JPS6365784B2 - - Google Patents

Description

Detailed Description of the Invention ``Object of the Invention'' The present invention relates to a box culvert construction method, which constructs a box culvert with favorable workability, and also ensures excellent connection strength between each block and the reinforced concrete foundation slab. The aim is to dramatically increase the bending strength in the axial direction and to achieve low-cost construction.

Industrial applications Box culvert construction technology.

Conventional technology It is common for box culverts to be constructed by horizontally connecting rectangular cylindrical parts with integral molding on all four sides, but this type of construction with integral molding on all four sides only increases the production cost at the factory. Instead, it is bulky and heavy when transported to the site by truck, etc., and it is also difficult to set up and construct foundations on site. For this reason, recently, for example, Utility Model Publication No. 54-29658,
Designs using an inverted U-shaped block part and a bottom plate part as in Design Registration No. 487098 and Design Registration No. 469169, or by further dividing the inverted U-shaped block as in Japanese Patent Publication No. 53-25125. A box culvert made by combining two symmetrical inverted J-shaped blocks and a bottom plate body has been proposed.

Furthermore, in Japanese Utility Model Publication No. 54-7010, there is also a proposal for constructing an inverted U-shaped block in combination with a foundation frame having a hollow section.

Problems to be Solved by the Invention However, the box culvert, which has been commonly used in the past and whose four circumferences are integrally molded, is designed to have sufficient strength as a single block against external pressure loads, but its construction is difficult. , the individual blocks are simply installed in rows on the concrete foundation slab, and the axial bending strength of the rows is very weak against external pressure loads and is simply dependent on the strength of the foundation slab. There is.

Also, recently, a construction method has been implemented in which the block bodies arranged in a row are tightened with PC steel rods, but as will be explained later, the effect is small and the cost is high, and in the end it is inferior to the integral molded body. It's summery.

Further, in the case of using the conventional U-shaped block and bottom plate body or foundation frame as described above, there are hardly any concrete examples of construction, even if there are records of process proposals. In other words, the reason for this is that there is unavoidable strength anxiety due to the fact that it is divided into two or more parts, it is not easy to concrete the bottom slab at the construction site, and furthermore, it requires a large number of members and parts. Depends on complexity etc.

In other words, although forming the concrete parts in separate parts makes it easier to handle the cargo, it is inconceivable that the strength of the concrete parts assembled into a box would be greater than that of integrally formed parts, and it is a fact. Simply assembling members inevitably results in a product with low strength.

In terms of production at the factory, the number of parts is more than doubled, which makes it unavoidable, and the structure uses many bolts, nuts, washers, etc. to connect them, and each concrete member has to be inserted through the bolts. It is necessary to form holes and the like, which requires a fine structure, and requires a considerable number of man-hours to construct or work.

Moreover, the strength against external pressure, vibration, and strength against bending in the axial direction of the array depends solely on the strength of the above-mentioned connecting members or connecting parts, so it is not easy to obtain the desired strength, and in the end, is inferior to an integrally molded body.

Since it requires a large number of concrete members, a large number of connecting members, and a large number of man-hours, it cannot help but be quite expensive.

"Structure of the Invention" Means for Solving the Problems The bottom surface is opened and the welded member is set to be exposed inside the lower part of both side walls, and a tapered hole is formed in the top plate part with the top surface side as an enlarged part. a step of preparing a gate-shaped concrete block in which a tapered cover is fitted into the tapered hole; a step of pouring a reinforced concrete foundation base slab on-site continuously in the axial direction of the gate-shaped concrete block; The step of setting the above-mentioned gate-shaped concrete block and welding connection with the metal member from the foundation bottom slab through the welded member provided on the gate-shaped concrete block, and pouring invert concrete through the taper hole of the top slab. 1. A method for constructing a box culvert, comprising: a step of continuously and integrally forming a box culvert in the shape of a box girder; and a step of fitting a tapered lid into the tapered hole.

Function Gate-shaped concrete blocks with open bottoms are placed in rows on a continuous reinforced concrete foundation base slab.
A strength relationship is established in which the members to be welded exposed on both sides of the bottom of the gate-shaped concrete block body are connected by welding to reinforcing bars or reinforcements planted in the foundation bottom slab concrete.

