JP2009097305A - Extra-large precast box culvert and construction method of extra-large precast box culvert - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a precast block constituting an extra-large box culvert and its construction method reducing weight while enhancing strength to bending moment and shearing force and building up the precast culvert larger than conventional ones. <P>SOLUTION: A thinning recessed part 16 is formed in an intermediate part inside center portion of a top slab block 10 along the longitudinal direction of the top slab block 10. PC steel members 17 are embedded in both side parts of the top slab block 10. Both ends of the PC steel members 17 are engaged with locking means 24 at both ends of the top slab block 10 to stretch the PC steel members 17. The PC steel members 17 are located in reinforcing ribs 10d left on both sides of the thinning recessed part 16 at an intermediate part of the top slab block 10, inclined outward in the top slab block 10 toward both ends of the top slab block 10 from the intermediate part of the top slab block 10, and located outside the top slab block 10 at both ends of the top slab block 10. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention assembles reinforced concrete blocks precast at factories, etc. as culverts at construction sites, embeds them underground as substitutes for road tunnels and bridges, and precasts used for bridges, feed / drainage channels, etc. The present invention relates to a box culvert and a method for constructing a precast box culvert, and more particularly to a method for constructing a super-sized precast box culvert having a larger inner width than that of the conventional and a precast box culvert.

There are the following large-scale precast box culvert construction methods used for underground passages and tunnels at road intersections.
This technology consists of a top plate block and left and right side wall blocks made of precast concrete with reinforcing bars, and a bottom plate block or an in-situ bottom plate made of precast concrete. A cross-through for connecting a top plate block formed into a concave cross-section formed by piercing through PC steel material and penetrating through holes through which the vertical PC steel material is inserted through the front and rear surfaces, and a leg piece facing each other Tension PC which drills a through-hole through which PC steel material is inserted in the thick part of the leg piece, drills a through-hole which penetrates through the lower front and rear faces and inserts PC steel material, and connects to the top block A side wall block in which a concave portion is formed on an outer surface formed by embedding a steel rod is manufactured, and the top plate block and the side wall block are assembled in a frame shape, and the top plate block and the side wall are assembled. Insert the vertical PC steel material and the vertical PC steel material into the through hole of the lock and tighten it tightly, and the top plate block and the side wall block are tensioned with the PC steel material to form an assembly frame body. One is known that is aligned and tightened with an extended connection PC steel material and integrated as a culvert as a whole (see, for example, Patent Document 1).

In such Patent Document 1, although the top block and the side wall block are precast for each part, since these are concrete products, the weight is considerably increased, and the work at the time of transportation and construction is accompanied by considerable difficulty. Therefore, the meat stealing portion is provided outside the top plate block and the side wall block, and the meat stealing portion ensures the required strength while reducing the weight of the top plate block and the side wall block (FIGS. 1 to 1 of Patent Document 1). 4).
Japanese Patent No. 398345

When the precast box culvert shown in Patent Document 1 is buried in the soil, as shown in FIG. 13, the top plate block 3 and the left and right side wall blocks 4 and 4 and the bottom plate block constituting the assembly frame 2 of the box culvert 1 The bending moment M acts on 5.
For example, when the culvert 1 is applied to an underground passage under a three-dimensional intersection road, the bending moment M is applied to the top block 3 by the earth pressure, snow pressure, vehicle movement load, and the like as the bending moment M1, In addition, earth pressure or snow pressure from the lateral direction acts as a bending moment M2 on each of the side wall blocks 4 and 4, and further, on the bottom slab block 5 through the top slab block 3 and the side wall blocks 4 and 4, upward and lateral. The earth pressure, snow pressure, vehicle moving load, etc. from the direction act as the bending moment M3.

In particular, in the top block 3 where a large load from above is applied, the bending moment M1 acts on the inside at the middle portion and the bending moment M1 acts on the outside at both ends.
With respect to such a bending moment M1, the through PC steel material of Patent Document 1 applies a compressive stress due to a prestressing force in the longitudinal direction of the top plate block 3 inside the top plate block 3, and the top plate block 3 However, when the culvert 1 is used as an underground passage, tunnel, or waterway under a three-dimensional intersection road, the inner width W is 13 m. The degree was the limit.

For this reason, if an internal space width W of 13m or more is required, the precast blocks that make up the assembly frame can be made thick, or a double box with two culverts placed side by side. is doing.
Of these, the increase in the size of the precast block due to the increase in the thickness makes it difficult to increase the cost due to increased material costs, labor costs, and production costs, and makes it difficult to carry and construct.
In addition, the double box does not increase the size of each precast block, so there is no cost increase, transportation, or construction. However, the number of precast blocks is almost doubled compared to the single box, so the construction man-hours A significant increase in the construction period is inevitable. Moreover, a land for placing two side wall blocks between the two culverts has to be secured, resulting in a significant increase in costs.

  The present invention has been made in the background of such circumstances, and the object of the present invention is to reduce the weight of the precast block in which the bending moment and the shearing force are large while keeping the size of the precast block as before. The object is to provide an ultra-large precast box culvert having a larger inner space width and a method for constructing an ultra-large precast box culvert at a low cost by increasing the strength.

  In accordance with the above-described object, the super large box culvert of the present invention comprises a top plate block, left and right side wall blocks, a bottom plate block made of precast concrete, or a field-bottomed bottom plate, a vertical PC steel material and a horizontal PC steel material. In an ultra-large box culvert used to form an ultra-large box culvert by forming an assembly frame body by connecting them together, arranging a plurality of the assembly frame bodies in the horizontal direction and connecting them together with an extended connection PC steel material , A meat stealing recess is formed along the longitudinal direction of the top plate block in the middle portion inside the middle portion of the top plate block, PC steel is embedded in both sides of the top plate block, and both ends of the PC steel material are The PC steel material is stretched by being attached to both ends of the top plate block, and the PC steel material is left on both sides of the meat stealing recess at an intermediate portion of the top plate block. The top plate block is inclined outwardly from the middle portion of the top plate block toward the both end portions of the top plate block, and at both ends of the top plate block, the outside of the top plate block. It is characterized by being embedded in.

  In the super large box culvert of the present invention, an extension piece directed toward the side wall block is provided at both ends of the top plate block, and a haunch is provided at an inner corner of the extension piece and the top plate block. The length of the top plate block in the longitudinal direction of the haunch is set to be longer than the length in the inside and outside of the top plate block perpendicular thereto, and at the lower end of the side wall block, the leg protrudes in the bottom plate block or in-situ bottom plate direction Extending the piece, providing a haunch at the inner corner of the leg piece and the side wall block, the length of the top plate in the longitudinal direction of the top plate block is longer than the length in the inside and outside direction of the top plate block perpendicular thereto It can also be set.

