Segment and buried structure

Abstract

To provide segments and buried structures that do not crack during excavation, have outer layer members with excellent machinability, are more inexpensive and environmentally friendly than resin composite materials, and contribute to a decarbonized society.SOLUTION: A segment constitutes a buried structure buried underground, forms the exterior of the buried structure, and comprises an outer layer part made of wood and a metal reinforcement member attached along an inner surface of the outer layer part.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a segment that forms a buried structure buried underground, and the buried structure. [Background technology]

[0002] The Urban Ring Method (registered trademark) is a conventionally known method for press-in construction of earth-retaining structures to build vertical underground structures. The Urban Ring Method is as follows: Earth-retaining panels are assembled into a ring-shaped structure at the installation site, and the ring-shaped structure is pressed into the ground using a press-in device. After the ring-shaped structure is pressed into the ground, the inside of the ring-shaped structure is excavated and soil is removed, and a new ring-shaped structure is added on top of it. This work process is repeated up to a specified depth. In this way, an underground structure such as a shaft is constructed.

[0003] Another known tunnel construction method is the shield tunneling method. The shield tunneling method is as follows: Each time a tunneling machine installed in a vertical shaft excavates a certain distance, a segment ring is constructed at the rear by assembling, for example, arc-shaped segments (segment pieces) into a ring shape. This is then sequentially extended to form a cylindrical lining, thereby constructing a shield tunnel.

[0004] Furthermore, a technique is known in which, after a buried underground structure is constructed, a lateral tunnel branching off in a direction different from the axial direction of the buried structure is constructed using a shield machine or the like. In this case, the segments in the portion of the buried structure that is excavated by the shield machine have a different configuration from the segments in the portion that is not excavated. Patent Document 1 discloses a segment in the excavated portion that has an outer layer member made of an excavable resin composite material and a metal reinforcing member covering the inner surface of the outer layer member. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-225929 Summary of the Invention [Problem to be solved by the invention]

[0006] The segments described in Patent Document 1 require the excavation of an outer layer member made of a resin composite material when excavating a branched adit after the construction of the buried structure. However, in Patent Document 1, because the outer layer member is made of a resin composite material, there is a risk of cracks occurring in the resin part. In addition, the cutter bits installed on the cutter head of the shield machine are subject to significant wear. Furthermore, because resin members are expensive and made from fossil fuels, they can be said to be counter to the creation of a decarbonized society from the perspective of the SDGs.

[0007] The present invention has been made to solve the above-mentioned problems, and provides segments and buried structures that do not crack during excavation, have outer layer components with excellent machinability, are cheaper and more environmentally friendly than resin composites, and contribute to a decarbonized society. [Means for solving the problem]

[0008] The segment of the present invention is a segment that constitutes a buried structure that is buried in the ground, and comprises an outer layer portion made of wood that constitutes the outside of the buried structure, and a metal reinforcing member that is attached along the inner surface of the outer layer portion. [Effects of the Invention]

[0009] According to the present invention, the outer layer is made of wood. This makes it easy to cut with a shield machine. It also helps prevent cracks from occurring during excavation. Utilizing wood as a "recyclable resource" contributes significantly to the SDGs. Furthermore, it is cheaper and more environmentally friendly than resin composites, and can contribute to a decarbonized society through measures such as the Promotion of Wooden Construction in Cities. [Brief explanation of the drawings]

[0010] [Figure 1]1 is a side view showing a buried structure according to a first embodiment. [Figure 2] 1 is a side cross-sectional view showing a buried structure according to a first embodiment. [Figure 3] FIG. 2 is a top cross-sectional view showing a normal segment according to the first embodiment. [Figure 4] FIG. 2 is a top cross-sectional view showing a segment according to the first embodiment. [Figure 5] FIG. 3 is an enlarged view showing a part of a segment according to the first embodiment. [Figure 6] 4A to 4D are four-view diagrams showing a segment located at an upper end according to the first embodiment. [Figure 7] 4A to 4D are four-view diagrams showing a segment located at the bottom end according to the first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the segment and buried structure according to the present invention will be described with reference to the drawings. Note that the present disclosure is not limited to the embodiments described below. In addition, in the following drawings, including FIG. 1, the size relationships between the components or parts may differ from the actual size relationships. In the following description, terms indicating directions are used as appropriate to facilitate understanding, but these terms are for explanatory purposes and do not limit the present disclosure. Examples of terms indicating directions include "up," "down," "right," "left," "front," and "rear."