By connecting the gate-shaped blocks arranged in a row with the foundation bottom plate, only by preventing displacement, a significantly superior axial bending strength can be achieved. In other words, the connecting parts only prevent misalignment between them, and have a box girder structure that increases bending strength.Therefore, there is no need to provide many connecting parts, and great strength can be economically achieved. urge

The gate-shaped concrete blocks with open bottoms can be combined and handled as appropriate, making it easy for curing in the factory, storage of parts, transportation to the construction site, and cargo handling operations such as setting. The members to be welded inside the lower part of the side wall can be accurately provided by joining and setting on the mold surface, and since the tapered hole has a relatively large diameter, there is no complication in molding. The concrete block body produced in a factory is essentially a single body, and from this point of view as well, there is no complexity.

The tapered hole at the top plate serves for the injection of invert concrete and for lighting. In other words, it is used as a fresh concrete input port to easily feed fresh concrete from directly above, and under the condition that many blocks are connected in series, light rays from the outside world are guided inside, and concrete raking and surface finishing operations can be carried out accurately. .

The poured inverted concrete encases the materials to be welded and the metal members from the foundation slab as described above, creating a corrosion-resistant condition, and solidifies the surroundings of these members, so that they can be protected against stress when subjected to a load. Prevents large stress from acting on the weld area.

After concrete is poured and finished, the tapered hole is stably closed by fitting the tapered lid into the tapered hole, resulting in a box culvert with a sufficiently high closed section in terms of strength.

The cast-in-place bottom slab or its reinforcing bars are welded and integrated with the exposed welded material to form a box girder shape and form an excellent bending strength relationship against external pressure loads.

Examples Specific embodiments of the present invention as described above will be explained with reference to the accompanying drawings. As described above, the present invention includes a gate type concrete block preparation process, a reinforced concrete foundation bottom slab on-site casting process, The present invention relates to sequentially performing a welding connection process with a member to be welded, an invert concrete placement process, and a taper lid fitting process. These steps will be explained in order as follows.

Gate-shaped concrete block preparation process.

As shown in Fig. 1, a gate-shaped concrete block 1 has an open bottom surface and serves as a casting surface 2 for pouring concrete on site, and at least a portion of the welded member 4 is placed on both sides of the bottom. It is exposed and provided. Further, a tapered hole 3 with an enlarged diameter portion on the outer surface side is formed in the top plate portion of such a concrete block body 1, and a tapered lid 5 to be fitted into the tapered hole 3 is separately prepared. be done.
The diameter of the taper hole 3 is at least 100 mm or more, and such a taper hole 3 is fundamentally different from a hole with a diameter of 10 to 20 mm, such as an insertion hole for a tightening bolt, and can be formed easily and accurately. Needless to say, it will happen. The taper angle of the tapered hole 3 and the tapered lid 5 fitted therein is generally about 10 to 30 degrees, preferably about 13 to 27 degrees. That is, by adopting a taper angle of this degree, the pressurizing force applied to the tapered lid 5 and its surroundings is effectively dispersed through the tapered surface, thereby preventing damage to the tapered lid 5 and the tapered hole 3 portion. There is no. Of course, the tapered lid 5 fitted with such a taper is stably aligned with the top plate surface of the block body,
No stepped portions or the like occur.

Gate-shaped concrete block body 1 as described above
As is well known, reinforcing bars are placed on the structure and it is constructed as a reinforced concrete structure. The welding member 4 to which the anchor reinforcing bar 9 is welded can be exposed accurately on the surface of the block body 1 by attaching it to the surface and filling and molding fresh concrete under the set conditions as shown in FIG. For such a member to be welded 4, an eighth steel material 6 having a different diameter having a screw hole 6a is attached as necessary.
- It can be installed as shown in Figure 11. In addition, if it is necessary to connect the top plates of the blocks 1, 1... in the axial direction, the 12th
- A recessed portion for attaching a connecting member as shown in FIG. 14 can be formed.