  Also, the super large box culvert of the present invention has an extension piece projecting in the direction of the side wall block at both ends of the top block, and a meat stealing recess is formed in the longitudinal direction of the side wall block at the inner central portion of the side wall block. A PC steel stranded wire formed by twisting a plurality of PC steel wires is embedded as the longitudinal PC steel material on both inner side portions of the side wall block that is formed along the direction and sandwiches the meat stealing recess, and the longitudinal PC The steel material inclines the side wall block outwardly toward the extension piece connection side end direction and the lower end direction of the side wall block, respectively. It is located outside the block, and one end side of the longitudinal PC steel material is projected from the extension piece connection side end portion, and the top plate block is horizontally mounted on top of the both side wall blocks, and the extension Is inserted into the extension piece connection side end of the side wall block, one end side of the longitudinal PC steel material protruding from the extension piece connection side end portion is inserted, and one end portion of the longitudinal PC steel material is inserted into the extension piece A sheath means for connecting the top plate block and the both side wall blocks integrally with each other by attaching the vertical PC steel material to the outer end of the top plate block, and extending the side wall to the extension piece of the top plate block. It is provided penetrating in the longitudinal direction of the block, and either a guide hole or a guide pipe is used as the sheath means of the extension piece, and the entire sheath means is located at the extension piece connecting side end of the side wall block. You may arrange | position on the outer side of the extension piece corresponding to longitudinal PC steel material.

  Furthermore, in the super large box culvert of the present invention, a meat stealing recess is formed in the inner central portion of the bottom slab block along the longitudinal direction of the bottom slab block, and on both inner sides of the bottom slab block sandwiching the meat stealing recess. A sheath means using either a guide hole or a guide pipe is provided penetrating in the longitudinal direction of the bottom plate block, and when the bottom plate block is disposed between the leg pieces of the both side wall blocks, the sheath of the bottom plate block Continuously with the means, a PC steel stranded wire obtained by twisting a plurality of PC steel wires is inserted as the transverse PC steel material, and both ends of the transverse PC steel material are engaged with the outer end portions of both leg pieces. By extending PC steel, sheath means for integrally connecting the both side wall blocks and the bottom slab block are provided through both sides of the leg pieces of the side wall block in the longitudinal direction of the bottom slab block. Fragment Either a guide hole or a guide pipe is used as the sheath means, and the sheath means of the leg piece is in a position that matches the sheath means of the bottom plate block at the connection side end with the bottom plate block. The leg piece may be inclined outwardly from the position toward the outer end portion, and may be positioned outside the leg piece in the vicinity of the outer end portion of the leg piece.

  Further, in the precast box culvert construction method of the present invention, the top plate block and the left and right side wall blocks made of precast concrete, and the bottom plate block or on-site bottom plate made of precast concrete are connected to the longitudinal PC steel material and the horizontal. In a precast box culvert construction method in which an assembly frame body is configured by connecting with through PC steel materials, a plurality of the assembly frame bodies are arranged in a horizontal direction, and these are integrally connected with an extended connection PC steel material to constitute a box culvert. The top block is divided into an intermediate piece and two end pieces, and a meat stealing recess is formed along the longitudinal direction of the intermediate piece at the inner central portion of the intermediate piece, and the meat stealing recess Sheathed hand using either guide holes or guide pipes on both inner sides of the intermediate piece And a sheath means using either a guide hole or a guide pipe is provided through each of the end pieces in the longitudinal direction of the end piece. The sheath means of the part piece is in a position that matches the sheath means of the intermediate piece at the end of the intermediate piece connecting side, and the end piece is moved from the matching position toward the outer end of the end piece. Inclined outwardly and located outside the end piece in the vicinity of the outer end of the end piece, both end pieces are disposed at both ends of the intermediate piece, and the intermediate piece and the end A PC steel stranded wire in which a plurality of PC steel wires are twisted through these continuous sheath means is inserted as a PC steel material, and both ends of the PC steel material are connected to the outer ends of the end pieces. PC steel material By setting, it is characterized by integrally connecting with said intermediate portion piece and both end-piece as said top plate block.

  As a method for building a precast box culvert of the present invention, when producing the precast concrete for the intermediate piece, an auxiliary PC steel bar is embedded in the longitudinal direction of the intermediate piece, and the end of the auxiliary PC steel bar is set as an end. Exposed to the end of the piece connection side, and the end pieces are provided with sheath means using either guide holes or guide pipes in the longitudinal direction of the end pieces, respectively. When connecting the pieces, a separate auxiliary PC steel rod is inserted into the sheath means of the end piece, the auxiliary PC steel rod and the auxiliary PC steel rod of the intermediate piece are connected by a coupler, Both auxiliary PC steel materials can be stretched by engaging the end portion of the auxiliary PC steel rod inserted through the sheath means with the outer end portion of the end piece.

  Further, in the precast box culvert construction method of the present invention, when the end piece is manufactured in the precast concrete, the end piece and the extension piece from the outer end portion of the end piece toward the side wall block. At the corner, a haunch having a length in the longitudinal direction of the intermediate piece longer than the length in the inside / outside direction of the intermediate piece perpendicular to the intermediate piece is integrally formed, and when the side wall block is manufactured in precast concrete, The length of the top plate block in the longitudinal direction is longer than the length in the inside and outside of the top plate block at the inner corner of the bottom plate block or the leg piece projecting in the spot bottom plate direction from the lower end of the end block. A long haunch may be integrally formed.

  Further, as a method for building a precast box culvert of the present invention, when manufacturing the precast concrete for the side wall block, a meat stealing recess is formed along the longitudinal direction of the side wall block at the inner central portion of the side wall block, A PC steel stranded wire obtained by twisting a plurality of PC steel wires is embedded as the longitudinal PC steel material on both inner side portions of the side wall block sandwiching the theft recess, and the longitudinal PC steel material is an extension piece of the side wall block. The side wall block is inclined outwardly toward the connection side end direction and the lower end direction, and the side wall block is positioned outside the side wall block in the vicinity of the extension piece connection side end portion and the lower end portion, and vertically. When one end side of the PC steel material is protruded from the end of the extension piece connecting side, and the end piece is manufactured in precast concrete, the end piece A sheath means using either a guide hole or a guide pipe is provided in the extension piece from the outer end portion toward the side wall block in the longitudinal direction of the bottom plate block, and the entire sheath means of the extension piece is provided. The longitudinal PC steel material that is disposed outside the extension piece that matches the sheath means of the side wall block, has the end piece disposed on the side wall block, and protrudes from the end of the side wall block on the connection side of the extension piece By inserting one end side of each of the extension pieces into the sheath means of each extension piece, and engaging one end portion of the longitudinal PC steel material with the outer end portion of the end piece to stretch the longitudinal PC steel material. The block and the side wall blocks can be integrally connected.

