Box-type connecting structure and method for constructing connecting boxes

Abstract

To solve the problems faced by the conventional technology, namely, to provide a technology that can easily connect boxes of adjacent tunnels.SOLUTION: A box connection structure of the present invention is a structure in which two or more individual box bodies constructed in the ground are connected to connect adjacent individual box bodies, and comprises a joint material and a corner body. By inserting flanges into flange grooves of the individual boxes of the adjacent preceding individual box and succeeding individual box, and inserting a part of a web plate into a web plate groove of each of the preceding individual box and the succeeding individual box, the preceding individual box and the succeeding individual box are connected by the joint material.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present invention relates to a technology for forming an underground space by a lining body composed of a plurality of box bodies, and more specifically, relates to a structure for connecting adjacent box bodies, and a connected box body construction method for constructing a connected box body using the structure.

Background Art

[0002] Road tunnels, underground railway tunnels, common ducts that collectively house power lines and the like in urban areas are usually installed underground beneath roads. Such road tunnels and the like are generally constructed by installing an underground starting section and an underground arrival section in advance, and then utilizing a tunnel excavated by a jacking method or a shield method. In many cases, road tunnels and the like are constructed by excavating one tunnel, in other words, by providing one through-hole in the ground.

[0003] In contrast, large-diameter road tunnels (especially branching and merging sections), underground malls, subway station sections and the like require a considerable underground space for arranging various facilities such as stores and platforms in addition to pedestrian passages, and therefore construction of a tunnel having a large-scale inner cross-section is required. However, there is a limit to the cross-sectional area that can be excavated by the jacking method or the shield method, and it is difficult to secure a large-scale space such as an underground mall only by excavating a single tunnel.

[0004] Therefore, when forming such a large-scale space underground, a tunnel structure as shown in Figure 16 may be adopted. In the tunnel structure shown in this figure, a lining body LN composed of a plurality of (19 in the figure) box bodies PB is formed, and this lining body LN supports the load from the natural ground to secure a stable underground space US. Hereinafter, the procedure for forming the lining body LN as shown in Figure 16 will be described.

[0005] First, as shown in Figure 17(a), the first tunnel is constructed by excavating using a pipe jacking method or shield tunneling method while installing multiple box-shaped PB structures aligned along the tunnel axis. Since box-shaped PB structures are often rectangular (especially square), it is advisable to use a machine capable of excavating rectangular cross-sections for excavation. Once the first tunnel is constructed, the second tunnel is constructed adjacent to it in the same manner as the first tunnel. At this time, the box-shaped PB structures of the second tunnel are installed while being connected to (or later connected together with) the box-shaped PB structures of the first tunnel. Then, by repeating this tunnel construction a predetermined number of times (19 in the case of Figure 16), a ring-shaped lining LN consisting of multiple (19 in the case of Figure 16) box-shaped PB structures is formed. Furthermore, as shown in Figure 17(b), a space SP is formed inside the box-shaped PB structures, so main reinforcement and distribution reinforcement are installed in this space SP, and then concrete is poured. Through these processes, a reinforced concrete lining LN is formed, and a stable underground space US is secured.

[0006] As described above, in forming the tunnel lining LN, it is necessary to connect the box pallets PB of adjacent tunnels. Conventionally, the mainstream method for connecting box pallets PB has been a connection structure using long bolts LB, as shown in Figure 18. The box pallets PB are connected by inserting the long bolts LB through the box pallets PB of both tunnels and tightening the bearing plates (plates) placed at both ends of the long bolts LB with nuts. For example, Patent Document 1 proposes a structure in which the box pallets PB are in contact with each other, but the joint surface is connected with reinforcing bars, similar to Figure 18. Non-Patent Document 1 discloses the "MMST method (Multi-Micro Shield Tunneling Method)," which also has a structure similar to Figure 18, but is a structure in which the box pallets PB are connected while separated. Note that while Patent Document 1 connects at the position of the main girder at the joint surface, the MMST method connects at the corner instead of the main girder.

[0007] In addition to the connection technology shown in Figure 18, various other technologies for connecting box bodies PB have been proposed. For example, Patent Document 2 proposes a technology for connecting the two box bodies by inserting the protruding portion 3 of the subsequent box body into the groove portion 2 of the preceding box body. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Patent No. 5351676 [Patent Document 2] Japanese Patent Publication No. 2011-256538 [Non-patent literature]

[0009] [Non-Patent Document 1] "Member Experiments on Tunnel Structures Using the MMST Method (58th Annual Scientific Conference of the Japan Society of Civil Engineers, September 2003)" [Overview of the project] [Problems that the invention aims to solve]

[0010] By the way, conventional connection technologies, such as the connection technology shown in Figure 18 and the connection technology disclosed in Patent Document 1, depended on the relative arrangement of the box pallets PB of adjacent tunnels (hereinafter simply referred to as "relative arrangement"). That is, if the relative arrangement is as planned (or in cases where the error from the plan is extremely small), it becomes possible to insert the long bolts LB or to insert the protruding sections 3, and as a result, the two box pallets can be connected. On the other hand, when the box pallets PB of adjacent tunnels are arranged with a large error from the plan, that is, when there is a considerable "deviation" in the relative arrangement, it becomes impossible to insert the long bolts LB or to insert the protruding sections 3, and as a result, the two box pallets PB cannot be connected. When it is not possible to connect the two box pallets PB, it is necessary to adjust the position of one of the box pallets PB, but performing such adjustment work underground in an extremely narrow environment requires considerable effort and time, and is an extremely difficult task.

[0011] The object of the present invention is to solve the problems of the prior art, namely, to provide a technology that allows for easy connection of the box structures of adjacent tunnels. [Means for solving the problem]

[0012] The present invention focuses on the fact that individual box bodies can be easily connected to each other by inserting an H-shaped joint material into a flange groove provided on the side surface of the individual box body, and that the clearance (so to speak, play) provided between the flange groove and the joint material absorbs misalignment in relative positioning. This invention is based on an unprecedented idea.

[0013] The box-shaped connecting structure of the present invention is a structure for connecting adjacent individual box-shaped bodies in a connected box-shaped structure which is constructed underground and consists of two or more individual box-shaped bodies, and comprises a joint material and a corner body. The joint material connects adjacent preceding individual box-shaped bodies and succeeding individual box-shaped bodies, and the corner body is provided at the corner of the preceding individual box-shaped body and succeeding individual box-shaped body. The preceding individual box-shaped body and succeeding individual box-shaped body, which have a roughly rectangular cross-section (including a rectangle), have an opening in the center of the cross-section, and a main girder is arranged around the opening. The joint material, which has an H-shaped cross-section, consists of a web plate and flanges arranged at both ends of the web plate, and the corner body consists of a corner main girder plate with a flange groove and a joint receiving member with a web plate groove. Then, flanges are inserted into the flange grooves of the adjacent preceding and succeeding individual box bodies, and a portion of the web plate is inserted into the web plate grooves of the preceding and succeeding individual box bodies, thereby connecting the preceding and succeeding individual box bodies with a joint material.

