Tunnel support structures and support structure connection methods

Abstract

To provide technology related to a tunnel shoring that is improved compared to conventional technology.SOLUTION: A tunnel shoring comprises a first steel shoring and a second steel shoring, top ends of which are interconnected while being held by a pair of hands in an erector device. The first steel shoring has a first top end joint plate provided at the top end and a female connecting portion recessed in a single location of the first top end joint plate. The second steel shoring has a second top end joint plate provided at the top end, and a male connecting portion recessed in the single location and locked by being inserted into the female connecting portion. The female connecting portion is eccentrically arranged at a position near a side edge with respect to the center position in the width direction of the first top end joint plate so as not to interfere with a web of the first steel shoring. The male connecting portion is eccentrically arranged at a position near a side edge with respect to the center position in the width direction of the second top end joint plate so as not to interfere with a web of the second steel shoring.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to tunnel support work and a method for connecting support works.

Background Art

[0002] As a method for constructing a tunnel, the NATM method (New Austrian Tunneling Method) is known. The NATM method is a construction method for constructing a tunnel structure integrated with the ground by appropriately using shotcrete, rock bolts, and steel support works based on the concept of maintaining the stability of the tunnel by effectively utilizing the support capacity and strength of the ground.

[0003] When constructing a tunnel by the NATM method, when installing an arch-shaped steel support work, it is usually performed according to the procedure described below. First, a spraying machine is set near the face, and concrete is sprayed onto the face for the first time. When this is completed, the spraying machine is withdrawn. Next, a work vehicle equipped with an erector for building in the support work is placed near the face, and an arch-shaped steel support work is built into the tunnel wall near the face by the erector. When this is completed, the work vehicle is withdrawn. Next, the spraying machine is placed again on the face, and the concrete is sprayed for the second time so as to embed the built-in tunnel support work, and the spraying machine is withdrawn.

[0004] When erecting steel shoring, the general method involves using a hand attached to the boom tip of heavy machinery such as erector devices or drill jumbos to grasp a pair of arc-shaped shoring sections, and then bolting the joint plates located at the top of the left and right shoring sections together to form an arch. However, in reality, this bolting is done manually. In other words, in the connection structure of shoring sections using bolting, it was necessary to manually connect the joint plates located at the top of the shoring sections, position personnel on scaffolding assembled near the tunnel face or on man cages attached to the booms of heavy machinery, move the personnel to near the top of the tunnel, insert bolts between the joint plates of the shoring sections located near the top, and fasten these bolts with nuts.

[0005] In contrast, in recent years, a steel support structure has been proposed in which a male connector is provided on the joint plate of one steel support structure on the left and right sides, and a female connector is provided on the joint plate of the other steel support structure, and the pair of steel supports can be connected in an arch shape by moving the hand of a heavy machine (erector device) that grips the steel supports relative to engage the male connector with the female connector (see, for example, Patent Document 1). With this method of connecting a pair of steel supports by operating the hand of the erector device, it is not necessary to perform connection work such as positioning personnel on a work scaffold assembled near the tunnel wall or on the man cage of the erector device and moving the personnel to the vicinity of the top of the tunnel to bolt the joint plates of the steel supports together, as was done in the past, thus improving work efficiency while ensuring safety.

[0006] Furthermore, Patent Document 1 discloses a steel support structure that employs a single-pronged connection structure in which a female connector is uniformly positioned on the joint plate of one steel support structure and a male connector is uniformly positioned on the joint plate of the other steel support structure. According to this technology, by simply aligning the central axis of the male connector side with the central axis of the male locking member side, a pair of divided support structures can be connected even if the pair of steel support structures are in a relatively twisted state. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2019-163663 [Overview of the project] [Problems that the invention aims to solve]

[0008] However, in the steel support structure described in Patent Document 1, the female and male connectors are positioned in the center of the joint plate in the steel support structure. Therefore, the web of the steel support structure on which the female connector is provided needs to have a notch to suppress interference with the female connector. As a result, the strength of the steel support structure may decrease, or reinforcement may be required to suppress this decrease in strength, indicating that there was room for improvement in the conventional single-bar connection structure of steel supports.

[0009] This invention has been made in view of the above-mentioned problems, and its purpose is to provide an improved tunnel support technology compared to conventional methods. [Means for solving the problem]

[0010] The present invention employs the following means to solve the above problems. That is, the present invention is a tunnel support structure applied to the NATM method and includes first and second arc-shaped divided steel support structures that are erected along the tunnel wall formed by tunnel excavation, the top ends of which are interconnected while being held by a pair of hands in an erector device, the first steel support structure having a first top joint plate provided at the top end and a female type connecting part recessed at a single location on the first top joint plate, and the second steel support structure having a top end provided The joint comprises a second top joint plate and a male connector that is recessed in a single location on the second top joint plate and locked in place by being inserted into the female connector. The female connector is eccentrically positioned closer to the side edge with respect to the widthwise center of the first top joint plate so as not to interfere with the web of the first steel support structure, and the male connector is eccentrically positioned closer to the side edge with respect to the widthwise center of the second top joint plate so as not to interfere with the web of the second steel support structure.

[0011] Here, the female connector may be eccentrically positioned closer to the side edge on the tunnel entrance side with respect to the widthwise center of the first top joint plate, and the male connector may be eccentrically positioned closer to the side edge on the tunnel entrance side with respect to the widthwise center of the second top joint plate.

[0012] Furthermore, a wire mesh is fixed along the ground-side flange of the first top joint plate and the second top joint plate so as to protrude laterally from the face-side edge and the tunnel entrance-side edge of the ground-side flange, and a guide member is provided on the face-side edge of either the first top joint plate or the second top joint plate to assist the insertion operation of the male connector into the female connector by guiding the face-side edge of the other of the first top joint plate or the second top joint plate when connecting the support structure, and the guide member may be provided only on the face-side edge of either the first top joint plate or the second top joint plate.

[0013] Furthermore, the present invention can be specified as any of the tunnel support connection methods described above. That is, the support connection method according to the present invention involves gripping the first and second steel supports with a pair of hands in an erector device, operating the pair of hands, and inserting the male connecting part into the female connecting part to connect the first and second steel supports to each other. [Effects of the Invention]

[0014] According to the present invention, it is possible to provide a technology related to tunnel support that is improved compared to conventional methods. [Brief explanation of the drawing]

[0015] [Figure 1] Figure 1 is a side view of the tunnel support structure according to Embodiment 1. [Figure 2] Figure 2 is a diagram illustrating the tunnel support structure according to Embodiment 1. [Figure 3] Figure 3 is a top view of the work vehicle according to Embodiment 1. [Figure 4] Figure 4 is a side view of the work vehicle according to Embodiment 1. [Figure 5] Figure 5 is a front view of the first top joint plate according to Embodiment 1. [Figure 6] Figure 6 is a rear view of the first top joint plate according to Embodiment 1. [Figure 7] Figure 7 is a front view of the second top joint plate according to Embodiment 1. [Figure 8] Figure 8 is a rear view of the second top joint plate according to Embodiment 1. [Figure 9] Figure 9 is a schematic diagram showing the connecting structure of the left-side steel support structure and the right-side steel support structure according to Embodiment 1. [Figure 10] Figure 10 shows the state in which the female connector and the male connector according to Embodiment 1 are connected. [Figure 11] Figure 11 is a side view of the vicinity of the top end of the left-side steel support structure and the right-side steel support structure according to Embodiment 2. [Figure 12]FIG. 12 is a diagram for explaining a wire mesh fixed to the left steel support and the right steel support according to Embodiment 2. [Figure 13] FIG. 13 is a view of the guide member as seen from the direction of arrow A in FIG. 11. [Figure 14] FIG. 14 is a diagram for explaining a modification example of the guide member according to Embodiment 2. [Figure 15] FIG. 15 is a diagram for explaining a modification example of the guide member according to Embodiment 2.