  Further, in the precast box culvert construction method of the present invention, when manufacturing the precast concrete of the bottom block, a meat stealing recess is formed along the longitudinal direction of the bottom block in the inner central portion of the bottom block. Sheath means using either guide holes or guide pipes are provided in both sides of the bottom plate block across the stealing recess in the longitudinal direction of the bottom plate block, from the lower end of the side wall block to the bottom plate block direction. Sheath means using either a guide hole or a guide pipe is provided on both sides of the protruding leg piece so as to penetrate in the longitudinal direction of the bottom slab block, and the sheath means of the leg piece is connected to the bottom slab block. The leg piece is located at a position that coincides with the sheath means of the bottom block at the end, and proceeds from the coincident position toward the outer end of the leg piece. It is inclined outward and is located outside the side wall block in the vicinity of the outer end of the leg piece. The bottom block block is disposed between the leg pieces of the both side wall blocks, and the bottom block block and both legs are arranged. A piece of sheath means is made continuous, and a PC steel stranded wire obtained by twisting a plurality of PC steel wires through the continuous sheath means is inserted as the transverse PC steel material, and both ends of the transverse PC steel material are connected to both leg pieces. You may make it connect the said both-sides wall block and the said bottom slab block integrally by engaging with an outer end part and extending | stretching PC steel materials.

  PC steel material used for a single top plate block in the present invention, PC steel material used for a three-part top plate block, longitudinal PC steel material used for connection between a top plate block and a side wall block, connection between a side wall block and a bottom plate block The through PC steel material used for is a PC steel stranded wire in which a plurality of thin PC steel wires are twisted. In addition, in a three-part top plate block, the same one PC steel rod is used for reinforcement. Use.

  In the case of an integrated top plate block, a PC steel stranded wire is preliminarily embedded in concrete as a PC steel material when precast molding. After the concrete has dried and solidified, both ends of the PC steel are engaged with both ends of the block, and the PC steel is stretched without loosening by pulling the both ends of the PC steel, so that the PC steel has the required strength. To have. When the PC steel material is stretched, it is desirable that an unbonded PC steel stranded wire whose surface is coated with a lubricating film such as a polymer material is used for the PC steel material because the periphery is solidified by solidified concrete. .

Longitudinal PC steel material that connects the top plate block and the side wall block is also embedded in advance when the side wall block is precast, inserted into the sheath means of the extension piece in combination with the top plate block at the construction site, and then stretched by towing. In order to give the required strength by installing, unbonded PC steel strands may be used for the side wall blocks so that the tensile strength of the longitudinal PC steel material is not hindered by the solidified side wall block concrete.
In addition, in the case of the horizontal PC steel material, a guide hole or a guide pipe is provided as a sheath means in the bottom plate block or the side wall block, and when the bottom plate block and the side wall block are assembled on site, the guide hole or guide pipe of the sheath means is provided. After inserting the through PC steel material, the through PC steel material is stretched without loosening.

  PC steel material stretched in the internal longitudinal direction of the top plate block of an integral one, or PC steel material stretched in the internal longitudinal direction of the top plate block divided into three parts, the intermediate piece and the end pieces on both sides thereof Longitudinal PC steel stretched in the inner longitudinal direction of the leg pieces of the top plate block and the side wall block, Transverse PC steel material stretched in the inner longitudinal direction of the leg pieces of the bottom plate block and the side wall block, The part is located on the inner side (close to the inner space of the precast box culvert) and acts as a large drag against the bending moment acting inward, and the end of the PC steel is on the outer side (opposite the inner space of the precast box culvert) It is located and acts as a large drag force on the bending moment acting in the outward direction, ensuring a greater strength than the configuration of Patent Document 1 in each block.

In the connection of the top block divided into three parts, the intermediate piece and the end pieces on both sides, the PC steel strand is used as the PC steel, and the auxiliary PC steel rod is used in combination to increase the connection strength. it can.
In addition, as shown in FIG. 12, the bending surface which acts on the centerline L1 of the length direction which equally divides the thickness of a top plate block, and a top plate block from the division | segmentation surface of an intermediate | middle part piece and both-ends piece. When it is set on the intersections P1 and P1 with the moment M1, the bending moment M1 acting on the intersections P1 and P1 is substantially 0, and the connection strength by the PC steel is not so much required, so the PC steel stranded wire as the PC steel There is an advantage that the amount of use of can be reduced.
Further, it is preferable to form the dividing surface in a step shape so that the alignment can be easily performed and the strength can be ensured.

  In addition, a load from earth pressure, snow pressure, etc. acts as a shearing force on the leg pieces of the top plate block and the side wall block arranged in the horizontal direction. Since it increases toward the side wall block side of the piece, the haunch provided at the inner corner portion of the top plate block and the extension piece and the inner corner portion of the side wall block and the leg piece is elongated along the longitudinal direction of the top plate block. By setting the thickness, the thickness increases toward the end side of the top block and the side wall block side of the leg piece, so that sufficient strength as a drag force of the shearing force is secured.

  The sheath means is a hole drilled in the concrete or a pipe material embedded in the concrete when the top plate block, the side wall block and the bottom plate block are precast-molded, and these precast concrete blocks are integrated at the construction site. It facilitates the insertion of PC steel used for assembly.

  The precast box culvert of the present invention and the construction method thereof are precast concrete blocks such as a top block, and PC steel, transverse PC steel, and longitudinal PC steel are stretched with different phases inside and outside. It can secure greater strength than the conventional concrete block and can withstand bending moments and shear loads. As a result, it is possible to produce a super-sized precast box culvert with a large inner space width while the precast concrete block has a conventional size that is easy to transport and construct. Since it is not necessary to use a double box, it is possible to significantly reduce the construction man-hours and the construction period and to keep the production cost extremely low.