As shown in FIG. 1, the concrete block body 1 is provided with joint concrete filling grooves 1b for waterproofing water leakage at both ends to achieve a connection without leakage.

Reinforced concrete on-site pouring process.

As shown in FIG. 2 or 3 to 7, a continuous reinforced concrete foundation slab 12 is poured at the construction site.

This process itself is basically the same as the conventional one, and a foundation stone 11 such as crushed stone or chestnut stone is placed at the bottom of an excavation trench 10 formed at the site as shown in Figure 3. The reinforced concrete foundation bottom plate 12 is laid and compacted on the foundation stone 11.
The concrete block body 1 obtained in the above-mentioned preparation process is set on such a foundation slab 12. Foundation stone 11 as described above
It is well known that the layers and base plate 12 are required to some extent even when setting a conventional box culvert with an open bottom surface, and in this respect, the method of the present invention is particularly advantageous. It is not so complicated as to cause an increase in costs.

When the different-diameter steel material 6 having the screw holes 6a shown in FIGS. As shown in FIG. 10 or FIG. 11, it is preferable to bend the base plate as appropriate and expose it to the upper surface of the foundation bottom slab 12.

Welding connection process with parts to be welded.

The block body 1 is carried in and set as shown in FIG. 4 on the base base plate 12 formed as shown in FIG. 3, and in this state, the members to be welded and the metal members from the base base base plate 12 are welded and connected.

5th to 7th metal members from the foundation bottom plate 12 side
The one in the figure uses a joint reinforcing bar 7, and one of the preferred methods for setting this joint reinforcing bar 7 on site is to use a chemical coagulant, and the foundation bottom slab 12 is simply flattened in the usual manner as described above. For finishing, a hole is drilled into the foundation bottom slab 12 that has been cast in this way, and the lower half of the joining reinforcing bar 7 is inserted under conditions filled with a chemical coagulant, and the joining reinforcing bar 7 is placed on the 4 faces of the members to be welded. By coagulating and fixing the jointed reinforcing bars 7
is tightly attached to the 4th surface of the member, and is accurately joined by welding 7b. It is preferable that the joint reinforcing bars 7 are set at least at both ends of the concrete block body 1 in a symmetrical relationship as shown in FIG. 6B.

The advantage of using such a chemical coagulant is that the perforations can be placed in any position and direction in the foundation slab 12, which is useful for on-site construction of this type of civil engineering work, where dimensional errors are unavoidable on site. Joint reinforcing bar 7 that has a precise joining relationship with the member to be welded 4
Therefore, the welding between these two members 4 and 7 can be performed effectively.

When a different diameter steel bar 6 having a screw hole 6a as shown in Figs. 8 and 9 is used, a connecting reinforcement 26 is screwed into the screw hole 6a to protrude as shown in Figs. 10 and 11. The joint reinforcement 26 is bent as described above and made to run along the reinforcement 22 protruding from the foundation bottom slab 12. In this case, those connecting reinforcements 26 and reinforcement 22
is not always attached accurately,
These lines 26, 22 have a certain length and can be bent to a certain extent, so it is possible to make at least the weld 22a parallel.
A preferable weld 22a between both the reinforcements 26 and 22 can be formed.

Block body top plate connection process.

Once the block body 1 is set as described above, the invert concrete placing process will begin, which will be described later. However, if the soil layer subsidence or uplift is expected due to the soil quality of the construction site, the block body 1 that has been set in series will be 1, 1... It is preferable to connect their top plate parts between them.

Regarding the connection of such top plate parts, it is of course possible to connect the block bodies 1 and 1 using conventionally used bolts, nuts, washers, etc., but concrete blocks for this purpose may be used. It is not always easy to form holes for bolt insertion into the body with high precision. Further, a certain gap remains between the drilled hole and the inserted bolt, and because of this gap, the connection relationship is not stable, and it is not easy to fill and close this gap because it is a small gap. In other words, under these circumstances, the method provided by the present inventor is as shown in FIGS. 12 to 14.