[0012] Embodiment 1 [Buried structure 1] The buried structure 1 is also called a submerged structure, and is installed at the excavation start point, midpoint, or destination point of a tunnel constructed underground by a shield tunneling method or the like. The space inside the buried structure 1 serves as a transport route or ventilation opening for the shield machine.

[0013] FIG. 1 is a side view showing a buried structure 1 according to a first embodiment. As shown in FIG. 1, the buried structure 1 is formed in a circular shape when viewed from above. The buried structure 1 includes a sinking body 2, a base plate (not shown), and a sinking anchor (not shown). Note that the buried structure 1 is not limited to a circular shape when viewed from above, and may have other shapes such as a rectangle, an ellipse, or an oval.

[0014] [Sinking body 2] The sinking body 2 is constructed by stacking ring bodies 3 along the vertical direction. The portion of the sinking body 2 corresponding to the start point, midpoint, or destination of the adit excavation is formed as the excavation section D. The ring body 3 is formed by connecting multiple regular segments 10 in the width direction (circumferential direction) to form an annular body. The cutting edge ring 4 is a ring located at the bottom end of the sinking body 2, and its tip is tapered for ground penetration. The guide ring 5 is a ring located above the cutting edge ring 4, and is equipped with an inner guide that prevents interference with the excavator and guides the excavator near the cutting edge. During excavation, the clamshell bucket prevents interference with the regular segments 10 and the inner wall surfaces of the cutting edge ring 4 while excavating the specified vertical shaft.

[0015] FIG. 2 is a side cross-sectional view showing the buried structure 1 according to the first embodiment. FIG. 2 is a cross-sectional view taken along line AA in the height direction of FIG. 1. As shown in FIG. 2, the buried structure 1 has normal segments 10 and segments 20. The normal segments 10 constitute the majority of the buried structure 1, and the segments 20 constitute the portion corresponding to the excavated portion D. In the first embodiment, a case in which three segments 20 are joined in the height direction is illustrated, but the number of segments 20 is not limited. Furthermore, the width direction (circumferential direction) of the segments 20 is formed to be larger than that of the excavated portion D. Furthermore, in the first embodiment, the segments provided in the portions other than the excavated portion D are referred to as normal segments 10 to distinguish them from the segments 20 provided in the portion corresponding to the excavated portion D.

[0016] [Normal segment 10] FIG. 3 is a top cross-sectional view showing a normal segment 10 according to the first embodiment. FIG. 3 is a cross-sectional view taken along the line B-B in the width direction of FIG. 1. FIG. 3 illustrates a normal segment 10 joined to a segment 20 consisting of an outer layer 30 and a metal reinforcing member 40. The normal segment 10 is an earth-retaining panel constituting part of a buried structure 1. The buried structure 1 is used, for example, in a vertical shaft for constructing a foundation for a structure, a sewer system, a drainage well, or the like. The buried structure 1 is formed, for example, by stacking a plurality of normal segments 10 arranged in parallel around the circumferential direction of the vertical shaft in multiple layers along the depth direction of the vertical shaft. As shown in FIG. 3, the normal segment 10 includes a normal skin plate 11, a normal upper main girder 12, a normal lower main girder 13, a normal longitudinal rib 14, and a pair of normal joint plates 15. 3 is a cross-sectional view taken along the line B-B in the width direction of FIG. 1, so the normal-use lower main girder 13 and the lower bolt holes 13a are not shown, but the normal-use upper main girder 12 and the upper bolt holes 12a are also shown because the structure is the same even if the structure is turned upside down. Note that the normal segments 10 used to join the normal segments 10 have joining bolt holes formed at predetermined intervals near the width-direction centers of the normal-use upper main girder 12 and the normal-use lower main girder 13. In addition, in the explanation, the normal-use upper main girder 12 and the normal-use lower main girder 13 are distinguished from each other, but the normal segments 10 are used in vertical shafts, and it is possible for the normal-use upper main girder 12 to be used on the lower side, and the normal-use lower main girder 13 to be used on the upper side.