In addition, PC steel, horizontal PC steel, and vertical PC steel are inserted or stretched by using sheath means with guide holes or guide pipes to connect the three-part top block and each precast concrete block. Field work can be done very easily in a short time.
Furthermore, by setting the haunch provided at the inner corner of the top plate block and the extension piece and the inner corner of the side wall block and the leg piece long along the longitudinal direction of the top plate block, it is sufficient as a drag of the shearing force. Since sufficient strength is ensured, the precast box culvert can be further increased in size, or the meat stealing portion of the top plate block or the bottom plate block can be increased to further reduce the weight.

Embodiments of the present invention will be described below with reference to FIGS.
1 to 4 show a first embodiment of the present invention, FIG. 1 is a sectional front view of a super large box culvert, FIG. 2 is a perspective view of the super large box culvert, and FIG. FIG. 3B is a cross-sectional view of FIG. 3A, FIG. 4A is a side view of the same ultra-large box culvert, and FIG. 4 is a sectional view of FIG. 4A, FIG. 5 and FIG. 6 show a second embodiment of the present invention, FIG. 5 is a sectional front view of an ultra-large box culvert, and FIG. 7 is a cross-sectional front view of a super large box culvert showing a third embodiment of the present invention, FIGS. 8 to 12 show a fourth embodiment of the present invention, and FIG. 8 is a perspective view of the super large box culvert. 9 is a cross-sectional front view of an ultra-large box culvert, and FIG. 10A is a top block. Sectional front view, FIG. 10 (b) also a side view of Itadakiban block, 11 is a plan view of the top plate blocks, Figure 12 is an explanatory view of a bending moment acting on the top plate block.
In describing each embodiment of the present invention, reference is made to FIG. 13 used in the description of the prior art.

  In the first embodiment shown in FIGS. 1 to 4, the top plate block 10 is integrated, and the top plate block 10, the left and right side wall blocks 11, 11, and the bottom plate block 12 constitute an assembly frame 13, A plurality of the assembly frame bodies 13 are arranged in the lateral direction to constitute an ultra-large box culvert 14, and an internal space 15 serving as an underground passage or a tunnel is defined inside the culvert 14. The size and weight of each of the blocks 10 to 12 are substantially the same as in Patent Document 1, but the strength against external bending moment and shearing force is increased, and the inner space 15 has an inner space width W of about 13 to 18 m. We are trying to secure it.

Each of the top plate block 10, the side wall blocks 11, 11 and the bottom plate block 12 is manufactured in advance by a precast concrete containing a reinforcing bar at a factory or the like. It is formed in the downward U-shape which provided the extension pieces 10b and 10b which go to the side wall block 11 and 11 direction in the both ends of the main-body part 10a to be performed.
In the main body 10a of the top block 10, a meat stealing recess 16 is provided along the longitudinal direction of the main body 10a in the middle part of the middle part, and a pair of PC steel materials 17 and 17 are embedded on both sides thereof. Haunches 10c and 10c are provided at the inner corners of the main body 10a and the extension pieces 10b and 10b, and sheath means 18 and 18 using guide holes or guide pipes are provided in the vertical direction inside the extension pieces 10b and 10b. It is formed through.

Each side wall block 11 is formed in a substantially L shape integrally provided with a leg piece 11b protruding in the direction of the bottom block 12 at the lower end of the main body part 11a in the vertical direction, and the inner side of the main body part 11a and the leg piece 11b. Haunches 11c and 11c are provided at the corners, and a PC steel material 20a is embedded vertically in the vertical direction inside the main body 11a.
The body portion 11a of the side wall block 11 is provided with a meat stealing recess 21 in the middle portion inside the intermediate portion along the longitudinal direction of the body portion 11a, and sheath means 22 is provided on both sides of the leg piece 11b. Are provided penetrating in the longitudinal direction.

  The bottom plate block 12 is formed in a linear shape with a length so as to fill the space between the leg pieces 11b and 11b when the top plate block 10 is installed on the upper side of the side wall blocks 11 and 11 at the construction site. A meat stealing recess 23 is provided in the inner central portion along the longitudinal direction for the purpose of weight reduction, and sheath means 24 are provided through both sides of the bottom slab block 12 in the longitudinal direction.

The PC steel materials 17 and 17 provided in the top block 10 are linearly positioned in the reinforcing ribs 10d left on both sides of the meat stealing recess 16 at the intermediate portion of the main body portion 10a, and are intermediate portions of the main body portion 10a. The main body 10a is inclined outwardly from the top toward the end of the top block 10, and both ends of the main body 10a are embedded in a straight line outside the main body 10a.
As the PC steel members 17 and 17, unbonded PC steel stranded wires in which a surface of a PC steel stranded wire obtained by twisting a plurality of thin PC steel wires is coated with a lubricating film such as a polymer material are used. When the precast concrete is manufactured as described above, the unbonded PC steel stranded wire is embedded integrally in the concrete kneaded as the PC steel materials 17 and 17, and the concrete is hardened to a predetermined strength as the top plate block 10. Concrete in which locking means 24 such as washers and stoppers are attached to both ends of the PC steel material 17 projecting outward from both ends of the main body 10a, and the PC steel materials 17 and 17 are hardened by the locking means 24. The PC steel materials 17 and 17 are stretched without loosening.

  As a result, the top plate block 10 is greatly reduced in weight at the inside of the intermediate portion of the main body portion 10a by the meat stealing portion 16, but at the portion where the PC steel materials 17 and 17 are disposed, that is, at the central portion of the main body portion 10a. , A large strength is secured by the tension of the PC steel materials 17 and 17 at the inner portion (the portion near the inner space 15 in FIG. 1) where the bending moment M1 (see FIG. 13) acts greatly inward, and both ends of the main body portion 10a. Since the strength of the outer portion (upper portion of the main body portion 10a) where the bending moment M1 (see FIG. 13) acts greatly in the same direction is ensured by the PC steel materials 17 and 17, the top block 10 after construction It can withstand the bending moment M1 acting on the surface.

The longitudinal PC steel material 20a provided in the main body 11a of the side wall block 11 is an unbonded PC steel bar embedded when the side wall block 11 is precast-molded with concrete, and one end is a locking means on the lower surface of the leg piece. A coupler 26a is fixed to the other end of the main body 11a which is fixed to the other end of the main body 11a.
The sheath means 22 provided on the leg piece 11b of the side wall block 11 is a guide hole established when the side wall block 11 is precast-molded with concrete or a guide pipe embedded integrally in the concrete. Is located on the inner side (close to the inner space 15 in FIG. 1) of the leg piece 11b that matches the sheath means 24 of the bottom block 12, and from the matching position toward the outer end of the side wall block 11. The side wall block 11 is inclined outward as it goes, and in the vicinity of the outer end portion of the side wall block 11, outside the side wall block 11 (on the side opposite to the internal space 15 in FIG. 1), substantially parallel to the lower surface of the leg piece 11 b. positioned.

