JP7036614B2 - Pipeline burial structure and burial method - Google Patents

Description

The present invention relates to a pipeline burial structure and a burial method.

Pressure pipes such as water pipes are composed of a combination of curved pipes and straight pipes, but when a strong force such as an earthquake is received, a thrust force acts on the curved pipes, and the curved pipes are placed on both sides of the curved pipes. There is a risk of getting out of the connected straight pipe. As a result, water in the pipe may leak and cause great damage. In particular, if a liquefaction phenomenon occurs due to an earthquake, such damage may spread.

On the other hand, various pipeline structures have been proposed so that the curved pipe does not come out even when a thrust force acts on the curved pipe. For example, Patent Document 1 proposes a structure in which a mesh-like or sheet-like planar reinforcing material surrounds a soil material around a curved pipe to reinforce the circumference of the curved pipe.

Japanese Patent No. 4488724

However, the method of Patent Document 1 requires a special planar reinforcing material, which increases the cost and has a problem that it takes time to install the diploma reinforcing material. The present invention has been made to solve the above problems, and an object of the present invention is to provide a pipeline burying structure and burying method that can be constructed at low cost.

The present invention is a buried structure of a pipeline buried in the ground, and is a curved pipe unit including a curved pipe, a pair of connecting units connected to both ends of the curved pipe unit, and the connecting unit. A pair of straight pipe units connected to both ends and including at least one straight pipe, a first filler to be filled around the curved pipe unit in the ground, and around the connecting unit in the ground. A second filler is provided, and a first filler or a second filler is filled around the straight pipe unit in the ground, and the first filler fills each of the units. The second filler is made of a material that is fixed in the ground, and the second filler is made of a material that allows the movement of each unit in the ground.

In the buried structure of the pipeline, the connecting unit includes at least one straight pipe, and the curved pipe unit and the straight pipe unit can be connected by the straight pipe.

In the buried structure of each of the pipelines, the connecting unit can be configured by a joint connecting the curved pipe unit and the straight pipe unit.

In the buried structure of each pipeline, the curved pipe unit may include the curved pipe and a pair of straight pipes connected to both sides of the curved pipe.

In the buried structure of each of the above pipelines, the first filler may contain at least one of fluidized soil and soil cement.

In the burial structure of the pipeline, the second filler can include sand, crushed stone, and at least one of the soil excavated during the burial of the pipeline.

In the buried structure of the pipeline, the weight per unit volume of the first filler can be 1.2 to 2.1 t / m ³ .

The method of burying a pipeline according to the present invention includes a step of preparing a curved pipe unit including a curved pipe, a step of preparing a pair of connecting units to be connected to both ends of the curved pipe unit, and a step of preparing the connecting unit. A step of preparing a pair of straight pipe units connected to both ends and including at least one straight pipe, and when the curved pipe unit is buried in the ground, a first filler is placed around the curved pipe unit. The step of filling, the step of filling the second filling material around the connecting unit when the connecting unit is buried in the ground, and the step of filling the straight pipe unit in the ground, the straight pipe unit. The first filler is composed of a material for fixing each unit in the ground, and the second filler is provided with a step of filling a first filler or a second filler around the above. It is composed of a material that allows the movement of each of the units in the ground.

In the method of burying a pipeline, the first filler may contain at least one of fluidized soil and soil cement.

In the method of burying the pipeline, the second filler may contain sand, crushed stone, and at least one of the soil excavated at the time of burying the pipeline.

According to the present invention, the construction can be carried out at low cost.

It is a top view which shows a part of the pipeline (target pipeline) which concerns on one Embodiment of this invention. It is a target pipeline division plan view of FIG. It is a top view of the passage excavated in the ground to bury the pipeline. It is sectional drawing of FIG. It is sectional drawing explaining the burial of a pipeline. FIG. 5 is a plan view of FIG. It is sectional drawing explaining the burial of a pipeline. It is a top view explaining the behavior when a thrust force acts on a target pipeline. It is a top view which shows the other example of a target pipeline. It is a model diagram which concerns on embodiment of this invention. It is a model diagram which concerns on embodiment of this invention.

Hereinafter, an embodiment of the buried pipeline structure according to the present invention will be described with reference to the drawings. FIG. 1 is a plan view showing a pipeline which is a target of the buried structure of the present embodiment, and FIG. 2 is an exploded view of FIG.