[0017] The normal use skin plate 11, normal use upper main girder 12, normal use lower main girder 13, and a pair of normal use joint plates 15 are all formed from steel plates. The normal use skin plate 11 is formed, for example, in the shape of a fan-shaped flat plate. The normal use upper main girder 12 is formed along the upper edge of the normal use skin plate 11. The normal use lower main girder 13 is formed along the lower edge of the normal use skin plate 11. One normal use joint plate 15 is formed along one side edge of the normal use skin plate 11. The other normal use joint plate 15 is formed along the other side edge of the normal use skin plate 11.

[0018] The normal segment 10 is formed in a concave shape with an opening on one side and is made up of a normal skin plate 11, a normal upper main girder 12, a normal lower main girder 13, a normal vertical rib 14, and a pair of normal joint plates 15. The normal skin plate 11 is arranged on the natural ground side (the side wall side of the shaft). The normal upper main girder 12 forms the upper surface of the normal segment 10. The normal lower main girder 13 forms the lower surface of the normal segment 10.

[0019] The normal use longitudinal ribs 14 are strength members provided between the normal use upper main girder 12 and the normal use lower main girder 13, and are structured to withstand press-fitting so as to maintain the shape of the normal segment 10 during manufacturing, transportation, and construction. The normal use longitudinal ribs 14 are formed into plate shapes using steel plates or the like. The shape and number of normal use longitudinal ribs 14 to be installed are determined, for example, taking into consideration the size and shape of the normal segment 10. A pair of normal use joint plates 15 form the side surfaces of the normal segment 10. The normal use upper main girder 12, normal use lower main girder 13, normal use longitudinal ribs 14, and the pair of normal use joint plates 15 are each joined to the normal use skin plate 11 by welding.

[0020] The normal-use upper main girder 12 has a plurality of upper bolt holes 12a formed therein. The normal-use lower main girder 13 has a plurality of lower bolt holes 13a formed therein. Bolts 17 (see Figure 5) are inserted into the upper bolt holes 12a and the lower bolt holes 13a when connecting normal segments 10 arranged in parallel in the vertical direction. When connecting normal segments 10 in the axial direction (shaft direction), bolts 17 are inserted into bolt holes formed at a predetermined interval near the widthwise center of the normal-use upper main girder 12 and the normal-use lower main girder 13. The upper bolt holes 12a and the lower bolt holes 13a are also used when connecting normal segments 10 and segments 20.

[0021] In the first embodiment, the upper bolt hole 12a and the lower bolt hole 13a are through holes with a circular cross section. That is, no female threads are formed on the inner peripheral surfaces of the upper bolt hole 12a and the lower bolt hole 13a. However, female threads may be formed on the inner peripheral surfaces of the upper bolt hole 12a and the lower bolt hole 13a. A plurality of bolt holes 16 are formed in each of the pair of normal joint plates 15. The plurality of bolt holes 16 are used to connect normal segments 10 arranged side by side in the left-right direction to form, for example, a ring-shaped structure.

[0022] The means for connecting the normal segments 10 together is not limited to bolts and nuts, but may be, for example, connectors such as clips. The numbers of upper bolt holes 12a and lower bolt holes 13a shown in the figure are merely an example, and are not intended to be limiting.

[0023] [Segment 20] Fig. 4 is a top cross-sectional view showing a segment 20 according to embodiment 1. Fig. 4 is a CC cross-sectional view in the width direction of Fig. 1. As shown in Fig. 4, segment 20 includes an outer layer portion 30 and a metal reinforcing member 40. The outer layer portion 30 mainly bears loads such as soil and water pressure, and the metal reinforcing member 40 mainly bears loads such as buoyancy when pressed in during construction.

