JP6715098B2 - How to connect underground pipes - Google Patents

Description

The present invention relates to a connection structure for underground pipes. In particular, the present invention relates to a structure for connecting an underground buried pipe made of a flexible pipe with a spiral wave to a pipe through hole provided on a wall surface such as a handhole.

Conventionally, in order to fix the underground buried pipe to the wall surface of the handhole, etc., after inserting the tip of the underground buried pipe into the through hole for piping drilled in the wall surface of the handhole, etc., from the inside of the through hole for piping A tubular member having a trumpet-shaped opening called a bell mouth is screwed into the tip of the underground buried pipe by using the spiral shape of the pipe body of the underground buried pipe, and the underground buried pipe is fixed with an adhesive. It was fixed in the through hole for piping. Further, in Patent Document 1 and Patent Document 2, as a connection structure of the underground buried pipe to the handhole, a bell mouth member screwed to the inside of the underground buried pipe and to the outside of the underground buried pipe. A connection structure is disclosed in which a holder (tightening member) holds a wall of a handhole and fixes an underground pipe to a through hole for piping of the handhole.

Japanese Patent Laid-Open No. 11-266519 JP, 2009-130995, A

In the underground buried pipe connection structures of Patent Document 1 and Patent Document 2, a sealing member is sandwiched between the wall surface of the handhole and the holder (tightening member) so that water does not enter the inside of the handhole. The site needs to be sealed. Therefore, in such a underground buried pipe connection structure, while rotating the holder around the central axis of the pipe, advance it toward the wall of the handhole, and sandwich the wall of the handhole with the holder and bell mouth to complete the connection structure. Need to let. However, it is difficult to perform this tightening work so that the seal can be surely made.

That is, in the connection structure of the underground buried pipe of Patent Document 1 and Patent Document 2, since the seal member is provided between the relative rotating handhole wall surface and the holder during the connection operation, the seal member and the hand Strong friction may occur between the walls of the hole, making it impossible to fully tighten the holder. Especially when the pitch of the spiral of the underground buried pipe is large, such a tightening failure is likely to occur. On the other hand, if the pitch of the spiral of the underground buried pipe is small, even if the holder is rotated, the holder does not easily move forward, and the tightening work becomes complicated.

As described above, in the conventional underground buried pipe connection structure, the workability of the connection work is easily affected by the size of the spiral pitch of the underground buried pipe, and improvement thereof is desired. It was

An object of the present invention is to provide a method for connecting an underground buried pipe that is easy to tighten. That is, even when using an underground buried pipe having a predetermined pitch, a method for connecting an underground buried pipe is provided, which can adjust the amount of tightening torque and the speed of tightening operation. To do.

As a result of earnest studies, the inventor has constructed a fastening member by dividing it so as to have a flange member and a screw member, screwing the flange member and the screw member together, and the pitch of the screw and the underground embedding. The present invention has been completed by finding that the above problems can be solved by changing the pitch of the spiral of the tube to different pitches.

The present invention relates to a grounding pipe made of a flexible pipe with a spiral wave in a pipe through hole provided in a wall surface such as a handhole, and a fastening member screwed to the outside of the grounding pipe and a grounding pipe. A method for connecting an underground pipe by a connection structure for fixing with a bell mouth screwed to the tip of the underground pipe, wherein in the connecting structure for the underground pipe, the tightening member is a flange member and a screw. The flange member has a flange portion pressed toward the wall surface and a ring-shaped first seal member provided on the flange portion at one end portion, and the screw member is at least The inner surface has a threaded portion corresponding to the spiral corrugation of the underground buried pipe, and the threaded portion of the screw member and the underground buried pipe are screwed together with a screw having a first pitch, and the flange member Is provided with a tubular first tubular portion, the screw member is provided with a tubular second tubular portion, and one of the first tubular portion and the second tubular portion is adapted to enter the inside of the other. The first tubular portion and the second tubular portion are screwed together with a screw having a second pitch so as to be relatively rotatable around the central axis of the underground buried pipe, and the first pitch and the second tubular portion. The connection structure of the underground buried pipe is configured such that the pitches are different, and the method of connecting the underground buried pipe is such that the threaded portion of the screw member is located on the pipe center side of the underground buried pipe. Then, the step of rotating the tightening member and screwing it into the underground buried pipe, and inserting the tip of the underground buried pipe from the outside of the handhole into the through hole for piping, and inserting the bell into the tip of the inserted underground buried pipe. There is a step of screwing the mouse and a step of rotating the screw member to press the tightening member against the wall surface of the handhole. In the pressing step, the first seal member provided on the flange portion is the wall surface of the handhole. After contacting the pipe, the flange member is not rotated, only the screw member is rotated and tightened, and the wall is sandwiched between the bell mouth and the flange member from both inside and outside, and the underground buried pipe is inserted into the through hole for piping. It is a method of connecting an underground pipe, which is fixed to (1st invention).

