JP6971035B2 - How to build a piping structure - Google Patents

Description

The present invention relates to a piping structure for underground pipes.

Some power plants use large amounts of seawater to cool their turbines. The flow of this seawater can be simply shown as sea area ⇒ intake ⇒ intake channel ⇒ intake pit ⇒ pump ⇒ circulating water piping ⇒ turbine ⇒ circulating water piping ⇒ water discharge pit ⇒ discharge channel ⇒ flood port ⇒ sea area (for example, patent documents). 1).

Of these, most of the circulating water pipes have a large diameter of about 4 m to 5.5 m, and are often buried in the ground with an overburden of about 3 m to 8 m. Steel pipes are generally used for circulating water pipes. For example, when the inner diameter is 4.7 m, the wall thickness is about 35 to 50 mm. In addition, anticorrosion coating is applied to the inner and outer surfaces of the steel pipe.

Generally, when installing a steel pipe, the ground is excavated to form a crushed stone layer on the bottom of the excavation, and a frame made of H-shaped steel or precast concrete is placed on it. The steel pipes are installed on a gantry, and a plurality of steel pipes are joined in the longitudinal direction by welding. After installing the steel pipe, it will be backfilled with excavated soil.

Japanese Unexamined Patent Publication No. 2014-228148

The wall thickness of the steel pipe is determined in consideration of not only the water pressure from the inside but also the earth pressure from the outside, the water pressure, and the load on the vehicle. When a steel pipe has a large diameter, its wall thickness is often determined by buckling due to an external load such as the latter.

In order to prevent such buckling, the steel pipe needs to have a thick wall of about 35 to 50 mm as described above, and the amount of steel material increases, so that the material cost and the construction cost increase. Welding of thick steel pipes also takes time, which is a factor of cost increase.

Further, since the steel pipe is a hollow member, its resistance to buoyancy due to groundwater is small. Therefore, it is often necessary to take additional measures to prevent floating, such as increasing the soil cover and removing anchors, which is troublesome to construct.

Furthermore, maintenance of the anticorrosion coating on the inner surface of the steel pipe can be easily performed after the inside of the steel pipe has been dried up, but maintenance of the anticorrosion coating on the outer surface is not easy, and heavy corrosion protection and electric corrosion protection (galvanic anode method). Will be required and the initial cost and maintenance cost will increase.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a piping structure that can be easily constructed and has a low cost.

The present invention for solving the above-mentioned problems is a pipe structure buried in the ground, that is, a steel pipe in a substantially horizontal direction, a concrete provided around the steel pipe and in contact with the ground on the outside, and the steel pipe. It has a reinforcing steel material arranged around and embedded in the concrete, a stud bolt provided so as to project outward from the steel pipe and embedded in the concrete, and a pedestal on which the steel pipe is installed. The reinforcing steel material has a longitudinal reinforcing bar of the steel pipe and an annular reinforcing bar in the circumferential direction of the steel pipe, and the annular reinforcing bar in the circumferential direction of the steel pipe and the longitudinal reinforcing bar of the steel pipe facing vertically. The reinforcing bar at the position corresponding to the gantry is provided only at a position avoiding the gantry in the longitudinal direction of the steel pipe, the steel pipe is substantially cylindrical, and the gantry has an outer peripheral shape of the steel pipe on the upper surface. a piping structure construction method of that having a recess corresponding substantially arcuate shape, the width stopper member in the radial direction of the steel pipe was placed in the steel tube, the steel tube on the frame in this state It is a method of constructing a pipe structure characterized by including a step of installing and removing the width stopper immediately after installing the steel pipe and a step of placing the concrete.

In the present invention, the concrete around the pipe body can resist the load from the outside and prevent the pipe body from buckling. Therefore, it is only necessary to consider the internal water pressure of the pipe body, and the thickness can be made thin. As a result, a low-cost structure with a reduced amount of steel can be obtained, and material costs and construction costs can be significantly reduced.

In addition, since the weight per unit length of the pipe body can be reduced, the length per pipe body can be increased, the labor of transportation and installation can be reduced, and the work of joining the pipe bodies at the site can be reduced. In addition, since concrete can resist the buoyancy caused by groundwater, it is not necessary to take measures to prevent the pipe from rising, and construction can be done easily.

Further, since the pipe body is integrated with the concrete by the anchor member and the concrete is reinforced by the reinforcing steel material, it can withstand a larger load. In addition, the reinforcing steel material prevents cracks in the concrete, and corrosion of the outer surface of the pipe body due to the intrusion of moisture or the like from the cracks can be prevented.

It is desirable that a plurality of the stud bolts are provided in the circumferential direction of the steel pipe.
As a result, the buckling length in the circumferential direction of the tubular body is shortened, and the structure can be made more difficult to buckle.