[0014] The box-type connecting structure of the present invention can also be configured such that the corner main girder plates are positioned at the locations of the central main girder and the side main girder. In this case, the main girder is composed of side main girders positioned at the front and rear in the tunnel axis direction, and a central main girder positioned between the front side main girder and the rear side main girder.

[0015] The box-type connecting structure of the present invention may further include an opening cover. This opening cover consists of a contact plate wider than the web plate groove and a projection attached to the contact plate that is narrower than the web plate groove. The projection is insertable into the flange groove and the web plate groove, and the opening cover is removable from the flange groove and the web plate groove, allowing a joint material to be installed in the flange groove and web plate groove from which the opening cover has been removed.

[0016] The box-type connecting structure of the present invention can also have a tapered shape in which the web plate groove of the joint support member widens outward in cross-sectional view.

[0017] The box-type connecting structure of the present invention can also have a tapered shape in which the flange of the joint material becomes narrower towards the tip.

[0018] The box-shaped connecting structure of the present invention may also be provided with a notch in the joint support member. This notch is formed by cutting a part of the joint support member in the direction of the tunnel axis. In this case, the corner main girder plate is positioned in a location where no notch is provided, and the tunnel axis length of the joint member is shorter than the tunnel axis length of the notch.

[0019] The box-shaped connecting structure of the present invention may also include a main girder that includes side main girders and a central main girder. These side main girders are positioned at the front and rear in the tunnel axis direction, and the central main girder is positioned between the front and rear side main girders. In this case, the notch is formed between the central main girder and the side main girders, and the corner main girder plates are positioned at the positions of the central main girder and the side main girders.

[0020] The present invention provides a method for constructing a connected box structure underground, comprising a step for installing a preceding individual box structure, a step for installing a succeeding individual box structure, and a connecting step. In the preceding individual box structure installation step, the preceding individual box structure is installed while excavating the ground, and in the succeeding individual box structure installation step, the succeeding individual box structure is installed while excavating the ground so as to be adjacent to the preceding individual box structure. In the connecting step, adjacent preceding and succeeding individual box structures are connected by joint materials and corner bodies. In the connecting step, flanges are inserted into the flange grooves of the preceding and succeeding individual box structures, and a portion of the web plate is inserted into the web plate grooves of the preceding and succeeding individual box structures.

[0021] The method for constructing connected box bodies according to the present invention can also be a method that utilizes opening cover material. This opening cover material is insertable into the flange groove and web plate groove of the corner body and is removable. In this case, in the preceding individual box body installation step, the preceding individual box body is installed with the opening cover material installed in the flange groove and web plate groove, and in the subsequent individual box body installation step, the subsequent individual box body is installed with the insertable opening cover material installed in the flange groove and web plate groove. In the connecting step, the insertable opening cover material is removed from the flange groove and web plate groove before installing the joint material.

[0022] In the connected box structure construction method of the present invention, the joint material can also be pulled while causing the flange groove and the web groove to travel in the tunnel axial direction by a traction device installed at the underground launching section (or the underground arriving section).

[0023] The connected box structure construction method of the present invention can further include a corner formwork installation step and a filling step. In the corner formwork installation step, the corner formwork is installed so as to cover two or more corner main girder plates. In the filling step, a filler is filled into a space surrounded by the corner formwork and the two or more corner main girder plates, in which a part of the joint material is arranged. The main girders in this case include side main girders disposed at the front and rear in the tunnel axial direction, and a central main girder disposed sandwiched between the front and rear side main girders, and the corner main girder plates are disposed at the positions of the central main girder and the side main girders.

[0024] The connected box structure construction method of the present invention can also be a method of inserting the web into the web groove and inserting a part of the flange into the flange groove while inserting the joint material from the notch portion. Effects of the Invention

[0025] The box connection structure and the connected box structure construction method of the present invention have the following effects. (1) Only by inserting the joint material into the flange groove and the web groove, the subsequent individual box can be installed at an appropriate position, and adjacent boxes can be connected to each other, that is, the construction labor can be reduced as compared with the prior art. (2) Due to the effect of providing a clearance (so-called play) between the flange groove and the joint material, even if a certain degree of deviation occurs in the relative arrangement of the preceding individual box and the subsequent individual box, the joint material can be inserted into the flange groove and the web groove, that is, the preceding individual box and the subsequent individual box can be connected. (3) Further, by forming the web groove of the joint receiving material into a tapered shape that expands outward in cross-sectional view, or forming the flange of the joint material into a tapered shape that becomes narrower toward the tip, the deviation in the relative arrangement of the preceding individual box and the subsequent individual box can be further absorbed. (4) By appropriately designing the steel materials that constitute the individual box bodies, that is, by selecting steel materials of the appropriate material (e.g., SM570), shape, and dimensions, individual box bodies with the desired rigidity and strength can be obtained. As a result, a connected box body consisting of multiple individual box bodies can be evaluated as a permanent structure. (5) Furthermore, since the rigidity of the connecting box structure (especially the steel members) is properly evaluated, there is no need to place main reinforcement bars in the space within the individual box structure, which improves work efficiency compared to conventional technology. (6) Furthermore, since it is not necessary to design the connecting box structure as a reinforced concrete structure, the beam height (beam depth) of the connecting box structure can be reduced, which in turn reduces the amount of concrete to be poured and the amount of excavation required, thereby lowering the overall construction cost. [Brief explanation of the drawing]