In the first invention, it is preferable that the signs of the first pitch and the second pitch are different, and one screw is a reverse screw with respect to the other screw (second invention) .

According to the underground buried pipe connecting method (first invention) of the present invention, the relationship between the rotation of the screw member and the forward movement of the flange member at the time of the connecting operation is defined by the spiral shape of the underground buried pipe. Can be changed to another relationship, and the tightening operation at the time of connection operation can be facilitated. Further, according to the method of connecting an underground buried pipe of the present invention, it is possible to prevent insufficient sealing property between the flange member and the wall surface.

Further, according to the second invention, the tightening with the screw member can be performed quickly .

It is a partial cross section figure which shows the connection structure of the underground pipe of 1st Embodiment. It is a partial cross section figure which shows the structure of the fastening member used for the connection structure of the underground buried pipe of 1st Embodiment. It is a partial cross section figure which shows the process of the connection operation of the underground buried pipe of 1st Embodiment. It is a partial cross section figure which shows the structure of the fastening member used for the connection structure of the underground buried pipe of 2nd Embodiment.

Hereinafter, an embodiment of the invention when an underground buried pipe is connected to a wall surface of a handhole will be described with reference to the drawings. The invention is not limited to the individual embodiments described below, and the modes can be modified and implemented. The connection target of the underground buried pipe is not limited to the handhole, and may be a manhole, an information box or the like. The underground buried pipe is often used as a conduit through which a cable such as an electric wire or an optical fiber is inserted, but its specific use is not limited to these communication use and electricity supply use.

FIG. 1 is a partial cross-sectional view showing a connection structure of an underground buried pipe according to the first embodiment, and FIG. 2 is a fastening member 1 used for connection. In these drawings, the description of each member is shown in a sectional view on the upper side of the central axis m and in an external view on the lower side. Regarding the underground buried pipe 3, the entire pipe is mainly shown in an external view, and only the tip portion is shown in a partial cross section.

The underground buried pipe 3 is inserted into the piping through hole 4b provided in the wall 4 of the handhole, and the fastening member 1 screwed to the outside of the underground buried pipe 3 and the tip of the underground buried pipe 3. The bell mouth 2 which is screwed to the inner side of the part sandwiches the wall 4 so as to be connected and fixed to the hand hole. In the following description, the left side in FIGS. 1 to 4, that is, the inside of the handhole or the side facing the pipe end of the underground pipe is referred to as the “pipe end side”, and the right side in FIG. 1 to FIG. The outside of the handhole and the side facing the central portion of the underground buried pipe will be referred to as the “pipe central side”.

The underground buried pipe 3 is a flexible pipe having a bellows-shaped pipe wall in which a large diameter portion and a small diameter portion are alternately provided in the axial direction, and in particular, the large diameter portion and the small diameter portion are spirally provided. ing. That is, the underground buried pipe 3 is formed of a so-called flexible pipe with a spiral wave, and is typically formed of synthetic resin (for example, polyethylene resin). Here, the pitch of the spiral of the underground buried pipe 3 is referred to as a first pitch P1.