The reinforcing steel is more and this with a circumferential direction of the reinforcing bars in the longitudinal direction of reinforcing bars and the steel pipe of the steel pipe, it is assumed cage-like surrounding the reinforcing steel tube, can be suitably reinforced concrete .. It is desirable that the concrete is cast in a plurality of times.

It is desirable that the cross section of the concrete in the direction orthogonal to the longitudinal direction of the steel pipe is substantially square.
In the present invention, concrete can be easily constructed in a substantially square shape by casting on site. If concrete is wound around a pipe in advance and transported and installed, the weight will be large and it will be a difficult task, but such is not necessary when concrete is placed on site.

The steel tube is substantially cylindrical, the cradle, and more and this having a substantially arcuate recess corresponding to the outer peripheral shape of the steel pipe to the upper surface, the arrangement of the tubular body is stabilized, thereby preventing deformation due to its own weight ..

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a piping structure that can be easily constructed and has a low cost.

The figure which shows the piping structure 1. The figure which shows the piping structure 1. The figure explaining the construction method of the piping structure 1. The figure explaining the construction method of the piping structure 1. The figure explaining the construction method of the piping structure 1. The figure explaining the construction method of the piping structure 1. The figure which shows the anchor member 15a, 15b, 15c.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

(1. Piping structure)
1 and 2 are views showing a piping structure 1 according to an embodiment of the present invention. FIG. 1 is a diagram showing a vertical cross section in the longitudinal direction of the piping structure 1, and FIG. 2 is a diagram showing a vertical cross section in a direction orthogonal to the longitudinal direction of the piping structure 1. 2 (a) and 2 (b) show cross sections in lines AA and BB of FIG. 1, respectively.

The piping structure 1 of this embodiment is buried in the ground 2. As described above, this piping structure 1 is for passing seawater for cooling the turbine of the power plant.

The piping structure 1 includes a steel pipe 11, concrete 13, an anchor member 15, a reinforcing steel material 17, a gantry 19, and the like.

The steel pipe 11 is a substantially cylindrical steel pipe body with both ends open, and has a relatively large diameter (for example, an inner diameter of about 4 m to 10 m). The steel pipe 11 is arranged in a substantially horizontal direction. A plurality of steel pipes 11 are arranged along the longitudinal direction of the pipe structure 1, and adjacent steel pipes 11 are joined to each other in the longitudinal direction. The joining of the steel pipes 11 is performed by welding the ends thereof. The wall thickness of the steel pipe 11 can be determined so as to withstand the internal water pressure, and can be a thin wall (for example, a wall thickness of about 13 mm).

The concrete 13 is provided around the steel pipe 11 so as to be in direct contact with the outer surface of the steel pipe 11. The concrete 13 is provided over the entire length of the steel pipe 11. In the present embodiment, the concrete 13 is cast in the field, and the cross section in the direction orthogonal to the longitudinal direction of the steel pipe 11 is substantially square. In the example of FIG. 2, it has a substantially rectangular shape, but it may have a substantially trapezoidal shape in which the lower side is shorter than the upper side.

The concrete 13 has a role of resisting an external load and preventing buckling of the steel pipe 11. Therefore, for the steel pipe 11, it is only necessary to consider the internal water pressure as described above, and the thickness can be made thin. The water pressure in the steel pipe 11 is also borne by the concrete 13 around the steel pipe 11 and the ground 2 in contact with the outside of the concrete 13.

The anchor member 15 is provided so as to project outward from the outer surface of the steel pipe 11 in the radial direction of the steel pipe 11, and is embedded in the concrete 13 around the steel pipe 11. A plurality of anchor members 15 are provided at intervals in the circumferential direction and the longitudinal direction of the steel pipe 11. A stud bolt or the like is used for the anchor member 15.

The steel pipe 11 is integrated with the concrete 13 by the anchor member 15. Further, since the steel pipe 11 is fixed to the concrete 13 by the plurality of anchor members 15 in the circumferential direction of the steel pipe 11, the buckling length in the circumferential direction of the steel pipe 11 is shortened (the buckling length is the circumferential direction of the steel pipe 11 of the anchor member 15). The steel pipe 11 has a structure that makes it difficult for the steel pipe 11 to buckle.

The reinforcing steel material 17 is arranged around the steel pipe 11 so as to surround the steel pipe 11, and is embedded in the concrete 13. The reinforcing steel material 17 is formed in a cage shape by a linear reinforcing bar 171 along the longitudinal direction of the steel pipe 11 and a circumferential reinforcing bar 173 along the circumferential direction of the steel pipe 11. The reinforcing steel material 17 is arranged inside the tip of the anchor member 15.