<1. Outline of target pipeline ＞
The pipeline used in the buried structure of this pipeline is, for example, a pressure pipe through which a fluid acting under pressure such as a water pipe passes. The buried structure of the pipeline according to the present embodiment is a buried structure of a portion of the pipeline including a curved pipe. First, the pipeline of the portion included in the buried structure according to the present embodiment will be described. Hereinafter, the portion of the pipeline included in the buried structure according to the present embodiment will be referred to as a target pipeline 10.

As shown in FIGS. 1 and 2, the target pipeline 10 includes a curved pipe unit 1 having a curved pipe 11, a pair of connecting units 2 connected to both ends of the curved pipe unit 1, and each connecting unit 2. It includes a pair of straight pipe units 3 connected to each other. That is, the connecting unit 2 is connected between both ends of the curved pipe unit 1 and each straight pipe unit 3. Further, although not shown, the straight pipe unit 3 is connected to another part of the pipeline, that is, a straight pipe or another curved pipe.

The curved pipe unit 1 includes a curved pipe 11 and a pair of first straight pipes 12 connected to both ends thereof. The curved tube 11 includes a main body portion 111 formed in a cylindrical shape and having an axis line formed in an arc shape having a constant radius of curvature, and a pair of cylindrical receiving portions 112 integrally formed at both ends thereof. ing. The inner diameter of the receiving portion 112 is larger than the inner diameter of the main body portion 111.

On the other hand, the first straight pipe 12 is formed in a cylindrical shape and includes a main body portion 121 whose axis extends linearly. Here, both ends of the main body 121 are referred to as a first end portion and a second end portion, and a receiving portion 122 is integrally formed at the first end portion. The inner diameter of the receiving portion 122 is larger than the inner diameter of the main body portion 121. Further, the second end portion 1212 of the main body portion 121 has a size that can be inserted into the receiving portion 112 of the curved pipe 11.

Then, in order to connect the receiving portion 121 of the curved pipe 11 and the second end portion 1212 of the first straight pipe 12, a known sealing rubber material (not shown) is provided on the inner peripheral surface of the receiving portion 121 of the curved pipe 11. Is attached, and the outer peripheral surface of the first straight pipe 12 inserted into the receiving portion 121 and the inner peripheral surface of the receiving portion 121 are hermetically sealed. Further, a seal rubber material is also attached to the inner peripheral surface of the receiving portion 122 of the first straight pipe 12.

Next, the pair of connecting units 2 will be described. Both connecting units 2 have the same configuration, and each includes a second straight pipe 21 having the same configuration as the first straight pipe 12 described above. That is, the second straight pipe 21 has a cylindrical main body portion 211 and a receiving portion 212 integrally formed at the first end portion thereof. The second end portion 2112 of the main body portion 211 is inserted into the receiving portion 122 of the first straight pipe 12 so as to be liquidtightly connected. Further, a seal rubber material is also attached to the inner peripheral surface of the receiving portion 212 of the second straight pipe 21.

Subsequently, a pair of straight pipe units 3 will be described. Both straight pipe units 3 have the same configuration, and each includes a third straight pipe 31 having the same configuration as the first straight pipe 12 described above. That is, the third straight pipe 31 has a cylindrical main body portion 311 and a receiving portion 312 integrally formed at the first end portion thereof. The second end portion 3112 of the main body portion 311 is inserted into the receiving portion 212 of the second straight pipe 21 so as to be liquidtightly connected. Further, a seal rubber material is also attached to the inner peripheral surface of the receiving portion 312 of the third straight pipe 31. Then, another straight pipe or a curved pipe (not shown) is connected to the receiving portion 312 of the third straight pipe 31.

The curved pipe 11, the first to third straight pipes 12, 21, and 31 configured as described above can be formed of various materials, for example, the FRP pipe, the FRPM pipe, and other resin materials. It can be formed from a tube. The FRP tube is a tube made of fiber reinforced plastic. On the other hand, the FRPM tube is a tube in which an inner layer of FRP and an outer layer of FRP are laminated on the inner peripheral surface and the outer peripheral surface of the resin mortar layer, respectively, and these are integrally formed, but the number of layers is particularly limited. Not done.

<2. How to bury the target pipeline>
The target pipeline 10 configured as described above is buried in the ground as follows. Regarding this point, FIGS. 3 to 4 are diagrams illustrating a method of burying the target pipeline.