  The sheath means 24 provided on the bottom slab block 12 is a guide hole which is opened when the bottom slab block 12 is precast molded with concrete or a guide pipe embedded integrally in concrete, and sandwiches the meat stealing recess 23. The inner side (near the inner space 15 in FIG. 1) is located on both sides parallel to the upper surface of the bottom block 12.

  Each hunch 10c provided at the inner corner of the main body 10a and the extension piece 10b of the top block 10 and each hunch 11c provided at the inner corner of the main body 11a and the leg piece 11b of the side wall block 11 are respectively The length in the longitudinal direction of the top plate block (left and right direction in FIG. 1) is set to be longer than the length in the inside and outside direction of the top plate block (up and down direction in FIG. 1), and each of the hunches 10c and 11c It forms so that thickness may increase gradually as it goes to the side wall block side of the edge part side or the leg piece 11b.

The top block 10, the side wall blocks 11, 11 and the bottom block 12, which have been precast as described above, are transported to a construction site such as an underground passage, a tunnel, a waterway, a bridge, and the like. 12 is temporarily assembled into a frame shape.
By this temporary assembly, the longitudinal PC steel material 20b is inserted into the sheath means 18 of the top block 10 which is continuous with the longitudinal PC steel material 20a of the side wall block 11, and the coupler 26b of the longitudinal PC steel material 20b is longitudinally passed through the PC steel material 20a. Coupled with the coupler 26a, the locking means 27 at the end of the longitudinal PC steel material 20b is engaged with the upper surface of the top plate block 10, and the longitudinal PC steel materials 20a and 20b are straightened by retightening the locking means 27. The top plate block 10 and the side wall blocks 11 and 11 are connected to each other.

Further, by the above temporary assembly, the sheath means 22, 24, 22 of the side wall block 11, 11 and the bottom slab block 12 are continuous, and the PC steel material 28 is inserted through the sheath means 22, 24, 22 to pass through the transverse means. The locking means 29, 29 at both ends of the PC steel material 28 are locked to the outer surfaces of the side wall blocks 11, 11, and the PC steel material 28 is stretched by passing through the tightening of the locking means 29, 29 to stretch the assembly frame. 13 is configured.
Then, the plurality of assembly frames 13 configured in this manner are arranged in the horizontal direction, and extended and connected to an assembly hole that is opened in advance in the thickness direction (width direction) of the top plate block 10 and the side wall blocks 11 and 11. By inserting the steel material 30, the both ends of the extended connection PC steel material 30 are locked by locking means (not shown), and the side-by-side assembly frame bodies 13 are integrally connected to each other. Constitute.

  The transverse PC steel material 28 inserted into the sheath means 22, 24, 22 of the side wall block 11 and the bottom plate block 12 has a symmetrical shape relationship with the PC steel material 17 embedded in the top plate block 10, and the engagement between both ends is as follows. The side wall blocks 11 and 11 and the bottom block 12 are connected more firmly than the conventional one by the tension of the fastening means 29 and 29.

As a result, in the bottom block 12, the inner side of the intermediate portion is greatly crushed by the meat stealing portion 23 to reduce the weight, but the PC steel materials 28, 28 are disposed on both sides of the meat stealing portion 23, thereby providing a bending moment. A large strength is ensured by the tension of the PC steel materials 28 and 28 in the inner part (the part near the inner space 15 in FIG. 1) where M3 (see FIG. 13) acts greatly inward.
Further, in the leg piece 11b of the side wall block 11, the strength of the outer portion (the lower portion of the leg piece 11b) of the leg piece 11b to which the bending moment M3 (see FIG. 13) acts greatly in the outward direction is also passed through. 28, the bending moment M3 acting on the bottom plate block 12 and the leg piece 11b of the side wall block 11 after the construction can be well resisted.

  Further, in this embodiment, the length of the top plate block longitudinal direction of the top plate block 10 and the side wall block 11 is set to be longer than the length of the top plate block inside and outside the top plate block 10c. , 10c, 11c, and 11c are increased toward the end portion side of the top block 10 and the side wall block side of the leg piece 11b, so that the vicinity of both ends of the top plate block 10 and the leg pieces of the side wall block 11 are increased. It is possible to secure a strength that can sufficiently withstand the shearing force that acts greatly in the vicinity of the base portion of 11b.

  Next, second to fourth embodiments of the present invention will be described with reference to FIGS. In the description of the second to fourth embodiments, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  The super large box culvert 40 of the second embodiment shown in FIGS. 5 and 6 has a longitudinal PC steel material 41 used for connecting the top plate block 10 and the side wall block 11 with a curved arrangement which is a feature of the present invention. An in-situ bottom plate 42 is used in place of the bottom plate block of the first embodiment, and the top plate block 10 includes the meat stealing recess 16, the PC steel materials 17, 17 and the sheath means 18, 18 as in the first embodiment. Is provided.

In the side wall block 11, a meat stealing recess 21 is provided along the longitudinal direction of the side wall block 11 in the inner center portion of the main body 11a, and sheath means 22 and 22 are provided in the leg piece 11b.
Longitudinal PC steel material 41 is embedded on both sides of the body 11a sandwiching the meat stealing recess 21 (near the internal space 15 in FIG. 5). The longitudinal PC steel material 41 is an extension piece of the side wall block 11. The side wall block 11 is inclined outwardly toward the connection side end direction and the lower end part direction, respectively, and the side wall block 11 has an outer side of the side wall block 11 in the vicinity of the extension piece connection side end part and the lower end part (see FIG. 5 in the opposite direction to the internal space 15).

The longitudinal PC steel material 41 uses an unbonded PC steel stranded wire in which a lubricating film such as a polymer material is coated on the surface of a PC steel stranded wire obtained by twisting a plurality of PC steel wires. One end side 41a of the steel material 41 is protruded from the extension piece connection side end of the side wall block 11, and the locking means 43 fixed to the other end is fixed to the lower surface of the leg piece 11b.
The sheath means 18 and 18 of the top plate block 10 and the one end side 41a of the longitudinal PC steel material 41 protruding from the extension piece connecting side end of the side wall block 11 are located between the top of the side wall blocks 11 and 11. By erection, they are aligned outside (in the direction opposite to the internal space 15 in FIG. 5).
Then, one end side 41a of the longitudinal PC steel material 41 is inserted into the sheath means 18 of the top plate block 10, and the locking means 44 fixed to the one end side 41a is locked to the upper surface of the top plate block 10, and this engagement is further performed. By tightening the fastening means 44 and stretching the longitudinal PC steel material 41 inside and outside the side wall block 11 and the top block 10, the longitudinal PC steel material 41 has the required strength as an ultra-large box culvert 40. The top block 10 is connected to the side wall blocks 11 and 11.