[0026] [Figure 1] (a) is a schematic cross-sectional view showing the connecting box, and (b) is a schematic longitudinal section showing a part of the connecting box. [Figure 2] (a) is a front view of an individual box structure as seen in the direction of the tunnel axis, (b) is a cross-sectional view taken along arrow AA showing a part of the wall of an individual box structure, and (c) is a cross-sectional view taken along arrow BB showing a part of the wall of an individual box structure. [Figure 3] (a) is a cross-sectional side view of an individual box with a skin plate installed, and (b) is a cross-sectional side view of an individual box with the skin plate removed. [Figure 4] A schematic cross-sectional view showing the left individual box and the right individual box connected by the box-connecting structure of the present invention. [Figure 5] (a) is a schematic front view showing the corner body as seen in the tunnel axis direction, and (b) is a schematic side view showing the corner body as seen in the transverse direction. [Figure 6] (a) is a schematic cross-sectional view of the joint material, (b) is a schematic plan view of the joint material, and (c) is a schematic perspective view of the joint material. [Figure 7](a) is a schematic partial front view showing the left and right individual boxes connected by a joint, and (b) is a schematic partial perspective view showing the left and right individual boxes connected by a joint. [Figure 8] (a) is a schematic front view showing a tapered corner body as seen in the direction of the tunnel axis, (b) is a schematic cross-sectional view showing a tapered joint material, and (c) is a schematic front view showing a state in which the left individual box body and the right individual box body, which have a vertical displacement, are connected by a tapered corner body and joint material. [Figure 9] (a) is a schematic front view showing the notch of the joint support member as seen in the transverse direction, and (b) is a schematic side view showing the notch of the joint support member as seen in the tunnel axis direction. [Figure 10] (a) is a schematic cross-sectional view showing how the joint material is inserted into the notch from below, and (b) is a partial perspective view showing multiple joint materials intermittently arranged in the tunnel axis direction. [Figure 11] (a) is a schematic perspective view showing the opening cover material, and (b) is a schematic partial front view showing the opening cover material. [Figure 12] A flowchart showing the main steps of the method for constructing a connected box according to the present invention. [Figure 13] A front view of the connection section, where ground improvement work has been carried out, as seen in the direction of the tunnel axis. [Figure 14] A schematic perspective view showing individual casings with the skin plates removed. [Figure 15] A schematic perspective view showing the installation of corner formwork at corners. [Figure 16] A schematic cross-sectional view showing the lining structure, which consists of 19 box-shaped structures, and the underground space secured by the lining structure. [Figure 17] (a) is a schematic longitudinal section showing multiple box structures arranged in the direction of the tunnel axis, and (b) is a schematic perspective view showing adjacent box structures in the cross-sectional direction. [Figure 18] A cross-sectional view showing adjacent box bodies connected using connecting bolts. [Modes for carrying out the invention]

[0027] An example of the box-type connecting structure and the method for constructing the connecting box-type structure of the present invention will be explained with reference to the figures.

[0028] 1.Overview Figure 1 is a schematic diagram of the connected box structure 100, where (a) is a cross-sectional view cut in a vertical plane, and (b) is a longitudinal section showing a part of the connected box structure 100. As shown in Figure 1(a), the connected box structure 100 is a structure in which multiple (19 in the figure) box structures (hereinafter referred to as "individual box structures 200" for convenience) are connected, and by supporting loads from the surrounding ground (that is, by functioning as a lining), it can form a stable underground space US.

[0029] As shown in Figure 1(b), a tunnel structure (hereinafter referred to as "unit tunnel 110" for convenience) is formed by the continuous arrangement of multiple individual box bodies 200. This unit tunnel 110 is constructed by excavating using the pipe jacking method or shield tunneling method after providing an underground launching section (e.g., launching shaft) and an underground receiving section (e.g., receiving shaft), and continuously arranging hollow individual box bodies 200. In other words, the connected box body 100 is a three-dimensional structure composed of multiple (19 in Figure 1) unit tunnels 110, and the underground space US is formed as a tunnel with a large cross-section. For convenience, as shown in Figure 1, the axial direction of the tunnel (unit tunnel 110 or underground space US) will be referred to as the "tunnel axis direction," and the horizontal direction perpendicular to this tunnel axis direction will be referred to as the "transverse direction."

[0030] 2.Case connection structure The box-connecting structure of the present invention will now be described. The method for constructing a connected box of the present invention is a method for constructing a connected box 100 using the box-connecting structure of the present invention. Therefore, the box-connecting structure of the present invention will be described first, followed by the method for constructing a connected box of the present invention.

[0031] Figure 2 is a schematic diagram of the individual box structure 200, where (a) is a front view seen in the direction of the tunnel axis, (b) is a cross-sectional view taken along arrow AA (Figure 1(a)) showing a part of the wall that constitutes the individual box structure 200, and (c) is a cross-sectional view taken along arrow BB (Figure 1(a)) showing a part of the wall. Figure 3 is a side view of the individual box structure 200 seen in the transverse direction, where (a) shows the state with the skin plate 220 installed and (b) shows the state with the skin plate 220 removed.

[0032] As shown in Figures 2(a) and 3, the individual box-shaped structure 200 has a roughly rectangular cross-section (including a rectangle) and a generally box-like shape with a space (hereinafter referred to as the "opening") inside. More specifically, the individual box-shaped structure 200 is formed by connecting four wall bodies arranged on the top, bottom, left, and right sides at their respective ends, and these four wall bodies form an opening that penetrates in the direction of the tunnel axis. In other words, four wall bodies are arranged around the opening. For example, the individual box-shaped structure 200 can be designed with a length (transverse direction) of 5m, a width (in the direction of the tunnel axis) of 1m, and a height of 2.5m.

[0033] Each wall surrounding the opening is formed by a main girder 210 and a skin plate 220. More specifically, the wall on the left side (hereinafter referred to as the "left wall") and the wall on the right side (hereinafter referred to as the "right wall") are formed by a main girder 210 and a skin plate 220, as shown in Figure 2(b), with the skin plate 220 attached to the main girder 210, which extends roughly the entire length of the left wall (right wall), by welding or other means. The wall above (hereinafter referred to as the "upper wall") and the wall below (hereinafter referred to as the "lower wall") have a similar configuration to the left and right walls, as shown in Figure 2(c). As will be described later, the skin plate 220 will be removed during construction (Figure 3(b)), so it is preferable to attach the skin plate 220 to the main girder 210 using a method that allows for relatively easy removal. The main girder 210 can be made of steel material such as steel plates, and the skin plate 220 can also be made of steel material such as steel plates.

[0034] The main girder 210 that constitutes the wall can be formed by a central main girder 211 and side main girders 212. For example, as shown in Figure 3(b), the main girder 210 can be formed by side main girders 212 positioned at the front and rear in the tunnel axis direction, respectively, and a central main girder 211 positioned between these side main girders 212 (i.e., near the middle in the tunnel axis direction). Alternatively, the main girder 210 can be formed by various combinations of the central main girder 211 and side main girders 212 (such as the number of central main girders 211 and side main girders 212 arranged), such as forming the main girder 210 with only the central main girder 211, or forming the main girder 210 with only the front and rear side main girders 212.

[0035] Naturally, the individual box bodies 200 are designed to withstand various anticipated loads. Specifically, the length, width, and height dimensions of the individual box bodies 200 are determined based on design calculations, and the specifications of the wall bodies (left wall, right wall, upper wall, and lower wall) such as materials and dimensions are also determined based on design calculations. In particular, the main girders 210 that constitute the wall bodies are the members that primarily bear external forces during service, so the material of the steel used (e.g., SM570), as well as the thickness and width dimensions, are designed in detail. For example, by designing the main girders 210 to have considerable rigidity and strength, the connected box bodies 100, in which concrete is finally filled into the openings, can be made of unreinforced concrete with the arrangement of structural reinforcement omitted, or of concrete with only shear reinforcement among the structural reinforcement bars.