A bell mouth 2 is attached by screwing to the inside of the tip of the underground buried pipe 3. The bell mouth 2 has a cylindrical main body portion 21 whose outer diameter is slightly smaller than the inner diameter of the underground buried pipe 3 to be screwed, and the outer peripheral surface of the main body portion 21 has the underground buried pipe 3 The convex portion 21b, which becomes a screw thread when screwed to the, is formed in a spiral shape. A disc-shaped flange portion 21c having a through hole 21d is integrally formed on the tube end side of the body portion 21 of the bell mouth 2. If a thin donut-shaped sealing member is closely fixed to the surface of the flange portion 21c facing the wall surface of the handhole, the watertightness can be further enhanced. The seal member may be omitted as in the example of FIG. Further, the specific shape of the bell mouth 2 may be changed as long as it is possible to prevent the underground buried pipe 3 from coming out of the through hole 4b toward the center of the pipe, and the bell mouth 2 may have another configuration. Good. For example, the bell mouth may be screwed to the outside of the underground buried pipe 3.

The fastening member 1 will be described. The tightening member 1 is adapted to be screwed with the spirally corrugated outer surface of the underground buried pipe 3, and by rotating and tightening the tightening member 1 during the connecting operation, The wall 4 of the handhole is sandwiched between the fastening members 1, and the underground pipe 1 is connected and fixed to the pipe through hole 4b of the handhole.

The tightening member 1 has a flange member 11 and a screw member 12.
The flange member 11 has a flange portion 11a at one end on the pipe end side. By tightening the tightening member 1, the flange portion 11a is pressed toward the handhole wall surface 4a. Further, the flange member 11 has a ring-shaped first seal member 13, and the first seal member 13 is provided on the flange portion 11a. Further, the flange member 11 of the present embodiment has a cylindrical tubular portion 11b arranged on the outer periphery of the underground buried pipe 3.

At least the inner surface of the screw member 12 of the tightening member 1 has a screwing portion 12 a corresponding to the spiral waveform of the underground buried pipe 3. That is, the screwing portion 12a of the screw member 12 and the underground buried pipe 3 are screwed together with the screw having the first pitch P1. By rotating the screw member 12 with respect to the underground buried pipe 3, the fastening member 1 is moved forward/backward, and a connecting operation is performed. In the present embodiment, the cylindrical enlarged diameter portion 12b is provided on the pipe end side of the screwed portion 12a, and the enlarged diameter portion 12b and the screwed portion 12a are flange-shaped connection walls. It is connected by 12c. In addition, a cylindrical third seal member 15 is integrated with the inner periphery of the threaded portion 12a of the screw member 12 so as to follow the waveform.

The flange member 11 and the screw member 12 are not joined or fixed to each other, but are relatively rotatable around the central axis m of the underground buried pipe 3, and both are screwed with a screw having the second pitch P2. doing.
That is, the flange member 11 is provided with the tubular first tubular portion (11b), and the screw member 12 is provided with the tubular second tubular portion (12b), and the first tubular portion and the second tubular portion are provided. One of the two is designed so as to enter the inside of the other, and the first tubular portion and the second tubular portion are screwed together with a screw having a pitch P2. In the present embodiment, the tubular portion 11b corresponds to the first tubular portion, the expanded diameter portion 12b corresponds to the second tubular portion, and the threaded portion 11c is provided on the tubular portion 11b of the flange member. To become a male screw, and the structure is such that the male screw enters the inside of the screw member expanded portion 12b formed in a spiral waveform and is screwed together. The specific shape of the screw thread is not particularly limited.

The first pitch P1 with which the underground buried pipe 3 and the screw member 12 are screwed together is different from the second pitch P2 with which the flange member 11 and the screw member 12 are screwed together. Here, different pitches include a state in which the absolute values of the amount of advancement/retraction when the screw is rotated are different, and the direction of advancement/retraction when the screw is rotated in a predetermined direction (that is, the pitch). It also includes a state in which the sign of) is different. In the present embodiment, the signs of the first pitch and the second pitch are different, and one screw is a reverse screw with respect to the other screw. Specifically, the first-pitch screw is provided on the right-hand screw, and the second-pitch screw is provided on the left-hand screw. Further, the absolute value of the second pitch P2 is smaller than the absolute value of the first pitch P1. As in the second embodiment described later, the signs of the pitches may be the same and the absolute values of the first pitch and the second pitch may be different. Alternatively, the absolute value of the pitch may be the same, and the sign of the pitch may be different.