MODE FOR CARRYING OUT THE INVENTION

[0016] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0017] <Embodiment 1> FIG. 1 is a side view of a tunnel support 10 according to Embodiment 1. The tunnel support 10 is applied to, for example, the NATM method (New Austrian Tunneling Method), and is an arch-shaped steel support built along the wall of the tunnel immediately after excavation to prevent the collapse of the ground exposed due to tunnel excavation, and is installed at regular intervals along the tunnel axis direction. The tunnel support 10 in the present embodiment is composed of a pair of arc-shaped steel supports 10L and 10R. The pair of steel supports 10L and 10R are formed of H-shaped steel having an H-shaped cross section. Each of the steel supports 10L and 10R is formed into an arch-shaped tunnel support 10 as a result of the top ends being interconnected while being respectively gripped by a pair of hands in the erector device. Hereinafter, the steel support 10L will be referred to as the "left steel support", and the steel support 10R will be referred to as the "right steel support". In the present embodiment, the left steel support 10L corresponds to the first steel support, and the right steel support 10R corresponds to the second steel support.

[0018] ​​The left-side steel support structure 10L has a first main body 111, a first top joint plate 121, and a first bottom plate 131. The first main body 111 is an H-shaped steel structure composed of a web 111a, a pair of ground-side flanges 111b and internal-side flanges 111c perpendicular to the web 111a. The first top joint plate 121 is welded to one end of the first main body 111, and the first bottom plate 131 is welded to the other end. The first top joint plate 121 and the first bottom plate 131 are rectangular steel plates that extend perpendicular to the H-shaped cross-section of the first main body 111. The ground-side flange 111b is the flange that faces the ground when the support structures are connected (when the left-side steel support structure 10L and the right-side steel support structure 10R are connected). On the other hand, the inner flange 111c is the flange that faces the tunnel interior when the support structure is connected.

[0019] Similarly, the right-side steel support structure 10R also has a second main body 112, a second top joint plate 122, and a second bottom plate 132. The second main body 112 is H-shaped and consists of a web 112a, a pair of ground-side flanges 112b and internal-side flanges 112c perpendicular to the web 112a. It is made of steel. A second top joint plate 122 is welded to one end of the second main body 112, and a second bottom plate 132 is welded to the other end. The second top joint plate 122 and the second bottom plate 132 are rectangular steel plates that extend perpendicular to the H-shaped cross-section of the second main body 112. The ground-side flange 112b is the flange that faces the ground when the support structure is connected. On the other hand, the internal-side flange 112c is the flange that faces the tunnel interior when the support structure is connected.

[0020] In this embodiment, the first top joint plate 121 and the second top joint plate 122 have a contiguous square plane. As shown in Figure 1, the left steel support structure 10L and the right steel support structure 10R are connected with the first top joint plate 121 and the second top joint plate 122 butted against each other.

[0021] Figure 2 is a diagram illustrating the tunnel support structure 1 according to Embodiment 1. In Figure 2, reference numeral 3 denotes the primary shotcrete layer. Reference numeral 6 denotes the secondary shotcrete layer. Figure 2 also shows the right-side steel support structure 10R of the tunnel support structure 10. In the tunnel construction method of this embodiment, after the excavation of the face 8 exposes the ground 7 on the side of the tunnel T, a primary shotcrete layer 3 is formed by spraying primary concrete onto this ground 7. Subsequently, the arch-shaped tunnel support structure 10 described above is erected on the inner side of the primary shotcrete layer 3 along the tunnel wall. The tunnel support structures 10 are arranged adjacent to the face 8 side and in the axial direction of the tunnel T, at predetermined intervals (for example, about 1.0m to 1.5m) relative to the existing tunnel support structures 10 located on the portal side of the tunnel T. The erection of the tunnel support structures 10 is performed using an erector device equipped with a hand attached to the tip of a pair of booms.

[0022] Figure 3 is a top view of the work vehicle 200 according to Embodiment 1. Figure 4 is a side view of the work vehicle 200 according to Embodiment 1. The work vehicle 200 is a self-propelled heavy machine equipped with an erector device 100 and a spraying device 600 for erecting tunnel support structures 10. The erector device 100 is equipped with a pair of booms 17L and 17R of the same configuration. The pair of booms 17L and 17R can be freely extended and retracted, tilted, swung, and rotated by the operation of the drive mechanism attached to them. In addition, a pair of hands 18L and 18R of the same configuration are connected to the tips of each boom 17L and 17R. The pair of hands 18L and 18R can be freely rotated and swung by the operation of the drive mechanism attached to them, and can detachably clamp and grip (hold) the left steel support structure 10L and the right steel support structure 10R, respectively. The erector device 100 grips the left-side steel support 10L and the right-side steel support 10R with a pair of hands 18L and 18R, and by driving each hand 18L and 18R, it can connect the left-side steel support 10L and the right-side steel support 10R and erect them in a predetermined installation position.

[0023] Hereinafter, the boom indicated by reference numeral 17L will be referred to as the "left boom," and the boom indicated by reference numeral 17R will be referred to as the "right boom." Similarly, the hand indicated by reference numeral 18L will be referred to as the "left hand," and the hand indicated by reference numeral 18R will be referred to as the "right hand." The erector device 100 can detachably grip the left steel support 10L with the left hand 18L, and detachably grip the right steel support 10R with the right hand 18R. In this embodiment, the left steel support 10L and the right steel support 10R are a pair of support members formed by dividing the arch-shaped tunnel support 10 into two parts. After being guided near the tunnel face 8, these are assembled at the tunnel face 8 to form the arch-shaped tunnel support 10.

[0024] The spraying device 600 is positioned between the left boom 17L and the right boom 17R, and includes an arm 601, a spraying robot 602 supported by the arm 601, and a spraying nozzle 603 provided at the tip of the spraying robot 602. The arm 601 is retractable. The spraying robot 602 is capable of tilting and rotating the spraying nozzle 603. In addition, the spraying device 600 is equipped with a concrete pump, a quick-setting agent supply device, a compressor, a high-pressure water pump, etc. The spraying robot 602 can spray the sprayed concrete onto the tunnel face 8 by discharging the sprayed concrete supplied from the concrete pump through the spraying nozzle 603.