A plurality of reinforcing bars 171 are arranged at intervals in the circumferential direction of the steel pipe 11, and a plurality of reinforcing bars 173 are arranged at intervals in the longitudinal direction of the steel pipe 11. The distance between the reinforcing bars 173 is, for example, about 20 cm. The concrete 13 is reinforced by the reinforcing steel material 17 by the reinforcing bars 171 and 173 bearing the tensile force. Further, since the reinforcing steel material 17 prevents the concrete 13 from cracking, corrosion of the outer surface of the steel pipe 11 due to the intrusion of moisture or the like from the cracks is prevented.

The gantry 19 is a pedestal provided for installing the steel pipe 11, and is formed of precast concrete or the like. A plurality of pedestals 19 are arranged on the crushed stone layer 3 at intervals in the longitudinal direction of the steel pipe 11. The distance between the gantry 19s is, for example, about 5 m. The lower surface of the gantry 19 is flat, but the upper surface is recessed in a substantially arc shape corresponding to the outer peripheral shape of the steel pipe 11, and the outer periphery of the steel pipe 11 is in contact with the recess over the entire length of the arc of this recess. As described above, the steel pipe 11 is placed on the gantry 19. The length of the arc of the depression is, for example, a length corresponding to a range of the circumference angle of the outer circumference of the steel pipe 11 of 90 ° or more and 120 ° or less, but is not limited to this. The anchor member 15 and the reinforcing steel material 17 are arranged so as to avoid the gantry 19.

(2. Construction method of piping structure 1)
Next, a method of constructing the piping structure 1 will be described with reference to FIGS. 3 to 6. 3 to 6, (a) and (b) are views showing cross sections corresponding to FIGS. 1 and 2 (a), respectively.

In the present embodiment, the ground is first excavated to a depth deeper than the installation position of the steel pipe 11, then a crushed stone layer 3 is formed on the bottom of the excavation as shown in FIG. 3, and the gantry 19 is arranged on the crushed stone layer 3. Then, the steel pipes 11 are installed on the gantry 19, the joint portions of the adjacent steel pipes 11 are aligned, and then the steel pipes 11 are joined by welding.

Since the steel pipe 11 is thin, if it is laid down in a substantially horizontal direction, it is easily crushed in the vertical direction due to its own weight. Therefore, if necessary, width retaining materials such as round steel (not shown) are arranged in two or three directions along the radial direction of the steel pipe 11 in the steel pipe 11, and the steel pipe 11 is carried to the site in that state. It may be installed on the gantry 19. This width stopper can be removed at an appropriate stage after the installation of the steel pipe 11, for example, after the concrete 13 described later is placed.

After performing the installation work of the steel pipe 11 in this way, the anchor member 15 is installed on the outer surface of the steel pipe 11 as shown in FIG. Here, for example, a metal fitting for anchor installation (not shown) is attached to the outer surface of the steel pipe 11 in advance, the steel pipe 11 is installed on the gantry 19, and then the anchor member 15 is attached to the metal fitting. However, the present invention is not limited to this, and the anchor member 15 may be attached by welding or the like.

Next, as shown in FIG. 5, the reinforcing steel material 17 is arranged around the steel pipe 11. Reinforcing bars 171, 173 of the reinforcing steel material 17 can be fixed and arranged by connecting them to the anchor member 15.

Then, a formwork (not shown) is installed on the side of the steel pipe 11, and concrete 13 is placed as shown in FIG. Finally, when the side or the upper side of the concrete 13 is backfilled with excavated soil or the like, the piping structure 1 described with reference to FIGS. 1 and 2 is constructed.

In the present embodiment, the concrete 13 is cast once, but in consideration of prevention of the steel pipe 11 from rising and radial deformation due to the casting of the concrete 13, it is divided into a plurality of times such as two or three times. It is also possible to cast concrete 13. Since the steel pipe 11 is fixed to the concrete 13 in the range where the casting has been completed by the anchor member 15, it is possible to prevent the steel pipe 11 from floating or deforming in the radial direction with the concrete placement from the next time onward.

As described above, according to the present embodiment, the concrete 13 around the steel pipe 11 can resist the load from the outside and prevent the steel pipe 11 from buckling. Therefore, for the steel pipe 11, only the internal water pressure needs to be considered, and the thickness can be made thin. As a result, a low-cost structure with a reduced amount of steel can be obtained, and material costs and construction costs can be significantly reduced.

Further, since the weight per unit length of the steel pipe 11 can be reduced, the length per steel pipe 11 can be increased, the labor of transportation and installation can be reduced, and the joining work of the steel pipe 11 at the site can be reduced. For example, if a steel pipe with a wall thickness of 13 mm and a length of 15 m / piece is used instead of a steel pipe with a wall thickness of 35 mm and a length of 5 m / piece, the labor of transportation, installation and joining work can be significantly reduced. In addition, since the concrete 13 can resist the buoyancy caused by groundwater, it is not necessary to take measures to prevent the steel pipe 11 from floating, and the construction can be easily performed.