That is, the one shown in FIG. 12 has a tightening plate 19 on the top of the side surface of the block body 1 as shown in FIGS. 15 to 17.
In the one shown in Fig. 13, a U-shaped groove 24 is formed between adjacent block bodies 1, 1, and a reinforcing bar bent at both ends in a U-shape is inserted into this groove, and then the mortar is inserted. Or filled with concrete. Furthermore, in the one shown in FIG. 14, grooves 23 are formed on both sides of the top plate of the block body 1, and a series of connecting bars 28 are inserted across a plurality of block bodies 1, 1, 1, etc., and mortar or the like is applied. It is filled and solidified.

As mentioned above, the structure using the tightening plate 19 shown in FIG. 12 is shown in detail in FIGS. A bolt 17 is screwed into each of these nuts 18, one bolt 17 is used as the shaft of the tightening plate 19, and the other bolt 17 is inserted into the receiving hole 15 provided in the tightening plate 19.
The eccentric plate 16 is inserted into the through hole 14 of the eccentric plate 16 and acts as a rotation center axis of the eccentric plate 16. That is, the eccentric plate 16 is provided with engaging portions 16a on its circumferential side, and by engaging the locking portion 13a of the rotary tool 13 with any of these engaging portions 16a, the eccentric plate 16 is connected to the bolt 17. Receiving hole 15 as the center
By rotating within the block, tightening (pulling operation of both block bodies 1, 1) corresponding to the amount of eccentricity can be obtained. In other words, the receiving hole 1 of the eccentric plate 16
By the rotation within the eccentric plate 5, a pull of a length corresponding to up to twice the eccentricity between the center points as shown in FIG. 16 can be obtained. By tightening using this method, the top plate sides of both blocks 1, 1 can be effectively tightened. In the device shown in FIGS. 15 to 17, the eccentric plate 16 can be manually rotated, and blocks of considerable weight can be joined easily and accurately on site.

Invert concrete placement process.

Block bodies 1, 1 arranged in the above manner
Invert concrete is poured into the open bottom part of . That is, this relationship is shown in Figure 6A,
A chute 27 is attached to the tapered hole 3 of one of the concrete blocks 1 in one row of blocks arranged as shown in FIG. Place concrete. This casting of invert concrete 8 using a chute is generally performed sequentially from one end to a plurality of concrete blocks 1, 1, etc. arranged in a series as described above. However, when pouring and pouring such inverted concrete, each tapered hole 3 into which concrete is not poured becomes a lighting section, that is, the concrete blocks 1, 1, which are connected over a distance of at least 10 m...in a group. ,
Particularly, the middle part is a dark place, but the external light from the taper hole 3 directly illuminates the inside, allowing for appropriate monitoring of the pouring condition. Since there is no concrete dropping except for 3, and the concrete is dropped from the lower end of the chute 27, an inverted concrete layer 8a is formed by leveling the concrete thrown close to the chute 27 inserted into the hole 3. Set up

The invert concrete 8 is made to have a thickness that sufficiently covers at least the members 4 to be welded and the welding portion as described above. That is, it is well known that preferable corrosion-resistant conditions are created by embedding metal members or welded parts in an inverted concrete layer in this way, and these members are protected from corrosive conditions and maintained at a predetermined strength. Ensure other characteristics are sufficient. Further, by embedding the peripheral side of such a member in the concrete layer, bending or other deformation thereof is prevented, which also contributes to improving the connection strength.

The above relationship is the same in the case of FIGS. 10 and 11, and the members 16 and 22 are solidified and fixed in the concrete 8 over a considerably long range.

According to the results of field studies conducted by the present inventors, those shown in Figs. 5 to 7 (10th and 1st
As shown in the construction example described later, it is possible to connect each concrete block body 1 with sufficient strength even if the concrete blocks 1 are not used together (as shown in Figure 1) alone, and the same relationship is obtained in the cases of Figures 10 and 11. , and by using them together, outstanding connection strength can be obtained.

Taper lid fitting process.

By fitting and fitting the taper lid 5 as described above into the taper hole 3, the outer surface of the concrete block body 1 can be finished smooth and the taper hole 3 can be effectively closed. The lid 5 does not fluctuate due to loads from above or vibrations. The tapered hole 3 with the lid 5 fitted has sufficient strength, and the circular tapered hole with the circular tapered lid shown in the figure is superior to the one that is integrally formed. No difference in strength was observed.