[0025] The construction of tunnel T is carried out by repeating the following cycle, for example: (1) excavating the tunnel face 8 by blasting or machinery → (2) removing spoil → (3) spraying primary shotcrete → (4) erecting tunnel supports → (5) spraying secondary shotcrete → (6) installing rock bolts. This is repeated as one cycle to extend tunnel T in the axial direction. (2) After the spoil removal process is completed, a work vehicle 200 equipped with an erector device 100 is positioned near the tunnel face 8. At this time, the work vehicle 200 is driven by itself and positioned near the tunnel face 8 with the left-side steel supports 10L and the right-side steel supports 10R, respectively, gripped by the hands 18L and 18R of the erector device 100 along the tunnel axis (tunnel extension direction). Then, (3) in the primary spraying of the primary sprayed concrete, the primary sprayed concrete layer 3 is formed by spraying the primary sprayed concrete onto the ground 7 (tunnel wall) where the left-side steel support 10L and the right-side steel support 10R will be erected, using the spraying device 600. Next, (4) in the erection of the tunnel support, the left-side steel support 10L and the right-side steel support 10R are gripped by the respective hands 18L and 18R and the respective hands 18L and 18R are driven to connect the top ends of the left-side steel support 10L and the right-side steel support 10R to each other, and the arch-shaped tunnel support 10 is erected in the correct erection position.

[0026] The following describes the connection structure of the tunnel support structure 10 (left-side steel support structure 10L and right-side steel support structure 10R).

[0027] Figure 5 is a front view of the first top joint plate 121 according to Embodiment 1. Figure 6 is a rear view of the first top joint plate 121 according to Embodiment 1. Here, reference numeral 121a denotes the outer surface of the first top joint plate 121, and reference numeral 121b denotes the inner surface of the first top joint plate 121. Reference numeral 121c denotes the upper edge of the first top joint plate 121, reference numeral 121d denotes the lower edge of the first top joint plate 121, reference numeral 121e denotes the tunnel entrance side edge of the first top joint plate 121, and reference numeral 121f denotes the tunnel face side edge of the first top joint plate 121. Here, the lower edge 121d of the first top joint plate 121 faces the interior side of the tunnel T when the left steel support structure 10L and the right steel support structure 10R are connected, and the upper edge 121c faces the opposite side, i.e., the ground side 7. Furthermore, the face-side edge 121f of the first top joint plate 121 is positioned facing the face 8 side of the tunnel T when the left-side steel support structure 10L and the right-side steel support structure 10R are connected, while the portal-side edge 121e is positioned on the opposite side, i.e., facing the portal side (the side of the erector device 100).

[0028] In Figure 6, the end shape (H-shape) of the first main body portion 111 connected to the first top joint plate 121 is shown by a dashed line. Figures 5 and 6 also illustrate the vertical direction (height direction) and width direction of the first top joint plate 121. The vertical direction of the first top joint plate 121 is parallel to the extension direction of the shaft entrance side edge 121e and the face side edge 121f, and is also parallel to the extension direction of the web 111a at the position where the first main body portion 111 connects with the first top joint plate 121. The width direction of the first top joint plate 121 is parallel to the extension direction of the upper edge 121c and the lower edge 121d, and is also parallel to the extension direction of the ground side flange 111b and the internal side flange 111c at the position where the first main body portion 111 connects with the first top joint plate 121. In Figure 5, the symbol X1 represents the center line in the width direction of the first top joint plate 121. The symbol Y1 represents the center line in the height direction of the first top joint plate 121.

[0029] Figure 7 is a front view of the second top joint plate 122 according to Embodiment 1. Figure 8 is a rear view of the second top joint plate 122 according to Embodiment 1. Here, reference numeral 122a denotes the second top joint plate. The outer surface of 122, reference numeral 122b, is the inner surface of the second crest joint plate 122. Reference numeral 122c is the upper edge of the second crest joint plate 122, reference numeral 122d is the lower edge of the second crest joint plate 122, reference numeral 122e is the portal side edge of the second crest joint plate 122, and reference numeral 122f is the face side edge of the second crest joint plate 122. Here, the lower edge 122d of the second crest joint plate 122 faces the interior side of the tunnel T when the left steel support structure 10L and the right steel support structure 10R are connected, and the upper edge 122c faces the opposite side, i.e., the ground side 7. Furthermore, the face-side edge 122f of the second top joint plate 122 is positioned facing the tunnel face 8 side when the left-side steel support structure 10L and the right-side steel support structure 10R are connected, while the portal-side edge 122e is positioned on the opposite side, i.e., facing the portal side (the side of the erector device 100).

[0030] In Figure 8, the end shape of the second main body portion 112 connected to the second top joint plate 122 is shown by a dashed line. Figures 7 and 8 also illustrate the vertical and width directions of the second top joint plate 122. In Figure 7, the reference numeral X2 represents the center line of the second top joint plate 122 in the width direction. The reference numeral Y2 represents the center line of the second top joint plate 122 in the height direction.

[0031] The first top joint plate 121 and the second top joint plate 122 shown in Figures 5 to 8 have a substantially square planar shape. The vertical dimensions of the first top joint plate 121 and the second top joint plate 122 are equal to each other, and the horizontal dimensions of the first top joint plate 121 and the second top joint plate 122 are also equal to each other. In other words, the first top joint plate 121 and the second top joint plate 122 have a congruent square planar shape, and the dimensions of the upper edges 121c, 122c, lower edges 121d, 122d, portal side edges 121e, 122e, and face side edges 121f, 122f are equal to each other. However, the first top joint plate 121 and the second top joint plate 122 may have a rectangular planar shape.

[0032] As shown in Figures 5 and 6, a single female connector 40 is recessed in the first top joint plate 121. The female connector 40 is eccentrically positioned closer to the side edge with respect to the widthwise center of the first top joint plate 121 so as not to interfere with the web 111a of the left-side steel support 10L. More specifically, the female connector 40 is eccentrically positioned closer to the portal side edge 121e with respect to the widthwise center of the first top joint plate 121. The female connector 40 is also positioned at the vertical center of the first top joint plate 121. The symbol C1 in Figure 5 is the center of the female connector 40. The symbol E1 in Figure 5 is the amount of eccentricity from the center line X1 in the widthwise direction of the first top joint plate 121 to the center C1 of the female connector 40.

[0033] Furthermore, a single male connector 50 is provided protruding from the second top joint plate 122. The male connector 50 is eccentrically positioned closer to the side edge with respect to the center in the width direction of the second top joint plate 122 so as not to interfere with the web 112a of the right-side steel support 10R. More specifically, the male connector 50 is eccentrically positioned closer to the side edge 122e on the tunnel entrance side with respect to the center in the width direction of the second top joint plate 122. The male connector 50 is also positioned at the center in the height direction of the second top joint plate 122. The symbol C2 in Figure 7 is the center of the male connector 50. The symbol E2 in Figure 7 is the amount of eccentricity from the center line X2 in the width direction of the second top joint plate 122 to the center C2 of the male connector 50. In this embodiment, the eccentricity E2 of the male connector 50 in the width direction is set to be equal to the eccentricity E1 of the female connector 40 in the width direction.