[0036] Figure 4 is a schematic cross-sectional view showing a state in which adjacent individual casings 200 are connected by the casing connecting structure 300 of the present invention. The individual casings 200 that constitute the connecting casing 100 may be adjacent to each other horizontally, vertically, or diagonally, as shown in Figure 1, but for convenience, the example in which the individual casings 200 are adjacent horizontally will be explained here.Therefore, as shown in Figure 4, the one located on the left of the two adjacent individual casings 200 (for example, the preceding individual casing 200) will be called the left individual casing 200L, and the one located on the right (for example, the succeeding individual casing 200) will be called the right individual casing 200R.

[0037] The box-type connecting structure 300 of the present invention is composed of a corner body 310 and a joint material 320, as shown in Figure 4, and can also be composed of an opening cover material, which will be described later. The corner body 310 is provided at the end (i.e., the corner) where four walls (left wall, right wall, upper wall, and lower wall) of the individual box-type 200 are connected, as shown in Figure 2(a).

[0038] The following will provide a detailed explanation of each of the main elements constituting the box-type connecting structure 300 of the present invention.

[0039] (Corner body) Figure 5 is a schematic diagram of the corner body 310, where (a) is a cross-sectional front view seen in the tunnel axis direction, and (b) is a partial side view seen in the transverse direction from the opening side. As shown in Figure 5(a), the corner body 310 is composed of a corner main girder plate 311 and a joint support member 312. As shown in Figure 5(b), the plate-shaped corner main girder plate 311 is installed in accordance with the arrangement positions of the central main girder 211 and the side main girder 212 (that is, it is arranged with spacing in the axial direction of the individual box body 200), and the columnar or annular joint support member 312 is arranged generally over the entire width direction (tunnel axis direction) of the wall body. The corner main girder plate 311 can be made of steel material such as flat steel or steel plate, and the joint support member 312 can also be made of steel material such as steel plate or steel pipe.

[0040] Furthermore, the corner main girder plate 311 is provided with a space (hereinafter referred to as "flange groove 311G") that can accommodate the flange 322 of the joint material 320, which will be described later, and the joint support member 312 is provided with a space (hereinafter referred to as "web plate groove 312G") that can accommodate the web plate 321 of the joint material 320, which will also be described later. For example, the flange groove 311G can be formed by hollowing out a part of the central part of the plate-shaped corner main girder plate 311, and the web plate groove 312G (i.e., the gap) can be formed by arranging the upper joint support member 312 (hereinafter referred to as "upper support member 312T") and the lower joint support member 312 (hereinafter referred to as "lower support member 312B") with a gap between them. In other words, a continuous groove-shaped web plate groove 312G is formed in one corner body 310, and flange grooves 311G are formed for each central main girder 211 and side main girder 212 installed. However, each flange groove 311G is in communication with the web plate groove 312G, and the height dimension of the flange groove 311G (vertical dimension in Figure 5(a)) is formed to be larger (longer) than the width dimension of the web plate groove 312G (vertical dimension in Figure 5(a)).

[0041] (joint material shop) Figure 6 is a schematic diagram of the joint material 320 that constitutes the connecting box 100, where (a) is a cross-sectional view, (b) is a plan view seen from above, and (c) is a perspective view. As shown in this figure, the joint material 320 is composed of a web plate 321 and two flanges 322 positioned at both ends of the web plate 321, and as can be seen from Figure 6(a), the cross-sectional view is H-shaped. This joint material 320 is formed from a material with considerable strength, such as steel or synthetic resin, and can be manufactured, for example, by processing a steel plate (such as welding and fixing parts or cutting out parts), or by using I-beams or H-beams.

[0042] As previously described, the connecting box structure 100 is a three-dimensional structure composed of multiple unit tunnels 110. The procedure for constructing this connecting box structure 100 will be described in detail later, but it involves constructing each unit tunnel 110 as it is being built. More specifically, the first unit tunnel 110 is constructed from the underground launching section to the underground reaching section, and then the subsequent unit tunnel 110 is constructed adjacent to that unit tunnel 110 (i.e., the preceding unit tunnel 110). As a result, two unit tunnels 110 are placed side by side, and the individual box structures 200 that make up each unit tunnel 110 are placed adjacent to each other. When connecting these two adjacent individual box structures 200, the joint material 320 shown in Figure 6 is used. By repeating this series of steps (construction of unit tunnels 110 ~ connection of individual box structures 200), the connecting box structure 100 shown in Figure 1(a) is constructed.

[0043] Figure 7 schematically shows a left individual box 200L and a right individual box 200R connected by a joint material 320, where (a) is a partial front view in the direction of the tunnel axis and (b) is a partial perspective view. As shown in this figure, the joint material 320 connects two adjacent individual box 200s by engaging with the corner body 310 of one individual box 200 (for example, the left individual box 200L) and with the corner body 310 of the other individual box 200 (for example, the right individual box 200R). More specifically, the left flange 322 of the joint material 320 is inserted into the flange groove 311G of the left individual box casing 200L, and a portion of the web plate 321 of the joint material 320 is inserted into the web plate groove 312G of the left individual box casing 200L. Similarly, the right flange 322 of the joint material 320 is inserted into the flange groove 311G of the right individual box casing 200R, and a portion of the web plate 321 of the joint material 320 is inserted into the web plate groove 312G of the right individual box casing 200R, thereby connecting the left individual box casing 200L and the right individual box casing 200R. Therefore, the joint material 320 should be installed, for example, so as to slide in the axial direction of the tunnel from the tunnel entrance side (underground launching section side). When the joint material 320 is installed, as will be described later with reference to Figure 15, it is advisable to fill the four corner sections with cement-based filler material (for example, high-strength mortar or concrete) so that the joint material 320 and the individual box body 200 (especially the flange 322 and the corner section) become integrated.

[0044] When connecting the left individual box 200L and the right individual box 200R, one joint material 320 can be installed for each pair of individual box 200 (left individual box 200L and right individual box 200R), or two or more joint materials 320 can be installed. For example, if the width dimension (dimension in the tunnel axis direction) of the walls of the left individual box 200L and the right individual box 200R is 1m each, then when using a joint material 320 with a length dimension (vertical dimension in Figure 6(b)) of 1m, only one can be installed, while when using a joint material 320 with a length dimension of 0.5m, two can be installed so that they are aligned in the tunnel axis direction.

