formed at a portion of the reinforcing member that contacts both the outer frame and the web, The metal formwork according to any one of Claims 1 to 3.

5. The first circumferential end of the reinforcing member facing the first region has a plurality of first welded portions welded to the outer frame, The second circumferential end of the reinforcing member facing the second region has a plurality of second welded portions welded to the outer frame, The shortest distance between the plurality of first welded portions and the web is longer than the shortest distance between the plurality of second welded portions and the web, The metal formwork according to any one of Claims 1 to 4.

6. The plurality of second welded portions are formed at positions that do not overlap with the plurality of first welded portions in the circumferential direction, The metal formwork according to Claim 5.

7. The total length of the plurality of first welded portions in the tunnel extension direction is shorter than the total length of the plurality of second welded portions in the tunnel extension direction, The metal formwork according to Claim 5 or Claim 6.

8. A metal formwork that forms a placement space for covering concrete between the inner peripheral surface of a tunnel, an outer frame facing the inner peripheral surface of the tunnel, webs extending inward from both ends of the outer frame in the tunnel extension direction, reinforcing members that are arranged at intervals in the circumferential direction inside the tunnel of the outer frame, extend in the tunnel extension direction, and are connected to the web on one end side and the web on the other end side, comprising: the reinforcing member has a plurality of welded parts welded to the outer frame or the web, a metal formwork in which the welded parts are not formed at the portion of the reinforcing member that contacts both the outer frame and the web. **Claim 9** The length of the metal formwork in the tunnel extension direction according to any one of Claims 1 to 8 is 2.1 m, A mobile centering with a total extension of 10.5 m, which is configured by connecting five of the metal formworks in the tunnel extension direction.

Images