[0034] Figure 9 is a schematic diagram showing a connecting structure 30 that connects the left steel support structure 10L and the right steel support structure 10R according to Embodiment 1. The connecting structure 30 is composed of a single female connecting part 40 provided on the first top joint plate 121 and a single male connecting part 50 provided on the second top joint plate 122. Figure 9 shows the state before the left steel support structure 10L and the right steel support structure 10R are connected via the connecting structure 30, that is, the outer surface 121a of the first top joint plate 121 and the outer surface 122a of the second top joint plate 122 are facing each other and spaced apart. In Figure 9, for convenience, the first main body portion 111 connected to the first top joint plate 121 and the second main body portion 112 connected to the second top joint plate 122 are omitted from the illustration.

[0035] First, the male connecting portion 50, which is protruding from the second top joint plate 122, will be described. An opening hole 1222, which is a through hole, is drilled in the second top joint plate 122 at the position where the male connecting portion 50 is provided. The male connecting portion 50 also has a rod-shaped male locking member 51. The male locking member 51 is a shaft member with a diameter slightly smaller than the opening hole 1222 of the second top joint plate 122, and a male screw 51a is engraved on its base end. In addition, a male screw 51c is formed on the outer circumference of the male locking member 51 over a predetermined range. The male screw 51c of the male locking member 51 is a circumferential male locking groove arranged in parallel on the outer circumference of the male locking member 51. In addition, a tapered surface 51e that decreases in diameter towards the tip is formed on the tip portion 51d of the male locking member 51.

[0036] Here, a nut 52 is fixed to the inner surface 122b of the second top joint plate 122 by welding or the like at the location where the opening hole 1222 is drilled in the second top joint plate 122. The male locking member 51 can be attached to the second top joint plate 122 in a state protruding from the outer surface 122a, as shown in Figure 9, by inserting its base end through the opening hole 1222 from the outer surface 122a side of the second top joint plate 122 and screwing the male screw 51a onto the nut 52. As a result, the male connecting part 50 is provided protruding from the second top joint plate 122. Note that, as shown in Figures 7 and 8, the male connecting part 50 is eccentrically positioned laterally with respect to the widthwise center of the second top joint plate 122, so that the nut 52 for screwing the male locking member 51 and the web 112a do not interfere with each other.

[0037] Next, the female mold connecting portion 40 recessed in the first top joint plate 121 will be described. An opening hole 1212, which is a through hole, is drilled in the first top joint plate 121 at the position where the female mold connecting portion 40 is provided. Furthermore, a cylindrical metal casing 41 is fixed to the inner surface 121b of the first top joint plate 121 by welding wp or the like at the position where the opening hole 1212 is drilled in the first top joint plate 121. Note that the female mold connecting portion 40 is eccentrically positioned laterally with respect to the center position in the width direction of the first top joint plate 121, so that interference between the casing 41 and the web 111a is suppressed. Also, as shown in Figure 9, a tapered surface 1215 is formed on the edge of the opening hole 1212 formed in the first top joint plate 121, which gradually widens in diameter from the inner surface 121b side to the outer surface 121a side in the thickness direction of the first top joint plate 121.

[0038] The casing 41 has its axis positioned approximately in the center of the opening hole 1212. A storage chamber 42 is formed inside the casing 41. At the front of the storage chamber 42, a tapered hole 43 is formed, having a tapered surface 43a on its inner circumferential surface where the inner diameter gradually decreases from the rear end to the front end. A spring storage section 42a is formed in the middle of the storage chamber 42, and a female screw 45 is engraved on the inner circumference of the rear part of the storage chamber 42. An insertion opening 48 is formed at the tip of the tapered hole 43. The insertion opening 48, located at the front end of the casing 41, has approximately the same diameter as the opening hole 1212 formed in the first top joint plate 121 and communicates with the opening hole 1212. Furthermore, when the casing 41 is fixed to the first top joint plate 121, the insertion opening 48 is positioned to overlap with the opening hole 1212.

[0039] Furthermore, a wedge-shaped female locking member 46, divided into three sections in the circumferential direction, is slidably arranged within the tapered hole 43. The outer surface of the female locking member 46 is formed as a tapered surface 46a that can slide along the tapered surface 43a in the tapered hole 43. The outer diameter of the tapered surface 46a of the female locking member 46 gradually increases from the tip to the rear. In addition, female threads 46b are formed on the inner surface of each female locking member 46. The female threads 46b are multiple circumferential female locking grooves arranged side by side on the inner surface of each female locking member 46. The female threads 46b are engraved in an arc centered on the axis of the casing 41 and in a direction along the axis. Multiple female locking members 46 form a female screw hole, and as the tapered surface 46a of each female locking member 46 retracts along the tapered surface 43a of the tapered hole 43, the female screw hole expands in diameter, and as it moves forward (towards the front), the female screw hole shrinks in diameter. Furthermore, the female threads 46b formed on the inner surface of each female locking member 46 can engage with the male threads 51c formed on the outer circumference of the tip side of the male locking member 51.

[0040] Furthermore, in the spring storage section 42a of the storage chamber 42, a compression spring 44, which is a pressing member that presses the female locking member 46 forward (elastically biases) is stored in a compressed state between a spring receiver 47 provided at the rear end of each female locking member 46 and a cover plate 49, and the pressing force of the compression spring 44 constantly presses each female locking member 46 forward. The cover plate 49 can be screwed into a female screw 45 engraved on the inner circumference of the rear part of the storage chamber 42, thereby holding the compression spring 44 in a compressed state. A hexagonal hole 49a is provided on the outer surface of the cover plate 49, and the cover plate 49 can be attached to and detached from the casing 41 using a hexagonal wrench.

[0041] Next, the procedure for connecting the left-side steel support 10L and the right-side steel support 10R will be described. When connecting the left-side steel support 10L and the right-side steel support 10R, first, the erector device 100 grips the left-side steel support 10L with the left-side hand 18L and the right-side steel support 10R with the right-side hand 18R. Then, the erector device 100 extends and tilts the left-side boom 17L and the right-side boom 17R as appropriate, and rotates the left-side hand 18L and the right-side hand 18R to move the left-side steel support 10L and the right-side steel support 10R so that they are perpendicular to the tunnel axis.

[0042] Then, as shown in Figure 9, the distance between the first top joint plate 121 and the second top joint plate 122 is gradually reduced from a state in which the first top joint plate 121 of the left steel support structure 10L and the second top joint plate 122 of the right steel support structure 10R are close together and facing each other (opposing). This is done so that the male locking member 51 of the male connecting part 50 is inserted into the opening hole 1212 of the first top joint plate 121.