Other Embodiments The present invention in which the bottom surface is formed on-site using inverted concrete 8 can be subjected to various changes or processing on the bottom surface. For example, as shown in FIG. 7, the center of the bottom can be curved and recessed to smooth the flow of water, and a partition wall can be vertically formed in the middle to divide a plurality of waterways. Furthermore, a drainage channel can be formed on one or both sides, and the remaining part can be used as a walking surface, and a support stand for supporting the piping can be provided. Of course, the thicknesses of the base concrete 12 and the inverted concrete 8 can be appropriately selected in consideration of the ground strength of the construction area.

Construction example.

According to the results of actual construction by the present inventors, the width and height of the four sides connected and integrated are 500 mm each.
Gate type box culvert with concrete thickness of 45mm on both sides and 50mm on the top and bottom sides, but with an open bottom with the same width and height (therefore, the side wall height is 550mm, which is the addition of the 50mm bottom thickness of the box culvert) A concrete block was prepared, pressure was applied to the center of the top surface, and the pressure at which a crack first appeared was found to be 940 kg in the case of a box culvert whose four sides are closed and integrally formed. In contrast, the weight of a gate-shaped concrete block is 1040Kg, and the average value of a box culvert with four sides connected is 960Kg (860-1150Kg) according to the results of testing 5 pieces each. In the case of gate-shaped concrete blocks, the average value is 1006Kg.
(950-1100Kg). This shows that even with a gate-shaped concrete block, it is possible to obtain a compressive strength greater than that of a conventional box culvert that is integrally molded on all four sides.

It goes without saying that when box culverts of this type are connected in series, the pressure resistance properties of each concrete block as well as the strength in the direction of the connection axis are important. That is, the inventors of the present invention, in accordance with the above-mentioned present invention, designed the thickness of both side walls to be 130 mm.
A gate-shaped concrete block with a height of 1000 mm and a top plate thickness of 150 mm was manufactured, and the base concrete thickness was 100 mm, the inverted concrete thickness was 50 mm, and the length was set within this inverted concrete. Three 1500mm gate-shaped concrete blocks are connected and installed (the total length is
4500mm), each gate-shaped concrete block has a diameter of 13
Four anchor members made of steel bars with different diameters of mm are used to connect to the base concrete using only the chemical coagulant method. A test was conducted to measure the connection strength by forming fulcrums (4000 mm between the fulcrums) and applying a load to the center between these fulcrums, but it was found that there was no damage or cracking even with a load of 30 tons at the center. known. In this case, when only the base concrete and invert concrete were measured on a stand under the same conditions, cracks occurred at 2.4 tons.

In addition, for the concrete block of the present invention, a precast box culvert having the same dimensions and wall thickness as those described above according to the conventional method was manufactured, and three of these were connected to form a total length.
A specimen was prepared by inserting four PC steel rods with a diameter of 13 mm into a 4.5 m long specimen and tightening these rods with a tightening force of 8 tons. In other words, when this specimen was supported on fulcrums 250 mm from both ends and tested in the same way as above, cracks occurred in the side wall of the culvert under an external pressure load of 5 tons, and as the load increased, the number and length of the cracks increased. The load increased to 25 tons, and cracks appeared even in the top plate.

In other words, it is confirmed that the structure according to the present invention is significantly superior in strength in the direction of the connected axis as compared to such conventional box culverts.

The construction cost is estimated at 1200 yen by the inventors.
As a result of a detailed study of the material cost, construction cost, transportation cost, installation cost, etc. of various box culverts of ×1200 mm, 1500 × 1500 mm, and 2000 × 2000 mm, we found that the box culverts are significantly more efficient than conventional box culverts that are closed on all four sides. It has been confirmed that the method of the invention achieves a cost reduction of 60 to 40%, and also achieves a cost reduction of 10 to 34% compared to field-cast box culvert. Of course, in this case of on-site construction, the construction period would be long.