An annular second seal member 14 is preferably provided between the flange member 11 and the screw member 12 so as to be sandwiched in the radial direction. The second seal member may be sandwiched in the tube axis direction. In the present embodiment, the cylindrical second seal member is sandwiched in the radial direction between the first tubular portion (cylindrical portion 11b) and the second tubular portion (diameter expansion portion 12b) that are screwed together. 14 are provided. The second seal member 14 is preferably fixed to either the tubular portion 11b or the expanded diameter portion 12b, and in the present embodiment, is fixed to the outer peripheral surface of the tubular portion 11b.

As the first seal member 13, the second seal member 14, and the third seal member 15, various seal members, for example, water-swellable non-woven fabric (non-woven fabric using water-swellable resin), rubber sheet, sponge sheet, rubber Packing can be used. It is preferable to configure these sealing members so as to include the water-absorptive non-woven fabric from the viewpoints of good slippage during the connecting operation, easy tightening operation, and good sealing property. These seal members may be integrated when molding the flange member or the screw member, or may be fixed to the molded flange member or the screw member by an adhesive agent or the like in a later step.

The tightening member 1 (flange member 11 or screw member 12) or bell mouth 2 used in the connection structure of the present invention is made of synthetic resin, preferably polyolefin resin or polyvinyl chloride resin, and is used for injection molding or blow molding. It can be molded by a known molding method.

FIG. 3 is a view showing an intermediate stage of the process of completing the connection structure of the underground buried pipe of the present invention.
First, the tip of the underground buried pipe 3 made of polyethylene is cut vertically, the attached water and mud are wiped off, and the fastening member 1 is rotated and screwed so as to be screwed to the outside of the buried underground pipe 3. That is, the threaded portion 12a of the screw member 12 of the tightening member 1 is screwed so as to be positioned from the tip of the underground buried pipe 3 toward the inner side, that is, on the pipe center side. At that time, the screwing length is set to be longer than the thickness of the handhole wall 4 for fixing the underground buried pipe 3. At this time, the flange member 11 and the screw member 12 are sufficiently screwed into each other.

Next, the tip of the underground buried pipe 3 is inserted from the outside of the handhole into the through hole 4b for piping of the wall 4 of the handhole. Next, the main body portion 21 of the bell mouth 2 is screwed into the inside of the tip of the underground buried pipe 3 (intermediate state shown in FIG. 3). Then, the bell mouth 2 is screwed into the tip of the underground buried pipe 3 inserted into the through hole 4b for piping until the bell mouth flange portion 21c comes into contact with the pipe, and is firmly fixed.

Next, the fastening member 1 is pressed against the wall surface 4a of the handhole. That is, the screw member 12 of the tightening member 1 is rotated outside the handhole so that the connecting member 1 advances toward the wall surface 4a, and the flange portion 11a (sealing member 13) contacts the handhole wall surface 4a. Rotate and fasten. At this time, the flange member 11 and the screw member 12 are rotated integrally until the flange portion 11a (seal member 13) contacts the handhole wall surface 4a, but the flange portion 11a (seal member 13) does not rotate. After contacting the handhole wall surface 4a, the flange member 11 is not rotated and only the screw member 12 is rotated and tightened.
As a result, the flange portion 21c of the bell mouth 2 adheres to the wall 4 even on the inner surface of the wall 4 of the handhole, and the wall 4 is sandwiched between the bell mouth 2 and the tightening member 1 (flange member 11) from both the inner and outer surfaces thereof. In this state, the underground pipe 3 is fixed to the pipe through hole 4b provided on the wall surface of the handhole, and the connection structure as shown in FIG. 1 is completed.

In order to facilitate the tightening operation of the screw member, it is preferable to provide a rib, a flat surface portion, a notch or the like on the outer periphery of the screw member 12 with which a spanner, a wrench, a jig or the like is engaged.

The operation and effect of the invention will be described.
According to the connection structure of the above-described embodiment, the relationship between the rotation of the screw member and the forward movement of the flange member during the connection operation can be changed to a relationship different from the relationship determined by the spiral shape of the underground buried pipe. This makes it easier to tighten when connecting.