[0043] Here, the outer diameter of the male locking member 51 is set to be slightly smaller than the opening hole 1212 of the first top joint plate 121 and the insertion opening 48 of the female connecting part 40 (casing 41), and slightly larger than the diameter of the female screw hole formed by each female locking member 46 when each female locking member 46 is positioned at the furthest forward position of the tapered hole 43 (tapered surface 43a). When the male locking member 51, which is protruding from the second top joint plate 122, enters through the opening hole 1212 of the first top joint plate 121 and into the insertion opening 48 of the female connecting part 40, the tip 51d of the male locking member 51 comes into contact with the front end surface 46c of each female locking member 46, which is positioned at the furthest forward position of the tapered hole 43 (tapered surface 43a) at its front end due to the pressing force of the pressing spring 44. Then, the male locking member 51 resists the pressing force of the pressing spring 44, causing each female locking member 46 to retract along the tapered surface 43a toward the axial rear of the female connecting portion 40 (casing 41), thereby expanding the diameter of the female screw holes formed by the female threads 46b on the tapered surface 46a of each female locking member 46, and allowing the male locking member 51 to be inserted into the storage chamber 42.

[0044] Then, the outer surface 121a of the first top joint plate 121 and the outer surface 122a of the second top joint plate 122 come into contact, and when the insertion of the male locking member 51 into the storage chamber 42 of the female joint portion 40 is completed, further insertion of the male locking member 51 into the storage chamber 42 is stopped, and each female locking member 46 is pushed back forward (towards the front) by the pressing force of the pressing spring 44, and the female screw hole formed by the tapered surface 46a of each female locking member 46 shrinks in diameter. As a result, as shown in Figure 10, the female screw 46b (female locking groove) of each female locking member 46 in the female joint portion 40 and the male screw 51c (male locking groove) of the male locking member 51 in the male joint portion 50 engage with each other. As a result, as shown in Figure 10, the outer surface 121a of the first top joint plate 121 and the outer surface 122a of the second top joint plate 122 are in surface contact with each other. The left-side steel support structure 10L and the right-side steel support structure 10R are connected as a single unit.

[0045] Here, as shown in Figure 10, when the female thread 46b of the female connector 40 and the male thread 51c of the male connector 50 (male locking member 51) are engaged, and an external force is applied in a direction that separates the first top joint plate 121 and the second top joint plate 122, a pull-out force is applied in a direction that pulls the male locking member 51 out of the storage chamber 42 in the female connector 40. This pull-out force is transmitted to each female locking member 46 via the male thread 51c and female thread 46b that are engaged with each other. However, the tapered surface 46a of each female locking member 46 gradually decreases in outer diameter from the rear to the front. Therefore, even when the above pull-out force is applied to each female locking member 46, the displacement of each female locking member 46 toward the front of the tapered hole 43 is limited. In other words, according to the connecting structure 30 of this embodiment, even if an external force is applied in the direction of pulling the male locking member 51 out of the storage chamber 42 of the female connecting portion 40, the connected state can be maintained against the external force. In the state in which the male locking member 51 of the male connecting portion 50 is locked to the female connecting portion 40, that is, in the state in which the female threads 46b of each female locking member 46 of the female connecting portion 40 and the male threads 51c of the male locking member 51 are engaged with each other, the pulling out of the male locking member 51 from the casing 41 of the female connecting portion 40 is restricted as described above, but the rotation of the male locking member 51 with respect to the casing 41 as the center of rotation is permitted.

[0046] According to the steel support structure 30 of this embodiment, the male connecting part 50 (male locking member 51) is connected to the female connecting part 40 with a single touch by simply inserting the male connecting part 50 (male locking member 51) axially from the insertion opening 48 of the female connecting part 40, thereby enabling the left steel support structure 10L and the right steel support structure 10R to be fastened together as a single unit. By adopting such a one-touch connection structure, it is not necessary to perform connection work such as positioning personnel on work scaffolding or man cages of erector devices assembled near the tunnel wall, moving the personnel to the vicinity of the tunnel top, and bolting the joint plates located at the top of the pair of steel support structures, as was done in the past. Therefore, according to the steel support structure 30 of this embodiment, the connection work of the left steel support structure 10L and the right steel support structure 10R can be performed more quickly and easily than in the past. Furthermore, according to the steel support structure 30 in this embodiment, the left steel support structure 10L and the right steel support structure 10R can be connected by operating the hands 18L and 18R attached to the tips of the pair of booms 17L and 17R in the erector device 100. This eliminates the need for manual labor at the tunnel face, thereby further improving safety and work efficiency compared to conventional methods.

[0047] Furthermore, in the steel support structure 30 of this embodiment, a single-pronged connection structure is adopted that connects a female connector 40, which is individually positioned on the first top joint plate 121, and a male connector 50, which is individually positioned on the second top joint plate 122. Therefore, even if the first top joint plate 121 and the second top joint plate 122 are twisted in planar (the outer edges of the first top joint plate 121 and the second top joint plate 122 do not overlap and are misaligned), the left steel support structure 10L and the right steel support structure 10R can be connected even more easily by inserting the male connector 51 into the casing 41 (storage chamber 42), simply by aligning the female connector 40 and the male connector 50 (male locking member 51).

[0048] Furthermore, according to the steel support structure 30 in this embodiment, as described above, even after the left steel support structure 10L and the right steel support structure 10R are connected, rotational movement of the male locking member 51 around the central axis CL2 relative to the casing 41 is permitted. Therefore, after the connection, the positions of the first top joint plate 121 and the second top joint plate 122 can be adjusted so that they are in full surface contact. As a result, when the female connecting portion 40 of the first top joint plate 121 and the male locking member 51 of the second top joint plate 122 are connected, the upper edge 121c, lower edge 121d, portal side edge 121e, and face side edge 121f of the first top joint plate 121 overlap the upper edge 122c, lower edge 122d, portal side edge 122e, and face side edge 122f of the second top joint plate 122, respectively. This makes it easy to align the position.

[0049] Furthermore, in this embodiment, the female connector 40 and the male connector 50 are eccentrically positioned near the side edges of the first and second top joint plates 121 and 122, with reference to the widthwise center position of the first and second top joint plates 122. As a result, the female connector 40 and the male connector 50 do not interfere with the webs 111a and 112a of the left steel support 10L and the right steel support 10R, respectively. Therefore, unlike the connection structure disclosed in Patent Document 1, there is no need to form notches in the webs 111a and 112a of the left steel support 10L and the right steel support 10R. Thus, there is no need for the webs 111a and 112a of the left steel support 10L and the right steel support 10R to become weak points in terms of strength, nor is there any need to reinforce the webs 111a and 112a as a countermeasure.