[0024] [Outer layer 30] The outer layer 30 constitutes the exterior of the buried structure 1 and is made of wood. The outer layer 30 may be, for example, laminated timber (CLT) or CLT, which is a single board made by connecting multiple pieces of wood. Alternatively, the outer layer 30 may be formed by combining laminated timber and CLT. Either the laminated timber or the CLT may be placed on the skin plate 41 side. Alternatively, the CLT may be sandwiched between two pieces of laminated timber. The fibers of the laminated timber are unidirectional, while the fibers of the CLT are bidirectional. Because the fibers of the CLT are bidirectional, they can support loads in two directions. As shown in FIG. 2 , in this first embodiment, the outer layer 30 may include an outer layer 30 located at the upper end, an outer layer 30 located at the center, and an outer layer 30 located at the lower end. A bolt hole 31 is formed at the upper end of the upper outer layer 30 to connect it to the regular segment 10 located further above. Bolt holes 31 are formed, and nuts (not shown) or the like (not shown) are welded to the outer layer 30 of the main girder 42. Joining the normal segments 10 prevents misalignment between the normal segments 10 and 20, transmitting the load during press-fitting. Inserting a positioning member 33 into the positioning hole 32 achieves a similar effect (e.g., dowel joints). A sealing groove may be formed at the end of the outer layer 30. In this case, a waterproof sealant is applied during construction. The dowel joints described above may also be omitted. By digging a groove into the end face of one outer layer 30 and providing a protruding portion at the end of the other outer layer 30, and joining the groove and protrusion, the joining strength is improved compared to dowel joints, and waterproof performance is also improved (e.g., tongue and groove joints). Because the outer layer 30 is made of wood, the grooves and protrusions can be easily manufactured. In addition, if the outer layer 30 is made of CLT sandwiched between laminated timber, the CLT portion may be formed into a protrusion and recess. Alternatively, grooves may be formed in the end faces of the upper and lower outer layer portions 30, and plate-like members may be fitted into the upper and lower grooves. A positioning hole 32 is formed in the lower end of the outer layer portion 30 located at the upper end, into which a positioning member 33 is inserted to determine the position relative to the segment 20 located below.

[0025] Here, the characteristics of the outer layer 30 made of wood will be described. Each wooden structure has multiple plank-shaped wooden members, and the multiple wooden members are stacked in a direction from the outside to the inside of the buried structure 1. The outer layer 30 also has multiple wooden members, and the ends of the wooden members in the outer layer 30 abut against each other, with the abutting positions of the ends of adjacent layers being offset in the extension direction. Typically, the circumferential end positions of the segments 10 and 20 are offset (staggered). The circumferential end positions of the segments 20 may or may not be offset. The wooden outer layer 30 is made of, for example, laminated wood.

[0026] The wooden members can be freely glued and adjusted to any desired shape and length. Wooden members (laminated lumber) are treated with a flame-retardant coating (e.g., a flame-retardant coating) to prevent fires. Furthermore, large cross sections can be used to accommodate the wood's burning margin. In this case, if the surface scorches and a charred layer forms, the supply of oxygen to the interior is cut off, making it more difficult to burn. When the wooden members (laminated lumber) are buried underground, the outer layer 30 is in contact with the ground, so they are treated with a preservative (e.g., a dry preservative) to prevent decay. Furthermore, since they are not exposed to oxygen, one of the causes of decay, they do not decay underground. Each wooden member is made up of multiple wooden members, which are layered from the outside to the inside of the buried structure 1. The moisture content of the wooden members is approximately 28% or less, at which point drying shrinkage begins, and preferably approximately 15%, at which point they become stable in an air-dried state. Taking drying costs and other factors into consideration, a moisture content of approximately 20% is preferred.

[0027] Positioning holes 32 are formed at the upper and lower ends of the centrally located outer layer portion 30, through which positioning members 33 are inserted to determine the position of the segment 20 located above and the segment 20 located below. The end faces of the outer layer portions 30 of the centrally located segment 20 and the upper and lower segments 20 are in contact with each other. In addition to joining via the upper bolt holes 12a and the lower bolt holes 13a, inserting the positioning members 33 into the positioning holes 32 prevents the segments 20 from shifting position and transmits the load during press-fitting. The upper end of the lower-located outer layer portion 30 is formed with a positioning hole 32, through which the positioning members 33 are inserted to determine the position of the segment 20 above. The lower end of the lower-located outer layer portion 30 is formed with a bolt hole 31, through which the segment 20 is joined to the normal segment 10 located below. The formed bolt holes 31 are also used to join the segment 20 to the normal segment 10 located above.