First, as shown in FIGS. 3 and 4, a passage 5 for arranging the target pipeline 10 is excavated in the ground. The passage 5 has a trapezoidal cross section, and the width of the bottom surface 51 is narrower than the width of the upper opening of the passage 5. However, the width of the bottom surface 51 is wider than the outer diameter of the target pipeline 10. Subsequently, the target pipeline 10 is arranged in this passage 5. At this time, the target pipeline 10 may be arranged directly on the bottom surface 51 of the passage 5, or the target pipeline 10 may be arranged via a pedestal if necessary. Further, if necessary, a known levitation prevention member can be provided. This is to prevent the target pipeline 10 from floating when the filling material described below is filled in the passage 5. Examples of the levitation prevention member include a band for fixing the target pipe 10 to the bottom surface 51 or a pedestal, an anchor for fixing the target pipe 10 to the passage 5, and a heavy object attached to the target pipe 10. be.

Next, as shown in FIGS. 5 and 6, the passage 5 is filled with the fillers 6 and 7. That is, the fillers 6 and 7 are filled between the target pipeline 10 and the wall surface of the passage 5. Here, two types of fillers are used. That is, as shown in FIGS. 3 and 6, in the region where the curved pipe unit 1 is arranged (hereinafter, the first region 100) and the region where the straight pipe unit 3 is arranged (the second region 200). , The first filler 6 is filled. On the other hand, the region where the connecting unit 2 is arranged (third region 300) is filled with the second filler 7. In this way, the first or second fillers 6 and 7 are filled in each region 100 to 300 of the passage 5 so as to cover the upper part of the target pipeline 10.

The first filler 6 is for restraining the curved pipe unit 1 and the straight pipe unit 3 in the ground, and for example, known fluidized soil, soil cement, and improved crushed stone (a mixture of cement and crushed stone). ), A stable liquid solidified body (for example, one in which soil or sand is hardened with a stabilizer containing bennite as a main component), air mortar, concrete containing a bubble material, or the like can be used. The fluidized soil is a backfill material produced by mixing earth and sand, water, and a solidifying material. Gravel soil or the like is used for the earth and sand, and cement or a cement-based solidifying material is used as the solidifying material. Further, the first filler 6 preferably has a specific gravity equivalent to that of the surrounding ground, and for example, the weight per unit volume is preferably 1.2 to 2.1 t / m ³ . Further, although concrete can be used as the first filler 6, it can be used as long as it is adjusted to have a specific gravity in the above range.

The second filler 7 allows the connecting unit 2 to move in the ground. That is, when the connecting unit 2 does not have a binding force above a certain level, for example, when an extreme force such as an earthquake acts on the second straight pipe 21, a frictional resistance force around the pipe is generated, but the frictional resistance. For a force exceeding the value, movement such as movement of the pipe itself, bending of the pipe, and removal from the receiving port of the connection destination of the pipe is allowed. As the second filler 7 having such a function, for example, sand, crushed stone, soil excavated at the time of burying a pipeline, or the like can be used.

Subsequently, as shown in FIG. 7, the upper part of each of the fillers 6 and 7 is filled with the soil 8 excavated during excavation of the passage to complete the work. The target pipeline 10 may be connected in the passage 5 after the units 1 to 3 are separately arranged in the passage. Alternatively, units 1 to 3 may be arranged in each region 100 to 300 to fill the fillers 6 and 7. For example, the curved pipe unit 1 is arranged in the first region 100, the first filler 6 is filled, and then the connecting unit 2 arranged in the second region 200 is connected to fill the second filler 7. Then, it is also possible to perform construction such as connecting the straight pipe unit 3 arranged in the third region 300 to the connecting unit 2 and then filling the first filler 6. The overburden of the first filler 6 and the second filler 7 is preferably 1 to 2 m.

<3. Features>
The buried structure configured as described above has the following effects. For example, as shown in FIG. 8, when an earthquake or a liquefaction phenomenon associated therewith occurs and a thrust direction force (force outward in the radial direction) F acts on the curved tube unit 1, the curved tube unit 1 becomes the first. 1 Since it is restrained by the filler 6, it is possible to prevent the curved pipe unit 1 from being deformed. For example, it is possible to prevent the curved tube 11 from bending so as to change the central angle, thereby preventing the curved tube 11 from being damaged. However, due to the thrust force F, the curved tube unit 1 moves together with the first filler 6.