  The on-site bottom plate 42 has bar arrangements 45 and 45 incorporated in two upper and lower stages in the installation space between the leg pieces 11b and 11b of the side wall blocks 11 and 11 arranged opposite to the operation site, and between these bar arrangements 45 and 45, A guide pipe is disposed as the sheath means 46, both ends of the guide pipe are connected to the openings of the sheath means 22 and 22 of the leg pieces 11b and 11b, and the concrete 47 is poured into the bottom plate installation space to be solidified. A bottomed plate 42 is formed, and a sheath means 46 using a guide pipe is linearly provided on the inside (upper side in FIG. 5) of the in-situ bottomed plate 42.

  After the in-situ bottom plate 42 is formed in this way, a transverse PC using a PC steel stranded wire is used for the sheath means 22, 46, 22 continuous in the inside and outside of the in-situ bottom plate 42 and the side wall blocks 11, 11. The steel material 28 is inserted, both ends of the side-through PC steel material 28 protruding outward from the ends of the sheath means 22 and 22 of the side wall blocks 11 and 11 are locked by the locking means 29, respectively. The side wall blocks 11 and 11 and the in-situ bottom slab 42 are connected to each other with a required strength by tightening the side-by-side PC steel material 28 by retightening.

  The super large box culvert 50 of the third embodiment shown in FIG. 7 is provided with a meat stealing recess 52 in the longitudinal direction of the bottom slab block 51 on the inner side of the bottom slab block 51 (inside the internal space 15 in FIG. 7). Sheath means 53 and 53 comprising guide holes are formed through both sides of the recess 52, and the sheath means 22 and 22 of the side wall blocks 11 and 11 are connected to both ends of the sheath means 53. The side wall blocks 11 and 11 and the bottom plate block 51 are connected to each other by inserting the PC steel material 28 through, and the top block 10 and the side wall blocks 11 and 11 are configured in the same manner as in the second embodiment.

The ultra-large box culvert 60 of the fourth embodiment shown in FIGS. 8 to 11 is obtained by dividing the side wall blocks 11 and 11 of the second embodiment, the bottom plate block 12 of the first embodiment, and the top plate block 61 into three parts. Used.
The top block 61 is composed of a straight intermediate piece 61a pre-cast at a factory or the like and L-shaped end pieces 61b and 61b. The intermediate piece 61a and the end pieces 61b and 61b are connected to each other. In the side ends, opposite stepped portions are set, and a pair of PC steel materials 62 and 62 and two sets of auxiliary PC steel bars 63a and 63b are used for these connections.

As shown in FIG. 10 and FIG. 12, the splitting surface of the intermediate piece 61a and the end pieces 61b and 61b has this bending moment so that the bending moment M1 acting on the top block 61 from above is substantially zero. It is set on intersections P1 and P1 between the longitudinal center line L1 that equally divides M1 and the thickness of the top block 61.
The intermediate piece 61a is provided with a meat stealing recess 64 in the inner central portion along the longitudinal direction of the intermediate piece 61a, and guide holes and guide pipes are formed on both inner sides of the intermediate piece 61a sandwiching the meat stealing recess 64. The sheath means 65a, 65a using either of these is provided penetrating in the longitudinal direction of the intermediate piece 61a.

A pair of auxiliary PC steel rods 63a, 63a are embedded inside the sheath means 65a, 65a on the outer side of both ends of the intermediate piece 61a, respectively, and one end of each auxiliary PC steel rod 63a is an intermediate piece. The other end is exposed in a free state at the end piece connection side end, and a connecting coupler 66a is fixed to the other end.
The four auxiliary PC steel bars 63a of the intermediate piece 61a are embedded when the intermediate piece 61a is manufactured in precast concrete, and the end piece is connected when the intermediate piece 61a and the end pieces 61b and 61b are connected. Since it is pulled in the direction, it is desirable to use an unbonded PC steel rod whose surface is coated with a lubricating film such as a polymer material.

Each of the end pieces 61b and 61b is provided with a horizontally long haunch 61c similar to that of the first embodiment at the inner corner, and sheath means 68, 68, 65b and 65b are provided at the inner and outer sides of the end piece 61b. The sheath means 18 and 18 for the PC steel material 41 are formed so as to penetrate through the piece 61b in the longitudinal direction.
The outer sheath means 65b, 65b are used for the main connection between the intermediate piece 61a and the end pieces 61b, 61b, and the outer sheath means 68, 68 are similarly used for the intermediate piece 61a and the end piece 61b, It is used to assist the connection with 61b, and guide holes or guide pipes are used for these sheath means 65b and 68.

  The sheath means 65b for main connection provided on the end piece 61b is at the inner side position that matches the sheath means 65a of the intermediate piece 61 at the connection side end with the intermediate piece 61, and ends from the matching position. The end piece 61b is inclined outwardly toward the outer end portion of the portion piece 61b, and is positioned outside the end pieces 61b and 61b in the vicinity of the outer end portion of the end piece 61b.

The intermediate piece 61a and the end pieces 61b and 61b of the present embodiment configured as described above are transported to the construction site in a divided state and are integrally connected as a top block 61 at the construction site. At the construction site, the end pieces 61b and 61b are arranged on both ends of the intermediate piece 61 and the stepped ends are overlapped, thereby the sheath means 65a and 65b of the intermediate piece 61 and the end pieces 61b and 61b. , 65b are continuous, and the auxiliary PC steel bars 63a, 63b are opposed to each other.
Then, a PC steel material 62 using a PC steel stranded wire is inserted into each of the continuous sheath means 65a, 65b, 65b, and protruded outward from the outer end portions of the sheath means 65b, 65b of the end pieces 61b, 61b. The both ends of the PC steel material 62 are locked by the locking means 24, and the locking means 24 is tightened and the PC steel material 62 is stretched, whereby the intermediate piece 61a and the end pieces 61b and 61b are connected. The top block 61 is integrally connected.