[0045] Incidentally, as previously mentioned, the left individual box 200L and the right individual box 200R may be positioned with a considerable error from the plan, that is, with a considerable "deviation" in their relative position. The "deviation" referred to here includes differences in the tunnel axis direction (i.e., horizontal deviation) and differences in the height direction (i.e., vertical deviation) that occur between the left individual box 200L and the right individual box 200R. In this case, if there is no gap (clearance) between the flange 322 and the flange groove 311G, or between the web plate 321 and the web plate groove 312G (or if it is extremely small), it may not be possible to install the joint material 320 due to the deviation in relative position, and as a result, the left individual box 200L and the right individual box 200R cannot be properly connected. Therefore, it is advisable to design the dimensions of the flange 322 and web plate 321 (especially the height and thickness), and the dimensions of the flange groove 311G and web plate groove 312G (especially the groove height and width), so that a considerable clearance (so to speak, play) is formed between the flange 322 and the flange groove 311G, and between the web plate 321 and the web plate groove 312G. This way, even if there is some misalignment in the relative positions, the clearance will absorb that misalignment, and as a result, the joint material 320 can be installed, that is, the left individual box 200L and the right individual box 200R can be connected.

[0046] (Tapered corner body) As described above, even if there is a certain degree of "misalignment" in the relative position of the left individual box 200L and the right individual box 200R, the joint material 320 can be installed by providing clearance between the flange 322 and the flange groove 311G, and clearance between the web plate 321 and the web plate groove 312G, thereby connecting the left individual box 200L and the right individual box 200R. However, there is a limit to the relative positional misalignment that can be absorbed by these clearances. Therefore, in cases where a considerable degree of misalignment is expected, it is advisable to use a tapered corner body 310 as shown in Figure 8(a). Figure 8(a) is a schematic partial front view showing a tapered corner body 310 as seen in the tunnel axis direction.

[0047] The tapered corner body 310 has a tapered shape in which its web groove 312G widens outward (to the right in the figure), as shown in Figure 8(a). More specifically, when the web groove 312G is viewed in cross-section (cut in a vertical cross section in the transverse direction), it has a tapered shape in which the size of the opening (vertical width in the figure) gradually increases outward from the opening side (left in the figure) of the individual box body 200. Although this figure shows an example where the tapered shape of the web groove 312G is linear, it is not limited to this and can also be a curved tapered shape (so-called R-processing).

[0048] By using the tapered corner body 310, even if there is a considerable "misalignment" in the relative position of the left individual box body 200L and the right individual box body 200R, the joint material 320 can be inserted into the flange groove 311G or the web groove 312G. For example, in Figure 8(c), there is a vertical misalignment between the left individual box body 200L and the right individual box body 200R, but due to the tapered shape of the web groove 312G of the corner body 310, the joint material 320 can be inserted into the flange groove 311G or the web groove 312G while tilted vertically (tilted downwards to the right in the figure).

[0049] (Tapered joint material) The joint material 320 shown in Figure 6(a) has a square-shaped flange 322 at its tip (upper and lower ends in the figure). When using such a joint material 320, if there is a certain degree of "misalignment" in the relative position of the left individual box body 200L and the right individual box body 200R, the tip of the flange 322 may interfere with the corner main girder plate 311 of the corner body 310 or the main girder 210 of the individual box body 200, making it impossible to insert the joint material 320 into the flange groove 311G or the web plate groove 312G. Therefore, in cases where a considerable degree of misalignment is expected, it is advisable to use a tapered joint material 320 as shown in Figure 8(b). Figure 8(b) is a schematic cross-sectional view of a tapered joint material 320.

[0050] As shown in Figure 8(b), the tapered joint material 320 has a tapered shape in which its flange 322 becomes narrower towards the tip (upper and lower ends in the figure). Below, the tapered shape of the flange 322 will be described in detail, with the inner wall surface (the side facing the web plate 321) being referred to as the "inner surface" and the outer wall surface (the side opposite the web plate 321) being referred to as the "outer surface". When the flange 322 is viewed in cross-section, its inner surface slopes towards the outer surface as it moves away from the web plate 321 (towards the upper and lower ends in the figure), meaning that the thickness of the flange 322 (the dimension in the left-right direction in the figure) decreases as it moves away from the web plate 321 (towards the upper and lower ends). Note that this figure shows an example of a tapered shape in which the inner surface of the flange 322 slopes in a curved shape (so-called R-processing), but it is not limited to this, and the inner surface can also be tapered in a straight line.

[0051] By using the tapered joint material 320, the tip of the flange 322 is less likely to interfere with the corner main girder plate 311 or the main girder 210, making it easier to insert the joint material 320 into the flange groove 311G or the web plate groove 312G. For example, in Figure 8(c), there is a vertical misalignment between the left individual box body 200L and the right individual box body 200R. However, due to the tapered shape of the flange 322 of the joint material 320, even though the joint material 320 is inclined vertically, it can be inserted into the flange groove 311G or the web plate groove 312G without interfering with the corner main girder plate 311 or the like.

[0052] (Notched section) As shown in Figure 5, the corner body 310 has its joint support members 312 arranged across the entire width direction (tunnel axis direction) of the wall of the individual box body 200. Therefore, the web groove 312G of this corner body 310 is continuous in the tunnel axis direction. In other words, the web groove 312G is connected to the outside only at both ends (so to speak, both tunnel entrances), and it is not possible to approach the web groove 312G from the outside in between. Therefore, when installing the joint material 320, it is necessary to slide the joint material 320 from the tunnel entrance side in the tunnel axis direction by using a traction device such as a winch. However, if the length of the unit tunnel 110 (i.e., the length of the connecting box body 100) is considerably long, a traction device of considerable size will be required, and the installation of the joint material 320 will take time, and there is also a risk of problems such as the joint material 320 stopping midway while in motion. Therefore, especially in cases where the extension of the connecting box 100 is considerably long, it is advisable to provide a notch 313 in the joint receiving member 312 of the corner body 310, as shown in Figure 9.

[0053] The notch 313 is formed by cutting a portion of the joint support member 312 in the direction of the tunnel axis. For example, in Figure 9, the notch 313 is formed by cutting a portion of the lower part of the joint support member 312 (lower support member 312B in the figure). When a notch 313 is provided in the joint support member 312, the corner main girder plate 311 of the corner body 310 is installed in a position in the joint support member 312 where the notch 313 is not formed. For example, if the main girder 210 consists of a central main girder 211 and side main girders 212, it is preferable to form a notch 313 in the joint support member 312 between the central main girder 211 and the side main girder 212, and to install the corner main girder plate 311 at the installation positions of the central main girder 211 and the side main girder 212. In Figure 9, the notch 313 is formed by cutting out only the lower support member 312B of the joint support member 312. However, the notch 313 can also be formed by cutting out a part of the upper support member 312T in addition to (or instead of) the lower support member 312B.