[0050] In particular, in this embodiment, the female connector 40 is eccentrically positioned from the widthwise center of the first top joint plate 121 towards the portal side edge 121e, and the male connector 50 is eccentrically positioned from the widthwise center of the second top joint plate 122 towards the portal side edge 122e. The portal side edges 121e and 122e of each top joint plate 121 and 122 can be said to be the side edges that face the erector device 100 when the support structure is connected. Therefore, according to the above embodiment, the visibility of the female connector 40 and the male connector 50 is excellent when the support structure is connected. In other words, when the support structure is connected, for example, the operator of the erector device 100 can easily see the female connector 40 and the male connector 50 from the cockpit, and the left steel support structure 10L and the right steel support structure 10R can be connected smoothly and easily. Furthermore, by eccentrically arranging the female connector 40 and the male connector 50 towards the tunnel entrance as described above, there are additional advantages as follows. That is, for example, after erecting the tunnel support structure 10, which is formed in an arch shape by connecting the left-side steel support structure 10L and the right-side steel support structure 10R as described above, when a load from the tunnel face 8 side acts on the tunnel support structure 10 due to the pushing of the tunnel face 8, etc., the load tends to act in a direction that causes the tunnel entrance side edges 121e and 122e to open up at the connection part of the first top joint plate 121 and the second top joint plate 122. In contrast, by adopting a connection structure in which the female connector 40 is eccentrically positioned from the widthwise center of the first top joint plate 121 towards the portal side edge 121e, and the male connector 50 is eccentrically positioned from the widthwise center of the second top joint plate 122 towards the portal side edge 122e, the female connector 40 and the male connector 50 function more favorably as resistance elements against the extrusion force from the tunnel face 8 (for example, compared to the case where the female connector 40 and the male connector 50 are eccentrically positioned towards the tunnel face 8), and the opening of the first top joint plate 121 and the second top joint plate 122 on the portal side edge 121e, 122e can be favorably suppressed. In other words, the connection structure in which the female connector 40 and the male connector 50 are eccentrically positioned towards the tunnel face not only improves constructability as described above, but also provides excellent resistance to extrusion from the tunnel face 8.

[0051] In the example shown in Figures 5-6, the eccentricity E1 of the female connector 40 is approximately 1 / 4 of the width dimension of the first top joint plate 121. That is, in the width direction of the first top joint plate 121, the female connector 40 is positioned approximately in the center between the center position and the side edge 121e on the tunnel entrance side. However, the position of the female connector 40 in the width direction of the first top joint plate 121 is not limited to the above configuration, and the eccentricity E1 of the female connector 40 can be freely set. Also, in the example shown in Figures 5-6, the female connector 40 is positioned approximately in the center in the vertical direction of the first top joint plate 121, but this is not the only option. The female connector 40 may be eccentrically positioned on the upper edge 121c side or the lower edge 121d side in the height direction of the first top joint plate 121. Similarly, in one example shown in Figures 7-8, the eccentricity E2 of the male connector 50 is approximately 1 / 4 of the width dimension of the second top joint plate 122. That is, in the width direction of the second top joint plate 122, the male connector 50 is positioned approximately in the center between the central position and the tunnel entrance side edge 122e. However, the position of the male connector 50 in the width direction of the second top joint plate 122 is not limited to the above configuration, and the eccentricity E2 of the male connector 50 can be freely set. Also, in one example shown in Figures 7-8, the male connector 50 is positioned approximately in the center in the vertical direction of the second top joint plate 122. However, it is not limited to this. The male connector 50 may be eccentrically positioned on the upper edge 122c side or the lower edge 122d side in the height direction of the second top joint plate 122.

[0052] However, if the female connector 40 and the male connector 50 are eccentrically positioned near the side edges of each top joint plate 121 and 122, with reference to the widthwise center position of the first top joint plate 121 and the second top joint plate 122, interference with the webs 111a and 112a can be avoided, and to that extent, the position of the female connector 40 and the male connector 50 on each top joint plate 121 and 122 is not particularly limited.

[0053] In other words, for example, the female connector 40 may be eccentrically positioned closer to the face-side edge 121f with respect to the widthwise center position of the first top joint plate 121, and the male connector 50 may be eccentrically positioned closer to the face-side edge 121f with respect to the widthwise center position of the second top joint plate 122, thereby avoiding interference between the female connector 40 and the male connector 50 and the webs 111a and 112a.

[0054] Furthermore, when connecting the left-side steel support structure 10L and the right-side steel support structure 10R to erect the arch-shaped tunnel support structure 10 at a predetermined installation location, the prisms attached to the left-side steel support structure 10L and the right-side steel support structure 10R may be automatically tracked by a surveying instrument such as a total station, and the hands 18L and 18R of the erector device 100 may be operated while acquiring their three-dimensional coordinates. Since such technology is publicly known, a detailed explanation will be omitted, but for example, the tunnel support structure installation system disclosed in Patent Document 1 can be applied. In addition, the installation procedure for the tunnel support structure 10 and the spraying procedure for the secondary shotcrete can also be applied, for example, the construction procedure disclosed in Patent Document 1.

[0055] <Embodiment 2> Next, Embodiment 2 of the present invention will be described. Figure 11 is a side view of the vicinity of the top end of the left steel support structure 10L and the right steel support structure 10R according to Embodiment 2. Figure 12 is a diagram illustrating the wire mesh 15 fixed along the ground-side flange 111b of the left steel support structure 10L and the ground-side flange 112b of the right steel support structure 10R according to Embodiment 2. This embodiment is the same as Embodiment 1, except that a guide member 14 is provided on the first top joint plate 121 of the left steel support structure 10L, and the wire mesh 15 is fixed to the ground-side flanges 111b and 112b of the left steel support structure 10L and the right steel support structure 10R. That is, in this embodiment, the configuration of the female connector 40 on the first top joint plate 121 and the configuration of the male connector 50 on the second top joint plate 122 are the same as in Embodiment 1. In Figure 11, the female connector 40 and the male connector 50 are schematically shown. In the following, the same reference numerals are used for components identical to those in Embodiment 1, and detailed explanations are omitted. The explanation will focus on the differences from Embodiment 1.

[0056] In this embodiment, a guide member 14 is provided on the face-side edge 121f of the first top joint plate 121. The guide member 14 is a member that assists the insertion operation of the male connector 50 into the female connector 40 by guiding the face-side edge 122f of the second top joint plate 122 when connecting the shoring. Figure 13 is a view of the guide member 14 from the direction of arrow A in Figure 11. The guide member 14 is made of, for example, a metal plate. In the examples shown in Figures 11 and 13, the guide member 14 is made by bending the metal plate in the middle, and includes a straight portion 141 formed on the base end side and an inclined portion 142 formed on the tip end side. The straight portion 141 of the guide member 14 is joined to the face-side edge 121f of the first top joint plate 121 by welding or the like so that it stands perpendicular to the outer surface 121a of the first top joint plate 121. The inclined portion 142 of the guide member 14 is connected at an inclination to the straight portion 141. That is, the guide member 14 is connected to the straight portion 141. The inner surface position of 41 corresponds to the position of the face-side edge 121f of the first top joint plate 121, and is inclined toward the outside of the first top joint plate 121 (i.e., toward the face 8 side of the tunnel T when the support structure is connected) with respect to the inclined portion 142. Note that the wire mesh 15 is not shown in Figure 13.

[0057] Furthermore, as shown in Figure 11, the width dimension of the guide member 14 is smaller than the side length of the face-side edge 121f of the first top joint plate 121, and in the illustrated example, the guide member 14 is erected near the center of the face-side edge 121f. Therefore, as shown in Figure 11, a step is formed between the upper end of the guide member 14 and the upper edge 121c of the first top joint plate 121. In addition, the projection dimension of the straight portion 141 relative to the outer surface 121a of the first top joint plate 121 is set to be greater than or equal to the projection length of the male locking member 51 protruding from the outer surface 122a of the second top joint plate 122.