  Further, when the PC steel material 62 is inserted and tightened, an auxiliary PC steel bar 63b separate from the auxiliary PC steel bar 63a of the intermediate piece 61a is inserted into the sheath means 68 of the end piece 61b, and this auxiliary PC steel bar is inserted. The coupler 66b fixed to 63b is connected to the coupler 66a of the auxiliary PC steel rod 63a of the intermediate piece 61, and the end of the auxiliary PC steel rod 63b inserted into the sheath means 68 is connected to the end piece 61b by the locking means 67. Increasing the connecting force between the intermediate piece 61a and the end pieces 61b and 61b by engaging the outer end PC members 63a and 63b by tightening the locking means 67. To do.

  In this embodiment, the top plate block 61 is precast-molded into three pieces 61a, 61b, 61b, and these are integrally connected at the construction site with the PC steel material 62 and the auxiliary PC steel bars 63a, 63b with the required connection strength. Therefore, by using such a divided configuration and a construction method, precast molding and transportation to the construction site are facilitated, and the length of the top plate block 61 that is integrally connected can be set longer than the conventional one. Therefore, it can be set as the super-large box culvert 60 with a super-large opening width.

  Although the super large box culvert 60 of the fourth embodiment using the three-part top plate block 61 has been described using the auxiliary PC steel bars 63a and 63b, the present invention omits the auxiliary PC steel material. It is also possible to implement.

It is a cross-sectional front view of the super-large box culvert which shows 1st Example of this invention. It is a perspective view of the same very large box culvert which shows 1st Example of this invention. It is the top view for super-large-sized box culverts which shows 1st Example of this invention, and its sectional drawing. It is the side view for super-large-sized box culverts which shows 1st Example of this invention, and its sectional drawing. It is a cross-sectional front view of the super-large box culvert which shows 2nd Example of this invention. It is a perspective view of the super-large box culvert which shows 2nd Example of this invention. It is a cross-sectional front view of the super-large box culvert which shows 3rd Example of this invention. It is a perspective view of the super-large box culvert which shows 4th Example of this invention. It is a cross-sectional front view of the super-large box culvert which shows 4th Example of this invention. It is the cross-sectional front view and side view of the top plate block which show 4th Example of this invention. It is a top view of the top plate block which shows 4th Example of this invention. It is explanatory drawing of the bending moment which acts on the top plate block of 4th Example of this invention. It is explanatory drawing of the bending moment which acts on a box culvert.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10,61 ... Top plate block 10a ... Main body part 10b ... Extension piece 10c, 11c ... Haunch 11 ... Side wall block 11a ... Main body part 11b ... Leg piece 12, 51 ... Bottom plate block 13 ... Assembly frame body 14, 40, 50, 60 ... Super large box culvert 15 ... Internal space 16, 21, 23, 52, 64 ... Meat stealing recess 17, 62 ... PC steel 20a, 20b, 41 ... Longitudinal PC steel 21, 23, 43, 65a, 65b, 68 ... Sheathing means 24, 25, 27, 29, 43, 44, 67 ... Locking means 28 ... Transverse PC steel material 30 ... Extended connection PC steel material 42 ... In-situ bottom plate 47 ... Concrete 61a ... Intermediate piece 61b ... End piece 63a , 63b ... Auxiliary PC steel bar 66a, 66b ... Coupler

Claims (9)