[0054] Furthermore, when a notch 313 is provided in the joint support member 312, it is preferable to make the length dimension of the joint material 320 (the vertical dimension in Figure 6(b)) smaller (shorter) than the tunnel axis length of the notch 313. This allows the joint material 320 to be inserted from the notch 313, as shown in Figure 10(a), eliminating the need to slide the joint material 320 in the tunnel axis direction using a winch or the like. In the example in Figure 10(a), the joint material 320 is housed in the notch 313 (the part where the corner main girder plate 311 is not installed) from below, and with a part of the web plate 321 inserted into the web plate groove 312G, the joint material 320 can be positioned in the predetermined location, i.e., where the corner main girder plate 311 (i.e., the flange groove 311G) is installed, by sliding it in the tunnel axis direction (left-right direction in the figure). Therefore, in this case, the joint material 320 is not arranged continuously in the axial direction of the tunnel, but rather intermittently, as shown in Figure 10(b).

[0055] (Opening cover material) Figure 11 is a schematic diagram of the opening cover material 330 that constitutes the box-type connecting structure 300, where (a) is a perspective view and (b) is a partial front view in the direction of the tunnel axis. As shown in this figure, the opening cover material 330 is composed of a contact plate 331 and a projection 332 attached near the center of the contact plate 331. This opening cover material 330 is formed from a material such as steel or synthetic resin, and can be manufactured, for example, by processing steel plates or steel pipes. Furthermore, since the opening cover material 330 is housed in the flange groove 311G and the web plate groove 312G, the height dimension of the contact plate 331 (vertical dimension in Figure 11) is slightly smaller (narrower) than the height dimension of the flange groove 311G (vertical dimension in Figure 11), and the width dimension of the projection 332 (vertical dimension in Figure 11) is also slightly smaller (narrower) than the width dimension of the web plate groove 312G (vertical dimension in Figure 11). However, in order to prevent the opening cover material 330, which is housed in the flange groove 311G and the web plate groove 312G, from slipping out to the outside (to the right in Figure 11(b)), the height dimension of the contact plate 331 is made larger (wider) than the width dimension of the web plate groove 312G.

[0056] The connecting box bodies 100 are constructed for each unit tunnel 110, and the individual box bodies 200 are connected when two unit tunnels 110 are placed side by side. In other words, the individual box bodies 200 are not connected until a unit tunnel 110 is constructed in an adjacent location, and therefore the flange grooves 311G and web grooves 312G remain empty until then. In this case, when installing the individual box bodies 200 (or when moving the individual box bodies 200 in the tunnel axis direction in the case of the tunnel jacking method), there is a risk that soil and groundwater may enter the flange grooves 311G and web grooves 312G, and as a result, there is a risk that the joint material 320 may not be properly installed. Therefore, the individual box bodies 200 are installed with the opening cover material 330 housed in the flange grooves 311G and web grooves 312G, that is, with the gaps between the flange grooves 311G and web grooves 312G sealed by the opening cover material 330. This prevents soil and other debris from entering the flange groove 311G and web plate groove 312G, and by removing the opening cover material 330, the installation space for the joint material 320 is appropriately secured, which is preferable. For this reason, it is desirable that the opening cover material 330 be configured to be easily removed from the flange groove 311G and web plate groove 312G. For example, in the case of Figure 11, it is configured to be removed by sliding it in the tunnel axial direction.

[0057] 3. Connection box construction method Next, the method for constructing the connected box according to the present invention will be explained. The method for constructing the connected box according to the present invention is a method for constructing the connected box 100 using the box connecting structure 300 of the present invention described so far. Therefore, explanations that overlap with those described for the box connecting structure 300 will be avoided, and only the contents specific to the method for constructing the connected box according to the present invention will be explained. In other words, contents not described here are the same as those described in "2. Box Connecting Structure".

[0058] Figure 12 is a flowchart showing the main steps of the method for constructing a connected box structure according to the present invention. As shown in this figure, in constructing the connected box structure 100, first the underground launch section (e.g., launch shaft) and the underground arrival section (e.g., arrival shaft) are constructed (Step 501 in Figure 12). In addition, other planned temporary facilities and equipment are installed, and then the first unit tunnel 110 is constructed (Step 502 in Figure 12). The procedure for constructing the unit tunnel 110 will be described below. Note that the excavation of the unit tunnel 110 can be carried out by the pipe jacking method, the shield tunneling method, or other conventional methods, but for convenience, the example of excavation by the pipe jacking method will be described here.

[0059] To construct a unit tunnel 110, a thrusting device is first installed in the underground launching section. Then, the ground is excavated by the thruster lowered into the underground launching section. However, since the individual box bodies 200 that make up the connected box bodies 100 are roughly rectangular in cross-section, it is preferable to use a thruster designed for rectangular cross-sections (rectangular thruster). As the thruster excavates the ground, the thrusting device simultaneously pushes the individual box bodies 200 in the face direction (tunnel axis direction). At this time, it is preferable to push the individual box bodies 200 with the opening cover material 330 housed in the flange groove 311G and web plate groove 312G. The individual box bodies 200 are installed so as to be aligned in the tunnel axis direction from the tunnel entrance (underground launching section) side of the thruster, and as excavation progresses, individual box bodies 200 are supplied from the underground launching section while the thrusting device pushes the entire individual box body 200. In this way, a unit tunnel 110 is constructed by repeatedly performing "ground excavation ~ thrusting of individual box casings 200" until the thrusting machine reaches the underground section.

[0060] Once the first unit tunnel 110 is constructed, subsequent unit tunnels 110 are constructed in adjacent locations. Specifically, as described above, the ground is excavated using a thruster (rectangular thruster) (Step 503 in Figure 12), and the individual box bodies 200 are moved towards the tunnel face using thrust equipment (Step 504 in Figure 12). At this time, it is preferable to move the individual box bodies 200 with the opening cover material 330 housed in the flange groove 311G and web plate groove 312G. This series of processes (excavation of the ground ~ thrusting of the individual box bodies 200) is repeated until the thruster reaches the underground section, thereby constructing subsequent unit tunnels 110 (Step 505 in Figure 12).

[0061] When the subsequent unit tunnel 110 is constructed, that is, when the preceding unit tunnel 110 and the subsequent unit tunnel 110 are placed side by side, a section of natural ground (hereinafter referred to as the "connection section") remains between the two unit tunnels 110, as shown in Figure 13. Ultimately, concrete will be filled into this connection section as well, so it is necessary to excavate the connection section. However, in order to ensure the safety of those performing the excavation work and to prevent water leakage, the surrounding ground is improved (Step 506 in Figure 12). For example, in Figure 13, the ground is improved by injecting chemicals into the upper and lower parts of the connection section.

[0062] When ground improvement is performed at the connection point, the skin plate 220 is removed from the opening side of the individual box casing 200. At this time, as shown in Figure 14, only the skin plate 220 of the wall facing the individual box casing 200 is removed. For example, if two individual box casings 200 are adjacent to each other left and right, the skin plate 220 of the right wall of the left individual box casing 200L is removed, and the skin plate 220 of the left wall of the right individual box casing 200R is removed. Once the predetermined skin plates 220 are removed, the ground at the connection point is excavated from the opening side (Step 507 in Figure 12).