[0058] Next, with reference to Figures 11 and 12, the wire mesh 15 of the left-side steel support structure 10L and the right-side steel support structure 10R will be described. The wire mesh 15 is a member for suppressing cracking of the secondary shotcrete layer 6, and is covered by the secondary concrete when the secondary concrete is shotcrete onto the tunnel cavity. The wire mesh 15 is fixed in advance by welding or the like to the upper surfaces of the ground-side flange 111b of the left-side steel support structure 10L and the ground-side flange 112b of the right-side steel support structure 10R. As an example, the wire mesh 15 has a grid shape, and one mesh (one square) of the wire mesh 15 may be, for example, about 150 mm square. For example, the wire mesh 15 is arranged along the entire length in the longitudinal direction of the ground-side flanges 111b and 112b.

[0059] Of the wire mesh 15, the portion indicated by reference numeral 15A is the portion that protrudes laterally from the face-side edges 1113 and 1123 of the ground-side flanges 111b and 112b (hereinafter referred to as the "face-side protrusion"). On the other hand, the portion indicated by reference numeral 15B is the portion that protrudes laterally from the tunnel entrance-side edges 1114 and 1124 of the ground-side flanges 111b and 112b (hereinafter referred to as the "tunnel entrance-side protrusion"). Note that the face-side edges 1113 and 1123 of the ground-side flanges 111b and 112b are the side edges that face the tunnel face 8 when connecting the steel supports 10L and 10R. On the other hand, the tunnel entrance side edges 1114 and 1124 of the ground-side flanges 111b and 112b are side edges located on the opposite side of the tunnel face side edges 1113 and 1123, and face the tunnel entrance side (i.e., the erector device 100 side) when the support structure is connected.

[0060] As shown in Figure 12, the wire mesh 15 has a second projection length, where the tunnel entrance projection 15B protrudes laterally from the tunnel entrance edges 1114 and 1124, which is longer than the first projection length, where the tunnel entrance projection 15A protrudes laterally from the tunnel entrance edges 1113 and 1123. In the example shown in Figure 12, the first projection length of the tunnel entrance projection 15A of the wire mesh 15 corresponds to the size of one mesh, and the second projection length of the tunnel entrance projection 15B corresponds to the size of five meshes. In this configuration, to prevent the tunnel entrance projection 15B of the wire mesh 15, which is fixed to the ground-side flanges 111b and 112b by welding or the like, from bending (sagging) downward due to its own weight, the left-side steel support structure 10L and the right-side steel support structure 10R are provided with support members 16 that support the tunnel entrance projection 15B from below. The support member 16 is not particularly limited as long as it supports the tunnel entrance side projection 15B, but it can be configured to include a support anchor 161 and a spacer 162.

[0061] In the example shown in Figure 12, the support anchor 161 is a rod-shaped anchor member that protrudes vertically from the webs 111a and 112a of the left-side steel support structure 10L and the right-side steel support structure 10R. The support anchor 161 is, for example, welded at its base end to the portal-side web surfaces 1111 and 1121 of the webs 111a and 112a. The portal-side web surfaces 1111 and 1121 are the surfaces facing the portal side, opposite to the tunnel face 8, when erecting the tunnel support structure 10. Also, the reference numeral 163 in Figure 12 indicates the support anchor 161 in order to ensure the perpendicularity of the support anchor 161 to the webs 111a and 112a (portal-side web surfaces 1111 and 1121). This is a fastener for fixing the intermediate portion to the back surface of the ground-side flanges 111b and 112b. This fastener 163 may be, for example, a nut welded to the back surface of the ground-side flanges 111b and 112b, and the intermediate portion of the support anchor 161 is fixed to the back surface of the ground-side flanges 111b and 112b by passing the support anchor 161 through the nut.

[0062] The spacer 162 is a member installed to maintain an appropriate distance between the tunnel-side projection 15B of the wire mesh 15 and the support anchor 161. The spacer 162 may be welded to the support anchor 161 and the tunnel-side projection 15B. Alternatively, the spacer 162 may be fixed to the tunnel-side projection 15B of the wire mesh 15 using binding wire or the like. With the support member 16 as described above, the tunnel-side projection 15B of the wire mesh 15 is prevented from bending due to its own weight and the tunnel-side projection 15B can be held in a position along the ground-side flanges 111b and 112b. As shown in Figure 12, the support anchor 161 is fixed to the upper side of the webs 111a and 112a, that is, to the part closer to the ground-side flanges 111b and 112b. This makes it possible to reduce the distance between the tunnel-side projection 15B of the wire mesh 15 and the support anchor 161, and consequently, to use spacers 162 with a smaller height dimension. The spacers 162 are arranged at appropriate intervals along the longitudinal direction of the support anchor 161.

[0063] Here, the symbol M1 shown in Figure 12 refers to the end mesh located at the very tip, based on the direction in which the tunnel portal side projection 15B of the wire mesh 15 protrudes laterally from the ground side flanges 111b and 112b. The end mesh M1 of the tunnel portal side projection 15B corresponds to the overlap that overlaps with the tunnel face side projection 15A of the wire mesh 15 in the existing section closest to the tunnel face 8 in the axial direction of the tunnel T (the existing section where the tunnel support structure 10 was erected just before). The end mesh M1 of the tunnel portal side projection 15B of the wire mesh 15, while overlapped with the tunnel face side projection 15A in the existing section, may be appropriately bound with binding wire or other wires, or integrated by welding, etc., before the spraying of secondary concrete onto the tunnel interior surface. Furthermore, the support anchors 161 are set to a length that does not interfere with tunnel support structures 10 adjacent to existing ones when erecting tunnel support structures 10 in the newly constructed section, thereby ensuring good constructability.

[0064] Furthermore, the support anchors 161 are provided at predetermined intervals along the longitudinal direction of the first main body 111 and the second main body 112, thereby allowing the planar wire mesh 15 (protruding portion 15B on the tunnel entrance side) to be suitably supported from below. In addition, the support anchors 161, like the wire mesh 15, are embedded in the secondary concrete when the secondary concrete is sprayed onto the tunnel interior. Therefore, the support anchors 161 also function as crack prevention members for the secondary sprayed concrete layer 6. Furthermore, since the support anchors 161 are embedded in the secondary sprayed concrete layer 6, they are anchored to the secondary sprayed concrete layer 6. Therefore, the support anchors 161 also function as anchoring members that anchor the tunnel support structure 10 to the secondary sprayed concrete layer 6. Note that the support anchors 161 may also be headed anchors with an enlarged head at their tip, and such configuration can further enhance the anchoring force to the secondary sprayed concrete layer 6.