On the other hand, the second filler 7 is filled around the connecting unit 2 connected to the curved pipe unit 1, but the second filler 7 does not restrain the connecting unit 2, so that the connecting unit is not constrained. 2 is pulled and moved by the curved tube unit 1 which is moved by the thrust force F. However, since the straight pipe unit 3 is restrained by the first filler 6, it is difficult to move, so that the connecting unit 2 changes the angle between the curved pipe unit 1 and the straight pipe unit 3. In addition, it is pulled by the curved tube unit 1.

At this time, the second straight pipe 21 of the connecting unit 2 may slightly come out of the receiving portion 122 of the first straight pipe 12, or the third straight pipe 31 may come out of the receiving portion 212 of the second straight pipe 21 to some extent. There is. However, if the insertion allowance for the receiving portions 122 and 212 is lengthened, the insertion allowance will not be completely removed and the connected state will be maintained.

As described above, since the connecting unit 2 is not constrained by the second filler 7, when the thrust force F acts on the curved tube unit 1, the angle of the connecting unit 2 changes to reduce the thrust force F. It can be absorbed and the connected state of each unit 1 to 3 can be maintained. Further, it is possible to prevent the curved tube 11 from being damaged as described above.

The above-mentioned buried structure can use known curved pipes and straight pipes, and can be realized only by changing the filler for burying them, so that it can be constructed at low cost.

<4. Modification example>
Although one embodiment of the present invention has been described above, the present invention is not limited to this, and various modifications can be made without departing from the spirit of the present invention. The following modifications can be combined as appropriate.

<4-1>
In the above embodiment, the curved tube unit 1 is composed of one curved tube 11 and two first straight tubes 12, but the present invention is not limited to this, and only the curved tube 11 or both ends thereof are used. A curved pipe unit 1 may be formed by connecting two or more straight pipes. Further, although the connecting unit 2 is composed of one second straight pipe 21, a plurality of straight pipes may be connected. Similarly, the straight pipe unit 3 can also be composed of a plurality of straight pipes.

<4-2>
In the curved pipe 11 and the first to third straight pipes 12, 21, and 31 described above, the receiving portion may be provided at any position, and may be configured so that adjacent pipes can be connected to each other. For example, in each pipe, a receiving portion may be provided on the opposite side to the above-described embodiment, or a receiving portion may be provided at both ends. Therefore, if the connection destination is provided with a receiving portion, it may be a curved pipe or a straight pipe having no receiving portions at both ends. Alternatively, the pipes can be connected to each other by a joint.

<4-3>
In the above embodiment, the second area 200 in which the straight pipe unit 3 is arranged is filled with the first filler 6, but the second area 200 can also be filled with the second filler 7. As a result, the straight pipe unit 3 can also be moved like the connecting unit 2, so that the force due to the movement of the curved pipe unit 1 can be absorbed.

<4-4>
In the above embodiment, the straight pipe 21 is used as the connecting unit 2, but the present invention is not limited to this, and for example, as shown in FIG. 9, the curved pipe unit 1 and the straight pipe unit 3 are connected. It may be a joint 2. Even in this case, the periphery of the joint 2 may be filled with the second filler 7. Then, the circumference of the curved pipe unit 1 may be filled with the first filler 6, and the periphery of the straight pipe unit 3 may be filled with the first or second fillers 6 and 7. If the connecting unit is long, for example, if it exceeds 4000 mm, it is preferable to use a straight pipe having a strong axial bending strength in consideration of bending that occurs during movement. For example, a straight pipe having a shaft bending strength of about 1.5 to 2 times the normal strength can be adopted. The axial bending strength of a normal 4 m reinforced plastic composite tube is, for example, as follows.

The range of filling each of the fillers 6 and 7 does not have to be strict, and it is sufficient that there is a boundary between the fillers 6 and 7 in the vicinity of the connection portion between the units 1 to 3. More specifically, the length in which each of the fillers 6 and 7 is filled is preferably the same as the length of each of the units 1 to 3, but an error of up to about 1 m is allowed for each. For example, the second region 200 may be shorter or longer than the connecting unit 2. Further, in order to facilitate the movement of the connecting unit 2, it is preferable that the second region 200 is longer than the connecting unit 2. From this point of view, it is easier to construct by first filling the second region 200 with the second filler 6 to secure a firm length, and then filling the first filler 6.