[0063] When the ground at the connection point is excavated, the opening cover material 330 housed in the flange groove 311G and web plate groove 312G are removed from each adjacent individual box body 200, and the joint material 320 is installed in the now-empty flange groove 311G and web plate groove 312G (Step 508 in Figure 12). More specifically, as previously described, the two adjacent individual box bodies 200 are connected by inserting the two flanges 322 into the flange groove 311G and inserting a portion of the web plate 321 into the web plate groove 312G. The joint material 320 is installed for each individual box body 200, that is, it is installed throughout the entire unit tunnel 110. Therefore, it is advisable to install a towing device such as a winch at the underground launching or underground arrival point and use this towing device to install the joint material 320. Specifically, a traction device installed at the underground launching section (or underground arrival section) pulls the joint material 320, causing it to move along the tunnel axis direction through the flange groove 311G and web plate groove 312G, and be installed sequentially at predetermined positions. The opening cover material 330 can also be removed using the traction device in the same manner as the joint material 320.

[0064] On the other hand, in the case where the joint support member 312 is provided with a notch 313, the joint material 320 is inserted through the notch 313 as described above. More specifically, as shown in Figure 10(a), the joint material 320 is placed into the notch 313 from below, and with a part of the web plate 321 inserted into the web plate groove 312G, the joint material 320 is slid in the tunnel axial direction to position it in the predetermined location, i.e., where the flange groove 311G is installed. In this case, it is preferable because it avoids the need to slide the joint material 320 in the tunnel axial direction using a winch or the like.

[0065] Once the joint material 320 is installed, cement-based filler (for example, high-strength mortar or concrete) is filled into the four corners (Step 509 in Figure 12). At this time, it is advisable to use the corner formwork 400 shown in Figure 15. This corner formwork 400 is made of plate-like members and is formed in an L-shape with a roughly right-angle cross-section. It can be manufactured, for example, by processing steel plates or using angle steel. As shown in Figure 15, when the corner formwork 400 is installed so as to cover the corner girder plates 311 that are positioned at the installation locations of the central main girder 211 and the side main girder 212, a space is formed between the corner formwork 400 and the corner girder plates 311, in which part of the joint material 320 is placed. Then, high-strength mortar is filled into this space. When filling with high-strength mortar, it is advisable to use the injection holes provided in the corner formwork 400. Alternatively, instead of the corner formwork 400 shown in Figure 15, the tube formwork described in "Japanese Patent Publication No. 3554698" can be used. This tube formwork expands to a predetermined shape by injecting water or air, and functions particularly effectively as formwork for narrow and complex areas. Furthermore, after use, the entire tube formwork can be wound up simply by pulling the wire installed inside, making it a formwork with excellent workability.

[0066] By performing the series of steps described so far (Steps 503 to 509 in Figure 12), the preceding unit tunnel 110 and the subsequent unit tunnel 110 are connected, and by repeating this series of steps, a connecting box body 100, such as the one shown in Figure 1, is constructed (Step 510 in Figure 12). At this stage, the openings of the individual box bodies 200 that make up the connecting box body 100 remain hollow, and the connecting box body 100 is, so to speak, an "outer shell". Depending on the design conditions, this outer shell can be considered the completed form of the connecting box body 100, but usually concrete is filled into the openings of the individual box bodies 200 and into the connections between adjacent individual box bodies 200. In this case, first the necessary reinforcing bars (e.g., shear reinforcement bars) are placed (Step 511 in Figure 12), and then concrete with a predetermined strength (e.g., high-strength concrete) is filled into the openings and connections (Step 512 in Figure 12).

[0067] Once the filled concrete has hardened sufficiently, the concrete connecting box 100 is completed (Step 513 in Figure 12), and by excavating the inside of the connecting box 100 (Step 514 in Figure 12), the underground space US is formed (Step 515 in Figure 12). [Industrial applicability]

[0068] The connected box structure and method for constructing the connected box structure of the present invention can be used in the construction of underground shopping malls and subway stations, as well as road tunnels, railway tunnels, water and sewage tunnels, utility tunnels, and power and telecommunications tunnels. Considering that the present invention enables the efficient construction of tunnel structures, which are social infrastructure, it can be said that this invention is not only industrially applicable but also has the potential to make a significant contribution to society. [Explanation of Symbols]

[0069] 100 connected box 110 Unit tunnel (of a connecting box structure) 200 Individual boxes (of connected boxes) 200L (Left individual box of individual boxes) 200R (Among the individual boxes) Right individual box 210 (Main girder of individual box) 211 (Central main girder of the main girders) 212 Side main girder (of the main girder) 220 (Individual box) skin plates 300 Box-connecting structure of the present invention 310 Corner body (of box-shaped connecting structure) 311 Corner main beam plate (of a corner body) 311G Flange groove (of corner main girder plate) 312 (Corner joint support) 312B Lower support member (of the joint support member) 312G (Glug groove of joint support) 312T Upper support member (of the joint support member) 313 Notch (of a corner body) 320 (Joint material for box-type connecting structure) 321 (Joint material) web plate 322 (Flange of fitting material) 330 (Opening cover material for connecting box) 331 (For opening cover material) contact plate 332 (Projection of opening cover material) 400 Corner formwork LB Long Bolt LN lining PB box SP space US underground space

Claims

1. In a connected box structure, which is formed by linking two or more individual boxes constructed underground, the structure connects adjacent individual boxes together. A connecting material that connects adjacent preceding individual box bodies and subsequent individual box bodies, The corner body provided at the corner of the preceding individual box and the succeeding individual box, It comprises an opening cover material consisting of a contact plate and a projection, The preceding individual box and the succeeding individual box, which have a rectangular or substantially rectangular cross-section, have an opening in the center when viewed in cross-section, and have main girders arranged around the opening. The aforementioned joint material has an H-shape in cross-section, consisting of a web plate and flanges positioned at both ends of the web plate. The aforementioned corner body consists of a corner main girder plate with a flange groove and a joint support member with a web groove. The contact plate is wider than the web plate groove, and the projection attached to the contact plate is narrower than the web plate groove. The projection is insertable into the flange groove and the web plate groove, and the opening cover material is removable from the flange groove and the web plate groove. The flanges are inserted into the flange grooves of the adjacent preceding individual box and the succeeding individual box, and a portion of the web plate is inserted into the web plate grooves of the preceding individual box and the succeeding individual box, thereby connecting the preceding individual box and the succeeding individual box by the joint material. The joint material is installed in the flange groove and the web plate groove from which the opening cover material has been removed. A box-type connecting structure characterized by the following features.