[0028] [Metal reinforcement member 40] As shown in FIG. 4, the metal reinforcing member 40 is attached along the inner surface of the outer layer portion 30. The metal reinforcing member 40 includes a skin plate 41, an upper main girder 42, a lower main girder 42, a longitudinal rib 43, and a pair of joint plates 44. The skin plate 41, the upper main girder 42, the lower main girder 42, and the pair of joint plates 44 are all formed from steel plates. The skin plate 41 is formed, for example, in the shape of a fan-shaped flat plate. As shown in FIG. 2, the skin plate 41 abuts against the inner surface of the outer layer portion 30. Although not shown, the outer layer portion 30 and the skin plate 41 are joined at a predetermined interval by wood screws 45 (see FIG. 5). The size of the wood screws 45 can be changed as appropriate.

[0029] The upper main girder 42 is formed along the upper edge of the skin plate 41. The main girder 42 is formed in a fan-shaped flat plate shape. The lower main girder 42 is formed along the lower edge of the skin plate 41. The longitudinal ribs 43 are provided between the upper and lower main girders 42 to maintain the shape of the segment 20 during manufacturing, transportation, and installation. The longitudinal ribs 43 are components that withstand the load during press-fitting and also maintain the shape. The longitudinal ribs 43 are formed in a plate shape using steel plate or the like. The longitudinal ribs 43 are components that bear the press-fit force during installation, and their plate thickness, shape, installation location, number, etc. are appropriately designed depending on the size and installation scale of the segment 20. The shape and number of the longitudinal ribs 43 are determined, for example, taking into account the size and shape of the normal segment 10. One joint plate 44 is formed along one side edge of the skin plate 41. The other joint plate 44 is formed along the other side edge of the skin plate 41. The joint plate 44 is a flat plate-shaped member.

[0030] A plurality of upper bolt holes 12a are formed in the upper main girder 42. A plurality of lower bolt holes 13a are formed in the lower main girder 42. The upper bolt holes 12a and the lower bolt holes 13a are used to connect segments 20 arranged in parallel in the vertical direction. They are also used to connect regular segments 10 and 20. In this embodiment, the upper bolt holes 12a and the lower bolt holes 13a are through holes with a circular cross section. That is, no female threads are formed on the inner surfaces of the upper bolt holes 12a and the lower bolt holes 13a. However, female threads may be formed on the inner surfaces of the upper bolt holes 12a and the lower bolt holes 13a. A plurality of bolt holes 16 are formed in each of the pair of joint plates 44. The plurality of bolt holes 16 are used to connect regular segments 10 and 20 arranged in parallel in the left-right direction to form, for example, a ring-shaped structure.

[0031] The means for connecting segments 20 to each other or between a normal segment 10 and a segment 20 is not limited to bolts and nuts, but may be connectors such as clips. The numbers of upper bolt holes 12a and lower bolt holes 13a shown in the figure are merely examples and are not limited to these. The main girder 42 of the segment 20 at the joint between the normal segment 10 and the segment 20 has a width up to the outer layer 30 (the same width as the normal upper main girder 12 or normal lower main girder 13 of the normal segment 10), and the entire main girder 42 bears the load from above.

[0032] FIG. 5 is an enlarged view of a portion of the segment 20 according to the first embodiment. FIG. 5 is an enlarged view of the portion E surrounded by the dashed line in FIG. 4, i.e., an enlarged view of one widthwise end of the segment 20. As shown in FIG. 5, the widthwise end of the segment 20 is the portion that is normally connected to the segment 10. As described above, the outer layer portion 30 and the skin plate 41 are joined with wood screws 45. Alternatively, the outer layer portion 30 may be formed by sandwiching CLT between laminated timber, or the outer layer portion 30 formed of CLT and laminated timber may be connected at a predetermined interval by piercing the skin plate 41 and the outer layer portion 30 with a cuttable connector (such as a plastic bolt or nut). At one widthwise end of the segment 20, the outer layer portion 30 is attached between the skin plate 41 and a steel plate 46 joined to a normal joint plate 15. The steel plate 46 has a predetermined length in the circumferential direction and its axial length is the same as that of the skin plate 41. This reinforces the bonding strength between the outer layer portion 30 and the skin plate 41. Specifically, the steel plate 46 is attached so as to abut against the outer surface of the outer layer portion 30.