Hereinafter, examples of the present invention will be described. However, the present invention is not limited to the following examples.

First, as a model of the target pipeline showing this embodiment, a model as shown in FIG. 10 was created. This model has a curved pipe unit and a connecting unit, and the straight pipe unit is omitted. Therefore, it is assumed that the end portion of the connecting unit on the straight pipe unit side is fixed. In addition, the following conditions were set.
・ Caliber of curved tube unit: 500 mm
-Outer diameter of curved tube unit: 523 mm
-Length in the curved tube unit L1: 3000 mm
・ Angle θ1: 45 degrees in the curved tube unit ・ Diameter of the connecting unit: 500 mm
-Outer diameter of connecting unit: 523 mm
-Length L2 in the connecting unit: 5000 mm
-Set water pressure: 0.25 MPa
・ Soil cover: 1.5m

Subsequently, as shown in FIG. 11, it is assumed that the curved tube unit moves 400 mm in the X direction on the assumption that the thrust force acts. At this time, since the connecting unit is movable, it swings by 3.24 degrees (θ2) by calculation. Further, the escape amount L3 from the curved tube unit was 306 mm.

Generally, assuming that the allowable bending angle at the connecting portion is 4 degrees, the swing angle (bending angle) of the connecting unit is equal to or less than this allowable bending angle, as described above. Further, although the pull-out amount was 306 mm, if there is a connecting structure between the curved tube unit and the connecting unit having a larger insertion allowance, the connected state between the curved tube unit and the connecting unit can be changed. It turned out to be retained.

Therefore, if the connecting unit is configured to be movable according to the present embodiment, for example, by adjusting the insertion allowance of the connecting structure, the pipe line is separated even if the curved pipe unit receives a thrust force. It turned out that it can be prevented.

1 Curved pipe unit 11 Curved pipe 2 Connecting unit 21 Straight pipe 3 Straight pipe unit 31 Straight pipe 6 First filling material 7 Second filling material

Claims (10)

It is a buried structure of a pipeline buried in the ground.
With a curved tube unit including a curved tube,
A pair of connecting units connected to both ends of the curved tube unit,
A pair of straight pipe units connected to both ends of the connecting unit and containing at least one straight pipe.
A first filler to be filled around the curved pipe unit in the ground,
A second filler filled around the connecting unit in the ground,
Equipped with
The first filler is filled around the straight pipe unit in the ground.
The first filler is composed of a material that fixes each unit in the ground.
The second filler is a buried structure of a pipeline, which is made of a material that allows the movement of each unit in the ground. The pipeline structure according to claim 1, wherein the connecting unit includes at least one straight pipe, and the straight pipe connects the curved pipe unit and the straight pipe unit. The buried structure of a pipeline according to claim 1, wherein the connecting unit is composed of a joint that connects the curved pipe unit and the straight pipe unit. The buried structure of a pipeline according to any one of claims 1 to 3, wherein the curved pipe unit includes the curved pipe and a pair of straight pipes connected to both sides of the curved pipe. The buried structure of a pipeline according to any one of claims 1 to 4, wherein the first filler contains at least one of fluidized soil and soil cement. The buried structure of a pipeline according to any one of claims 1 to 5, wherein the second filler contains sand, crushed stone, and at least one of the soil excavated at the time of burying the pipeline. The buried structure of a pipeline according to any one of claims 1 to 6, wherein the weight per unit volume of the first filler is 1.2 to 2.1 t / m ³ . Steps to prepare a curved tube unit including a curved tube,
A step of preparing a pair of connecting units to be connected to both ends of the curved tube unit, and
A step of preparing a pair of straight pipe units that are connected to both ends of the connecting unit and include at least one straight pipe.
When the curved pipe unit is buried in the ground, the step of filling the first filler around the curved pipe unit and
When the connecting unit is buried in the ground, a step of filling a second filler around the connecting unit, and
When the straight pipe unit is buried in the ground, the step of filling the first filler around the straight pipe unit and
Equipped with
The first filler is composed of a material that fixes each unit in the ground.
The method for burying a pipeline, wherein the second filler is made of a material that allows the movement of each unit in the ground.
The method for burying a pipeline according to claim 8, wherein the first filler contains at least one of fluidized soil and soil cement. The method for burying a pipeline according to claim 8 or 9, wherein the second filler contains sand, crushed stone, and at least one of the soil excavated at the time of burying the pipeline.

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