Further, since the steel pipe 11 is integrated with the concrete 13 by the anchor member 15 and the concrete 13 is reinforced by the reinforcing steel material 17, it can withstand a larger load. Further, the reinforcing steel material 17 prevents the concrete 13 from cracking, and can prevent corrosion of the outer surface of the steel pipe 11 due to the intrusion of moisture or the like from the cracks. Therefore, there is no need for electrical corrosion protection or the like on the outer surface of the steel pipe 11, and maintenance costs can be reduced.

Further, since a plurality of anchor members 15 are provided in the circumferential direction of the steel pipe 11 and the steel pipe 11 is fixed to the concrete 13 by these anchor members 15, the buckling length of the steel pipe 11 in the circumferential direction is shortened, and the steel pipe 11 is twisted. It can be a structure that does not easily buckle.

Further, since the reinforcing steel material 17 is formed in a cage shape surrounding the steel pipe 11 by the reinforcing bars 171 in the longitudinal direction and the reinforcing bars 173 in the circumferential direction of the steel pipe 11, the concrete 13 can be suitably reinforced by the reinforcing steel material 17.

Further, in the present embodiment, the concrete 13 can be easily constructed in a substantially square shape by casting on site. Transporting and installing a concrete 13 wound around a steel pipe 11 in advance is a heavy task due to its heavy weight, but it is not necessary when the concrete 13 is placed on site.

However, the present invention is not limited to this. For example, in the present embodiment, a stud bolt is used as the anchor member 15, but in addition, as shown in the anchor member 15a of FIG. It is also possible to use angle steels having different sizes) or CT shaped steels as shown in the anchor member 15b of FIG. 7B. Further, in the example of FIG. 7C, a deformed reinforcing bar is used as the anchor member 15c. As described above, various anchors to be attached to the steel pipe 11 can be considered.

Further, the shape of the gantry 19 is not particularly limited. However, if a substantially arcuate recess corresponding to the outer peripheral shape of the steel pipe 11 is provided on the upper surface as described above, the arrangement of the steel pipe 11 can be stabilized and deformation due to its own weight can be prevented, and the above-mentioned It is also possible to remove the width stopper.

Further, the steel pipe 11 is substantially cylindrical, but the present invention is not limited to this, and in some cases, it may be a square cylinder. Further, reinforcing reinforcing bars other than the reinforcing steel material 17 may be further embedded inside the concrete 13.

Further, in the present embodiment, the pipe structure 1 is intended to allow seawater for cooling the turbine of the power plant to pass through, but the pipe structure 1 is not limited to this and can be applied to various underground pipes. Is.

Although the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to these examples. It is clear that a person skilled in the art can come up with various modified or modified examples within the scope of the technical idea disclosed in the present application, and these also naturally belong to the technical scope of the present invention. Understood.

1: Piping structure 2: Ground 3: Crushed stone layer 11: Steel pipe 13: Concrete 15, 15a, 15b, 15c: Anchor member 17: Reinforcing steel material 19: Stand 171, 173: Reinforcing bar

Claims (4)

It is a piping structure buried in the ground,
Approximately horizontal steel pipe and
Concrete that is provided around the steel pipe and whose outside is in contact with the ground,
Reinforcing steel materials placed around the steel pipe and buried in the concrete,
A stud bolt provided so as to project outward from the steel pipe and embedded in the concrete, and
The pedestal on which the steel pipe is installed and
Have,
The reinforcing steel material has a reinforcing bar in the longitudinal direction of the steel pipe and an annular reinforcing bar in the circumferential direction of the steel pipe.
The annular reinforcing bar in the circumferential direction of the steel pipe and the reinforcing bar in the longitudinal direction of the steel pipe at a position corresponding to the gantry in the vertical direction are provided only at a position avoiding the pedestal in the longitudinal direction of the steel pipe. Be ,
The steel pipe is substantially cylindrical and has a substantially cylindrical shape.
The cradle can be a method for constructing a piping structure that have a substantially arcuate recess corresponding to the outer peripheral shape of the steel pipe to the upper surface,
A step of arranging a width stopper along the radial direction of the steel pipe in the steel pipe, installing the steel pipe on the gantry in that state, and removing the width stopper immediately after installing the steel pipe.
The process of placing the concrete and
A method of constructing a piping structure characterized by including. The method for constructing a piping structure according to claim 1, wherein a plurality of the stud bolts are provided in the circumferential direction of the steel pipe. The method for constructing a piping structure according to claim 2, wherein the concrete is cast in a plurality of times. The method for constructing a piping structure according to any one of claims 1 to 3, wherein the cross section of the concrete in a direction orthogonal to the longitudinal direction of the steel pipe is substantially square.

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