2. In a connected box structure, which is formed by linking two or more individual boxes constructed underground, the structure connects adjacent individual boxes together. A connecting material that connects adjacent preceding individual box bodies and subsequent individual box bodies, The system comprises the preceding individual box and the corner body provided at the corner of the succeeding individual box, The preceding individual box and the succeeding individual box, which have a rectangular or substantially rectangular cross-section, have an opening in the center when viewed in cross-section, and have main girders arranged around the opening. The aforementioned corner body consists of a corner main girder plate with a flange groove and a joint support member with a web groove. By cutting a portion of the aforementioned joint support member in the direction of the tunnel axis, a notch is formed in the joint support member. The corner main girder plate is positioned in a location where the notch is not provided. The aforementioned joint material has an H-shaped cross-section, consisting of a web plate and flanges positioned at both ends of the web plate, and its tunnel axial length is shorter than the tunnel axial length of the notch. The flanges are inserted into the flange grooves of the adjacent preceding individual box and the succeeding individual box, and a portion of the web plate is inserted into the web plate grooves of the preceding individual box and the succeeding individual box, thereby connecting the preceding individual box and the succeeding individual box by the joint material. A box-type connecting structure characterized by the following features.

3. The main girder includes side main girders positioned forward and backward in the tunnel axis direction, and a central main girder positioned between the forward and rear side main girders. The aforementioned notch is formed between the central main girder and the side main girder, The corner main girder plate is positioned at the location of the central main girder and also at the location of the side main girder. The box-type connecting structure according to feature 2.

4. The main girder includes side main girders positioned forward and backward in the tunnel axis direction, and a central main girder positioned between the forward and rear side main girders. The corner main girder plate is positioned at the location of the central main girder and also at the location of the side main girder. The box-type connecting structure according to claim 1 or 2.

5. The web plate groove of the aforementioned joint support member has a tapered shape that widens outward in cross-sectional view. The box-type connecting structure according to claim 1 or 2.

6. The flange of the aforementioned joint material has a tapered shape, becoming narrower towards the tip. The box-type connecting structure according to claim 5.

7. A method for constructing a connected box structure underground, which consists of two or more individual boxes connected together, The process involves installing pre-installed individual box structures while excavating the ground, and The process of installing subsequent individual box structures involves excavating the ground while installing subsequent individual box structures adjacent to the preceding individual box structures, The process includes a connecting step of connecting adjacent preceding individual box bodies and succeeding individual box bodies with joint materials and corner bodies, The preceding individual box and the succeeding individual box, which have a rectangular or substantially rectangular cross-section, have an opening in the center when viewed in cross-section, and have main girders arranged around the opening. The aforementioned joint material has an H-shape in cross-section, consisting of a web plate and flanges positioned at both ends of the web plate. The corner body is provided at the corner of the preceding individual box body and the succeeding individual box body and consists of a corner main girder plate with a flange groove and a joint support member with a web groove. In the preceding step of installing the individual box, the preceding individual box is installed with the contact plate, which is wider than the flange groove, and the opening cover material, which is attached between the contact plate and is narrower than the flange groove, installed in the flange groove and the web plate groove. In the subsequent individual box installation step, the subsequent individual box is installed with the opening cover material installed in the flange groove and the web plate groove. In the aforementioned coupling process, after removing the opening cover material from the flange groove and the web plate groove, the flange is inserted into the flange groove of the preceding individual box and the succeeding individual box, and a portion of the web plate is inserted into the web plate groove of the preceding individual box and the succeeding individual box, The opening cover material is installed in the flange groove and the web plate groove by inserting the projection into the flange groove and the web plate groove, The opening cover material is removed from the flange groove and the web plate groove by removing the projection from the flange groove and the web plate groove. A method for constructing a connected box, characterized by the features described herein.

8. A method for constructing a connected box structure underground, which consists of two or more individual boxes connected together, The process involves installing pre-installed individual box structures while excavating the ground, and The process of installing subsequent individual box structures involves excavating the ground while installing subsequent individual box structures adjacent to the preceding individual box structures, A connecting step in which adjacent preceding individual box bodies and succeeding individual box bodies are connected by joint materials and corner bodies, Corner formwork installation process, A filling process is included, The preceding individual box and the succeeding individual box, which have a rectangular or substantially rectangular cross-section, have an opening in the center when viewed in cross-section, and have main girders arranged around the opening. The main girder includes side main girders positioned forward and backward in the tunnel axis direction, and a central main girder positioned between the forward and rear side main girders. The aforementioned joint material has an H-shape in cross-section, consisting of a web plate and flanges positioned at both ends of the web plate. The corner body is provided at the corner of the preceding individual box body and the succeeding individual box body and consists of a corner main girder plate with a flange groove and a joint support member with a web groove. The corner main girder plate is positioned at the location of the central main girder and also at the location of the side main girder. In the aforementioned coupling process, the flange is inserted into the flange groove of the preceding individual box and the succeeding individual box, and a portion of the web plate is inserted into the web plate groove of the preceding individual box and the succeeding individual box, In the corner formwork installation process, the corner formwork is installed so as to cover the corner main girder plate. In the filling step, a filling material is filled into the space enclosed by the corner formwork and the corner main girder plate, where a portion of the joint material is placed. A method for constructing a connected box, characterized by the features described herein.

9. A method for constructing a connected box structure underground, which consists of two or more individual boxes connected together, The process involves installing pre-installed individual box structures while excavating the ground, and The process of installing subsequent individual box structures involves excavating the ground while installing subsequent individual box structures adjacent to the preceding individual box structures, The process includes a connecting step of connecting adjacent preceding individual box bodies and succeeding individual box bodies with joint materials and corner bodies, The preceding individual box and the succeeding individual box, which have a rectangular or substantially rectangular cross-section, have an opening in the center when viewed in cross-section, and have main girders arranged around the opening. The aforementioned joint material has an H-shape in cross-section, consisting of a web plate and flanges positioned at both ends of the web plate. The corner body is provided at the corner of the preceding individual box body and the succeeding individual box body and consists of a corner main girder plate with a flange groove and a joint support member with a web groove. A notch is provided in a part of the aforementioned joint support member, where the joint support member is cut out in the direction of the tunnel axis. The corner main girder plate is positioned in a location where the notch is not provided. In the aforementioned coupling process, the flange is inserted into the flange groove of the preceding individual box and the succeeding individual box, and a portion of the web plate is inserted into the web plate groove of the preceding individual box and the succeeding individual box, Furthermore, in the connection process, the joint material, whose axial length in the tunnel is shorter than the notch, is inserted from the notch, the web plate is inserted into the web plate groove, and the flange is inserted into the flange groove. A method for constructing a connected box, characterized by the features described herein.

10. In the aforementioned coupling process, the coupling material is pulled by a traction device installed in the underground launching section or underground arrival section while traveling along the flange groove and the web plate groove in the tunnel axial direction. A method for constructing a connected box according to claim 7 or 8, characterized in that it is a method for constructing a connected box.

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