A top plate block and left and right side wall blocks made of precast concrete, and a bottom plate block or on-site bottom plate made of precast concrete are connected with vertical PC steel and horizontal PC steel to form an assembly frame In a precast box culvert that forms a box culvert by arranging a plurality of the assembly frames in the horizontal direction and integrally connecting them with an extended connection PC steel material,
A PC steel stranded wire in which a meat stealing recess is formed along the longitudinal direction of the top plate block in the middle portion inside the middle portion of the top plate block, and a plurality of PC steel wires are twisted on both sides of the top plate block Is embedded as PC steel, and both ends of the PC steel are engaged with both ends of the top block to stretch the PC steel,
The PC steel material is located in the reinforcing ribs left on both sides of the meat stealing recess at the middle part of the top plate block, and the PC steel material is placed in the direction toward both ends of the top plate block from the middle part of the top plate block. An ultra-large precast box culvert characterized in that the plate block is inclined outward and is embedded outside the top block at both ends of the top block. Extension pieces extending in the direction of the side wall block are provided at both end portions of the top plate block, and a haunch is provided at an inner corner of the extension piece and the top plate block. Set the length longer than the length in the direction of the top plate block orthogonal to this,
A leg piece projecting in the direction of the bottom plate block or the spot bottom plate is extended to the lower end portion of the side wall block, and a haunch is provided at an inner corner of the leg piece and the side wall block. The super-large precast box culvert according to claim 1, wherein the length in the direction is set to be longer than the length in the inside / outside direction of the top block perpendicular to the direction. An extension piece extending in the direction of the side wall block is provided at both ends of the top block, and a meat stealing recess is formed in the inner central portion of the side wall block along the longitudinal direction of the side wall block. Embedded in the both sides of the side wall block sandwiching the PC steel strands twisted a plurality of PC steel wires as the longitudinal PC steel material,
The longitudinal PC steel material is inclined in the outward direction toward the extension piece connection side end portion direction and the lower end portion direction of the side wall block, and near the extension piece connection side end portion and the lower end portion of the side wall block. While being located outside the side wall block in the vicinity, and projecting one end side of the longitudinal PC steel material from the extension piece connection side end,
The longitudinal PC projecting from the extension piece connection side end when the top plate block is horizontally mounted on top of the both side wall blocks and the extension piece is superposed on the extension piece connection side end of the side wall block. By inserting one end side of the steel material, and engaging one end portion of the longitudinal PC steel material to the outer end portion of the extension piece and stretching the longitudinal PC steel material, the top block and the both side wall blocks are Sheath means for connecting together is provided through the extension piece of the top block in the longitudinal direction of the side wall block,
As the sheath means of the extension piece, either a guide hole or a guide pipe is used, and the entire sheath means is an extension piece that matches the longitudinal PC steel material located at the extension piece connection side end of the side wall block. The super-large precast box culvert according to claim 1 or 2, characterized in that it is disposed outside. A meat stealing recess is formed in the inner central portion of the bottom plate block along the longitudinal direction of the bottom plate block, and either a guide hole or a guide pipe is used on both inner sides of the bottom plate block sandwiching the meat stealing recess. A sheath means is provided penetrating in the longitudinal direction of the bottom block,
When the bottom slab block is arranged between the leg pieces of the both side wall blocks, a PC steel stranded wire in which a plurality of PC steel wires are twisted is connected to the bottom slab block by the sheath means of the bottom slab block. A sheath means for integrally connecting the both side wall blocks and the bottom plate block by stretching the PC steel material by engaging both ends of the transverse PC steel material with the outer end portions of both leg pieces. , Provided on both sides of the leg pieces of the side wall block penetrating in the longitudinal direction of the bottom block,
Either one of a guide hole or a guide pipe is used as the sheath means of the leg piece, and the sheath means of the leg piece is in a position that matches the sheath means of the bottom slab block at the connection side end with the bottom slab block. The leg piece is inclined outwardly from the matching position toward the outer end portion, and is located outside the leg piece in the vicinity of the outer end portion of the leg piece. The super-large precast box culvert according to any one of 1 to 3. A top plate block and left and right side wall blocks made of precast concrete, and a bottom plate block or on-site bottom plate made of precast concrete are connected with vertical PC steel and horizontal PC steel to form an assembly frame In the method for constructing a precast box culvert that forms a box culvert by arranging a plurality of the assembly frames in the lateral direction and integrally connecting them with an extended connection PC steel material,
The top block is divided into an intermediate piece and two end pieces;
A meat stealing recess is formed in the inner central portion of the intermediate piece along the longitudinal direction of the intermediate piece, and either a guide hole or a guide pipe is used on both inner sides of the intermediate piece sandwiching the meat stealing recess. Provided the sheath means that penetrated in the longitudinal direction of the intermediate piece,
Each of the end pieces is provided with sheath means using either a guide hole or a guide pipe penetrating in the longitudinal direction of the end piece,
The sheath means of the end piece is at a position that matches the sheath means of the intermediate piece at the end of the intermediate piece connecting side, and the end portion extends from the matching position toward the outer end of the end piece. The piece is inclined outward, and is located outside the end piece near the outer end of the end piece,
PC steel in which both end pieces are arranged at both ends of the intermediate piece, the sheath means of the intermediate piece and the end piece are continuous, and a plurality of PC steel wires are twisted on the continuous sheath means The stranded wire is inserted as a PC steel material, and both ends of the PC steel material are engaged with the outer ends of the end piece, and the PC steel material is stretched. A method of constructing an ultra-large precast box culvert characterized by being connected together as a plate block. When precast concrete manufacturing the intermediate piece, the auxiliary PC steel bar is embedded in the longitudinal direction of the intermediate piece, the end of the auxiliary PC steel bar is exposed to the end piece connection side end,
The end piece is provided with a sheath means using either a guide hole or a guide pipe penetrating in the longitudinal direction of the end piece,
When connecting the end piece and the intermediate piece, a separate auxiliary PC steel rod is inserted into the sheath means of the end piece, and the auxiliary PC steel rod and the auxiliary PC steel rod of the intermediate piece are connected. 6. An auxiliary PC steel rod connected by a coupler and engaged with an end of an auxiliary PC steel rod inserted through the sheath means to an outer end of the end piece, and both auxiliary PC steel members are stretched. The construction method of the super-large precast box culvert described in 1. When the end piece is manufactured in precast concrete, the length in the longitudinal direction of the intermediate piece is set at the inner corner of the end piece and the extension piece from the outer end of the end piece toward the side wall block. In addition to integrally forming a haunch longer than the length of the intermediate piece inside and outside perpendicular to this,
When manufacturing the precast concrete for the side wall block, the length of the top block block in the longitudinal direction is set at the inner corner portion of the side wall block and the leg piece protruding from the lower end portion of the end block toward the bottom plate block or the spot bottom plate. A method for constructing a super-large precast box culvert according to claim 5 or 6, wherein a haunch having a length longer than the length in the direction of the top and bottom blocks perpendicular to the length is integrally formed. When manufacturing the precast concrete of the side wall block, in the inner central portion of the side wall block, a meat stealing recess is formed along the longitudinal direction of the side wall block, and on both sides of the side wall block sandwiching the meat stealing recess, A PC steel stranded wire obtained by twisting a plurality of PC steel wires is buried as the longitudinal PC steel material,
The longitudinal PC steel material is inclined in the outward direction toward the extension piece connection side end portion direction and the lower end portion direction of the side wall block, and near the extension piece connection side end portion and the lower end portion of the side wall block. In the vicinity, each is located outside the side wall block, and one end side of the longitudinal PC steel material protrudes from the extension piece connection side end,
When manufacturing the precast concrete for the end piece, a sheath means using either a guide hole or a guide pipe is provided on the extension piece from the outer end of the end piece toward the side wall block. Provided through the direction, the entire sheath means of the extension piece is arranged outside the extension piece that matches the sheath means of the side wall block,
The end piece is disposed at the upper part of the side wall block, and one end side of the longitudinal PC steel material protruding from the extension piece connecting side end of the side wall block is inserted into the sheath means of each extension piece, The top plate block and both side wall blocks are integrally connected by engaging one end portion of the PC steel material with the outer end portion of the end piece and stretching the PC steel material vertically. Item 8. A method for constructing an ultra-large precast box culvert according to any one of Items 5 to 7. When producing the precast concrete for the bottom plate block, in the inner central portion of the bottom plate block, a meat stealing recess is formed along the longitudinal direction of the bottom plate block, on both inner sides of the bottom plate block sandwiching the meat stealing recess, A sheath means using either a guide hole or a guide pipe is provided through the longitudinal direction of the bottom block,
A sheath means using either a guide hole or a guide pipe is provided penetrating in the longitudinal direction of the bottom slab block on both sides of the leg piece protruding in the bottom slab block direction from the lower end of the side wall block,
The sheath means of the leg piece is in a position that matches the sheath means of the bottom plate block at the connection side end with the bottom plate block, and the leg piece as it goes from the matching position toward the outer end portion of the leg piece. Is inclined outward and is located outside the side wall block near the outer end of the leg piece,
The bottom plate block is disposed between the leg pieces of the both side wall blocks, the sheath means of the bottom plate block and both leg pieces is made continuous, and a PC in which a plurality of PC steel wires are twisted on the continuous sheath means The both-side wall block and the bottom plate block are formed by inserting a steel stranded wire as the cross-through PC steel material, and stretching the PC steel material by engaging both ends of the cross-through PC steel material with the outer ends of both leg pieces. The method for building an ultra-large precast box culvert according to any one of claims 5 to 8.

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