[0065] Next, returning to Figure 11, we will describe the details of the wire mesh 15 at the upper ends of the left steel support structure 10L (first main body 111) and the right steel support structure 10R (second main body 112). In Figure 11, the reference numeral M2 indicates the end mesh of the wire mesh 15 provided on the left steel support structure 10L, which is located at the very front in the longitudinal direction of the left steel support structure 10L (first main body 111). The reference numeral M3 indicates the end mesh of the wire mesh 15 provided on the right steel support structure 10R, which is located at the very front in the longitudinal direction of the right steel support structure 10R (second main body 112). In the example shown in Figure 11, the end mesh M2 of the wire mesh 15 provided on the left steel support structure 10L extends beyond the first top joint plate 121. The end mesh M2 of the wire mesh 15 is With the left-side steel support structure 10L and the right-side steel support structure 10R connected, the end mesh M3 of the wire mesh 15 provided on the right-side steel support structure 10R overlaps with the other end meshes. The end meshes M2 and M3 may be integrated as appropriate by binding wire, wire, or welding before spraying secondary concrete onto the tunnel interior surface.

[0066] The tunnel support structure 10, consisting of a left-side steel support structure 10L and a right-side steel support structure 10R configured as described above, is equipped with a guide member 14, allowing the left-side steel support structure 10L and the right-side steel support structure 10R to be easily connected. Specifically, when connecting the left-side steel support structure 10L and the right-side steel support structure 10R, as the first top joint plate 121 and the second top joint plate 122 are brought closer together, the inclined portion 142 of the guide member 14 guides the face-side edge 122f of the second top joint plate 122, thereby aligning the relative positions of the female connector 40 and the male connector 50 (male locking member 51) in the tunnel axis direction. Furthermore, since the projection dimension of the straight portion 141 relative to the first top joint plate 121 is equal to or greater than the projection length of the male locking member 51 relative to the second top joint plate 122, the alignment of the female connecting portion 40 and the male locking member 51 in the tunnel axial direction can be completed before the male locking member 51 collides with the outer surface 121a of the first top joint plate 121.

[0067] Here, when the operator of the erector device 100 operates each hand 18L, 18R by visual inspection, it is difficult to visually confirm the misalignment of the female connector 40 and the male connector 50 (male locking member 51) in the tunnel axis direction. In contrast, with the guide member 14 of this embodiment, the alignment of the female connector 40 and the male connector 50 (male locking member 51) in the tunnel axis direction can be easily performed, thus enabling smooth connection of the support structure.

[0068] Furthermore, in this embodiment, as shown in Figures 11 and 13, the guide member 14 is provided only on the face-side edge 121f of the first top joint plate 121, and no guide members are provided on any of the other side edges of the first top joint plate 121, namely the upper edge 121c, the lower edge 121d, and the tunnel entrance-side edge 121e. By not installing a guide member on the upper edge 121c of the first top joint plate 121, collision between the guide member and the wire mesh 15 (especially the end mesh M3) on the right-side steel support 10R side can be avoided when the support structure is connected, and deformation and damage to the wire mesh 15 (especially the end mesh M3) can be suitably suppressed. Furthermore, by not installing guide members on the lower edge 121d and the portal side edge 121e of the first top joint plate 121, the operator of the erector device 100 can more easily visually check the relative positions of the female connector 40 and the male connector 50 when connecting the shoring, enabling smooth connection of the shoring.

[0069] In the examples shown in Figures 11 and 13, a guide member 14 including a straight section 141 and an inclined section 142 has been described, but the guide member 14 is not limited to this embodiment. For example, as shown in the modified example in Figure 14, the guide member 14 may be formed by the straight section 141 alone. Also, the guide member 14 in this embodiment may be formed from a material other than a metal plate. For example, as shown in the modified example in Figure 15, the guide member 14 may be formed from a rod-shaped member. The rod-shaped member forming the guide member 14 may be a reinforcing bar. In this case, the straight section 141 and the inclined section 142 can be easily formed by bending the reinforcing bar from the middle.

[0070] Furthermore, in the example shown in Figure 11, the wire mesh 15 provided on the left steel support structure 10L is slightly bent diagonally upward from the base of the end mesh M2, so that the end mesh M2 is inclined diagonally upward. This makes it less likely for the end mesh M2 of the wire mesh 15 on the left steel support structure 10L side and the end mesh M3 of the wire mesh 15 on the right steel support structure 10R side to collide head-on when the support structures are connected. This effectively suppresses deformation and damage to the wire mesh 15 caused by such collisions, and enables smooth connection of the support structures.

[0071] In this embodiment, the guide member 14 only needs to be provided on the face-side edge of either the first top joint plate 121 or the second top joint plate 122. This allows the guide member to guide the face-side edge of the other of the first top joint plate 121 or the second top joint plate 122 during the connection of the shoring, thereby assisting in the insertion operation of the male connector 50 into the female connector 40. Therefore, although Figures 11 to 13 show an example in which the guide member 14 is installed on the face-side edge 121f of the first top joint plate 121, the guide member 14 may instead be installed on the face-side edge 122f of the second top joint plate 122. In that case, it is preferable to install the guide member 14 only on the face-side edge 122f of the second top joint plate 122.

[0072] Although embodiments of the present invention have been described above, the aspects disclosed in each embodiment can be combined as much as possible. [Explanation of Symbols]

[0073] 10. Tunnel support work 10L...Left side steel shoring 10R...Steel shoring on the right side 14. Guide member 15. Wire mesh 40...Female connection part 50...Male connection part 51...Male locking member 121...First top joint plate 122...Second top joint plate

Claims

1. A tunnel support structure applied to the NATM method, comprising first and second arc-shaped divided steel support structures erected along the tunnel wall formed by tunnel excavation, wherein the top ends of each support structure are interconnected while being held by a pair of hands in an erector device, The first steel support structure has a first top joint plate provided at the top end and a single female connector recessed in only one location on the first top joint plate. The second steel support structure has a second top joint plate provided at the top end, and a single male connector that is recessed in only one location on the second top joint plate and is locked in place by being inserted into the single female connector. The single female connector is positioned eccentrically near the side edge with respect to the widthwise center of the first top joint plate so as not to interfere with the web of the first steel support structure. The single male connector is positioned eccentrically near the side edge with respect to the widthwise center of the second top joint plate, so as not to interfere with the web of the second steel support structure. A tunnel support structure having a single-pronged connecting structure that connects the single female connecting portion and the single male connecting portion.

2. The single female connector is eccentrically positioned near the side edge of the tunnel entrance with respect to the widthwise center of the first top joint plate. The single male connector is eccentrically positioned near the side edge of the tunnel entrance, with reference to the center of the second top joint plate in the width direction. The tunnel support structure according to claim 1.

3. In the first and second steel support structures, wire mesh is fixed along the ground-side flange so as to protrude laterally from the face-side edge and the tunnel entrance-side edge of the ground-side flange. A guide member is provided on the face-side edge of either the first top joint plate or the second top joint plate, which assists the insertion operation of the single male connector into the single female connector by guiding the face-side edge of the other of the first top joint plate or the second top joint plate when connecting the shoring. The guide member is located at the cutting edge of one of the first top joint plate and the second top joint plate. It is provided only on the wing-side edges. The tunnel support structure according to claim 1 or 2.

4. A method for connecting tunnel support structures as described in any one of claims 1 to 3, The first and second steel supports are gripped by a pair of hands in the erector device, and the pair of hands are operated to connect the first and second steel supports by inserting the single male connector into the single female connector. Shoring connection method.

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