[0033] Then, reinforcing bolts 47, each having a length greater than the thickness of the outer layer portion 30, are inserted so as to penetrate the steel plate 46, the outer layer portion 30, and the skin plate 41, and are screwed into reinforcing nuts 48. Two sets of reinforcing bolts 47 and reinforcing nuts 48 are provided along the width direction. The number of bolts and nuts is not limited and can be changed as appropriate depending on the size of the excavation portion D, etc. This reinforces the joint strength between the outer layer portion 30 and the skin plate 41. The other end portion of the segment 20 in the width direction also has a configuration similar to that of the one end portion of the segment 20 in the width direction, and the joint strength between the outer layer portion 30 and the skin plate 41 is reinforced.

[0034] FIG. 6 is a four-view diagram showing the segment 20 located at the upper end according to the first embodiment. FIG. 6(a) is a front view, FIG. 6(b) is a side view, FIG. 6(c) is a top view, FIG. 6(d) is a bottom view, and FIG. 6(e) is a side cross-sectional view. As shown in FIG. 6, in the segment 20 located at the upper end, the main girder 42 located on the upper side extends to the outer surface of the outer layer portion 30. Therefore, as shown in FIG. 2, the main girder 42 located above the segment 20 located at the upper end abuts against the entire surface of the normal lower main girder 13 of the normal segment 10 located above. This ensures proper connection between the segment 20 located at the upper end and the normal segment 10 located above it.

[0035] FIG. 7 is a four-view diagram showing the segment 20 located at the lower end according to the first embodiment. FIG. 7(a) is a front view, FIG. 7(b) is a side view, FIG. 7(c) is a top view, FIG. 7(d) is a bottom view, and FIG. 7(e) is a side cross-sectional view. As shown in FIG. 7, in the segment 20 located at the lower end, the main girder 42 located on the lower side extends to the outer surface of the outer layer portion 30. Therefore, as shown in FIG. 2, the main girder 42 located below the segment 20 located at the lower end abuts against the entire surface of the normal lower main girder 13 of the normal segment 10 located below. This ensures proper connection between the segment 20 located at the lower end and the normal segment 10 located below it.

[0036] Here, when excavating a branched adit after constructing the buried structure 1, it is necessary to expose the wooden outer layer 30. Therefore, before excavating the adit, the metal reinforcing members 40 of the segments 20 are melted and cut off. As mentioned above, the wooden portion of the outer layer 30 is flame-retardant, so there is no risk of combustion. Furthermore, when wood is made large in cross section to allow for a burning margin, if the surface scorches and a carbonized layer forms, the supply of oxygen to the interior is cut off, making it difficult to burn. This exposes the wooden outer layer 30, allowing the adit to be excavated. Furthermore, a mark such as a notch may be made in advance on the skin plate 41 or the like at a position roughly corresponding to the excavation portion D. The presence of this notch mark facilitates the removal of the skin plate 41 from the segment 20.

[0037] As described above, the segment 20 of the first embodiment is a segment 20 constituting the buried structure 1 buried underground. The segment 20 forms the exterior of the buried structure 1 and includes a wooden outer layer 30 and a metal reinforcing member 40 attached along the inner surface of the outer layer 30. Thus, in the first embodiment, the outer layer 30 is made of wood. This facilitates cutting with a shield machine. Furthermore, the segment includes the outer layer 30, which bears loads such as soil and water pressure, and the metal reinforcing member 40, which bears loads during press-fitting and buoyancy. Furthermore, the use of CLT allows for the bearing of loads in two directions. Furthermore, the occurrence of cracks during excavation can be suppressed. Using wood as a "recyclable resource" significantly contributes to the SDGs. Furthermore, wood is cheaper and more environmentally friendly than resin composites, and can contribute to a decarbonized society through the Urban Wood Construction Promotion Act and other measures.

[0038] Various aspects of the present invention will be summarized below as appendices.