"Effects of the Invention" It is clear that the present invention as explained above has excellent workability on site in all aspects such as transporting and connecting parts to the site and placing invert concrete. As shown in the construction examples, it is possible to achieve the desired construction efficiently and achieve outstanding strength in a series of connected constructions.In addition, it is sufficiently low cost. This invention is industrially very effective because it ensures the following.

[Brief explanation of drawings]

The drawings illustrate embodiments of the invention,
Figure 1 is a partially cutaway slope view of concrete blocks according to the present invention, Figure 2 is a slope view of the connected construction state, and Figures 3 to 7 show the work process of connecting and forming box culverts with concrete blocks according to the present invention. In the explanatory drawings shown, Figs. 3 to 5 and 7 are sectional views, Fig. 6 is a cross-sectional view and a vertical sectional view, and Figs. 8 to 11 are welded objects according to the present invention. FIG. 7 is a partially cutaway cross-sectional view of the installed state, FIG. 9 is a front view thereof, and FIG.
FIG. 10 is a plan view of the used state, FIG. 11 is a sectional view thereof, and FIGS. 12 to 14 are slopes showing various aspects when the blocks according to the present invention are connected also at the top plate. Fig. 15 is an enlarged perspective view of the tightening plate portion of the one shown in Fig. 12, Fig. 16 is a front view of the eccentric plate portion, and Fig. 17
The figure is a sectional view thereof. However, in these drawings, 1 is a concrete block body, 2 is a cast-in-place concrete surface, 3 is a tapered hole, 4 is a member to be welded, 5 is a tapered lid, 6 is a buried steel material such as a steel material of different diameter, and 6a is a buried steel material such as steel material of different diameter. The screw hole, 7 is an anchor member, 8 is inverted concrete, 9 is reinforcement, 10 is an excavation groove, 11 is foundation stone, 12 is a reinforced concrete foundation bottom plate, 13 is a rotating tool, 14 is a through hole, 15 is a receiving hole , 16 is an eccentric plate, 16a is an engaging part thereof, 17 is a bolt, 18 is a nut, 19 is a tightening plate, 22 is a reinforcement, 22a is a welding part thereof, and 27 is a chute for pouring invert concrete. be.

Claims (1)

[Claims] 1. The bottom surface is open and the welded member is set to be exposed inside the lower part of both side walls, and a tapered hole is formed in the top plate part with the top surface side as an enlarged part, and the tapered hole is a step of preparing a gate-shaped concrete block into which a tapered lid is fitted; a step of pouring a reinforced concrete foundation base slab on-site continuously in the axial direction of the gate-shaped concrete block; a step of placing the gate-shaped concrete block on the foundation base slab; A process of welding and connecting metal members from the foundation bottom slab through the welded parts provided on the gate-shaped concrete block, and pouring and pouring invert concrete through the taper hole of the top slab to form a box girder shape. 1. A method for constructing a box culvert comprising the steps of: forming a box culvert continuously and integrally with the tapered hole; and fitting a tapered lid into the tapered hole. 2. A step of attaching anchor reinforcing bars fixed with resin to the holes formed in the reinforced concrete foundation base plate along with the members to be welded exposed inside the lower part of both side walls of the gate-shaped concrete block, and adding the anchor reinforcing bars and the above-mentioned members to be welded. The method for constructing a box culvert according to claim 1, comprising the step of welding and joining. 3 For a member to be welded having a screw hole, the rod-shaped member to be welded, which is attached to the screw hole of the member to be adhered, is set to protrude and expose from the inner surface of both side walls, and the foundation bottom plate is attached through the rod-shaped member to be welded. The box culvert construction method according to claim 1, wherein the box culvert is connected by welding to a metal member from. 4 Claims that include a step of interconnecting the tops of gate-shaped concrete blocks that are continuously provided in the axial direction between the step of pouring the reinforced concrete foundation slab on-site and the step of fitting the tapered lid into the tapered hole. The box culvert construction method described in Section 1. 5. Claim 4 states that the step of connecting the tops of the gate-shaped concrete blocks to each other is carried out by rotating an eccentric plate with respect to a tightening plate attached across the concrete blocks to be connected. Box culvert construction method.