[0037] [Appendix 1] A segment constituting a buried structure buried underground, an outer layer portion made of wood that constitutes the outside of the buried structure; a metal reinforcing member attached along the inner surface of the outer layer portion; A segment comprising: [Appendix 2] The outer layer made of wood is Each of the wooden members has a plurality of plank-shaped wooden members, The plurality of wooden members include: Each is stacked in a direction from the outside to the inside of the buried structure. Segments as described in Appendix 1. [Appendix 3] The outer layer portion is A plurality of wooden members are included. Ends of the wooden members in the outer layer portion abut against each other, The contact positions of the ends of adjacent layers are shifted in the extension direction. A segment as described in Appendix 1 or 2. [Appendix 4] The wooden outer layer is made of laminated wood. A segment as set forth in any one of appendices 1 to 3. [Appendix 5] The laminated wood has: Flame retardant treated Segments as described in Appendix 4. [Appendix 6] The laminated wood has: It has been treated with antiseptic A segment as described in Appendix 4 or 5. [Appendix 7] The metal reinforcing member is a skin plate that abuts against the inner surface of the outer layer portion; A segment according to any one of appendices 1 to 6. [Appendix 8] The skin plate has Marks are provided in advance at positions corresponding to the excavated portions of the buried structure. Segments as described in Appendix 7. [Appendix 9] The mark is a notch Segments as described in Appendix 8. [Appendix 10] The metal reinforcing member is Has vertical ribs extending in the height direction A segment as set forth in any one of appendices 1 to 9. [Appendix 11] The metal reinforcing member is It has main beams extending in the width direction at the upper and lower ends. A segment according to any one of appendices 1 to 10. [Appendix 12] The main girder is extending to the outer surface of the outer layer portion Segment as described in Appendix 11. [Appendix 13] a joint plate provided at both ends in the width direction of the outer layer portion and the metal reinforcing member; A segment according to any one of appendices 1 to 12. [Appendix 14] The outer layer portion bears the load of soil and water pressure, The metal reinforcing member is used to bear the press-fitting force and buoyancy during construction. A segment according to any one of appendices 1 to 13. [Appendix 15] Segments described in any one of Supplementary Notes 1 to 14 A buried structure comprising: [Explanation of symbols]

[0039] 1 buried structure, 2 submerged body, 3 ring body, 4 cutting edge ring, 5 guide ring, 10 normal segment, 11 normal skin plate, 12 normal upper main girder, 12a upper bolt hole, 13 normal lower main girder, 13a lower bolt hole, 14 normal vertical rib, 15 normal joint plate, 16 bolt hole, 17 bolt, 20 segment, 30 outer layer, 31 bolt hole, 32 positioning hole, 33 positioning member, 40 metal reinforcing member, 41 skin plate, 42 main girder, 43 vertical rib, 44 joint plate, 45 wood screw, 46 steel plate, 47 reinforcing bolt, 48 reinforcing nut.

Claims

1. A segment constituting a buried structure buried underground, an outer layer portion made of wood that constitutes the outside of the buried structure; a metal reinforcing member attached along the inner surface of the outer layer portion; A segment comprising:

2. The outer layer made of wood is Each of the wooden members has a plurality of plank-shaped wooden members, The plurality of wooden members include: Each is stacked in a direction from the outside to the inside of the buried structure. The segment of claim 1 .

3. The outer layer portion is A plurality of wooden members are included. Ends of the wooden members in the outer layer portion abut against each other, The contact positions of the ends of adjacent layers are shifted in the extension direction. A segment according to claim 1 or 2.

4. The wooden outer layer is made of laminated wood. A segment according to claim 1 or 2.

5. The laminated wood has: Flame retardant treated The segment of claim 4.

6. The laminated wood has: It has been treated with antiseptic The segment of claim 4.

7. The metal reinforcing member is a skin plate that abuts against the inner surface of the outer layer portion; A segment according to claim 1 or 2.

8. The skin plate has A mark is provided in advance at a position corresponding to the excavated portion of the buried structure. The segment of claim 7.

9. The mark is a notch The segment of claim 8.

10. The metal reinforcing member is Has vertical ribs extending in the height direction A segment according to claim 1 or 2.

11. The metal reinforcing member is It has main beams extending in the width direction at the upper and lower ends. A segment according to claim 1 or 2.

12. The main girder is extending to the outer surface of the outer layer portion The segment of claim 11.

13. a joint plate provided at both ends in the width direction of the outer layer portion and the metal reinforcing member; A segment according to claim 1 or 2.

14. The outer layer portion bears the load of soil and water pressure, The metal reinforcing member is used to bear the press-fitting force and buoyancy during construction. A segment according to claim 1 or 2.

15. The segment according to claim 1 or 2. A buried structure comprising:

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