In the conventional techniques disclosed in Patent Document 1 and Patent Document 2, when the tightening member (holder) is tightened, the amount of rotation of the tightening member and the amount of advance of the tightening member are equal to those of the underground buried pipe. Related by the pitch of the spiral. Therefore, as long as existing underground pipes on the market are used, the relationship between the amount of rotation and the amount of advance is fixed. Therefore, in a certain underground buried pipe, the amount of advancement is small with respect to the amount of rotation of the fastening member, and it is necessary to rotate the fastening member many times in order to advance the fastening member by a predetermined amount. It becomes complicated. On the other hand, in another underground buried pipe, the amount of forward movement is large relative to the amount of rotation of the fastening member, and the rotational torque to be given to the fastening member in order to generate a predetermined forward force (pressing force) becomes large. Therefore, excessive force is required for connection work, and the tightening force of the connection structure becomes insufficient.

According to the connection structure of the present invention, the flange member 11 and the screw member 12 are screwed together with the screw having the second pitch P2, and the first pitch P1 and the second pitch P2 are different pitches. Therefore, the relationship between the rotation of the screw member and the forward movement of the flange member during the connection operation can be changed to a relationship different from the relationship determined by the first pitch P1 of the underground buried pipe. That is, after the flange portion 11a (seal member 13) contacts the handhole wall surface 4a, only the screw member 12 is rotated and tightened without rotating the flange member 11, but at this time, the screw The amount of advancement of the flange member 11 with respect to the underground pipe 3 when the member 12 is rotated once is P1-P2.
Therefore, with respect to the underground buried pipe (pitch P1) used, P2 is determined so that the amount of advance (P1-P2) per unit number of rotations becomes a preferable value, and the flange member 11 and the screw member 12 are configured. Then, the tightening operation of the connection operation becomes easy.

For example, in the underground buried pipe connection structure of the first embodiment described above, the first pitch P1 and the second pitch P2 have different signs, and the screw to which the flange member 11 and the screw member 12 are screwed is buried underground. The tube 3 and the screw member 12 are reverse threads to the threads that are screwed together. However, in the case of such a reverse thread configuration, the amount of advance (P1-P2) per unit rotation speed is The pitch can be made larger than the pitch P1 of the middle buried pipe, and the tightening of the tightening member 1 can be achieved with a smaller number of rotations, and the tightening operation becomes easier. Especially when tightening the tightening member with a wrench, wrench, etc., the tightening operation tends to be complicated, so if such a reverse screw configuration is adopted, the tightening work can be performed particularly quickly. Therefore, the workability of the connection operation is improved.

Further, when the annular second seal member 14 is provided so as to be sandwiched in the radial direction between the flange member 11 and the screw member 12 as in the first embodiment, the second seal member is used. It is possible to prevent the relative rotation between the screw member 12 and the flange member 11 from being hindered by the frictional force of the screw member 14, and the tightening operation of the screw member 12 becomes easier.

When the seal member 14 provided between the screw member 12 and the flange member 11 contains a water-absorptive non-woven fabric as in the first embodiment, the frictional force between the seal member 14 and other members is increased. Is further reduced, and the tightening operation of the screw member becomes easier.

Further, according to the underground buried pipe connecting structure as in the first embodiment, the flange member 11 and the screw member 12 forming the tightening member 1 are relatively rotatable with respect to each other around the central axis of the underground buried pipe. Therefore, after the first seal member 13 comes into contact with the handhole wall surface 4a, the screwing operation can be performed by rotating only the screw member 12 without rotating the flange member 11. This prevents the first seal member 13 from being rubbed against the wall surface 4a of the handhole and being damaged or peeled off, resulting in insufficient sealing performance.

The invention is not limited to the above-described embodiment, but can be implemented with various modifications. Other embodiments of the invention will be described below, but in the following description, portions different from the above-described embodiment will be mainly described, and detailed description of the same portions will be omitted. Moreover, these embodiments can be implemented by combining some of them with each other or by replacing some of them.

In the above description of the first embodiment, the example in which the seal member 14 is attached to the outside of the tubular portion 11b of the flange member 11 has been described, but the seal member 14 is attached to the inner circumference of the expanded diameter portion 12b of the screw member 12. It may be attached. It is also possible to reverse the relationship between the inside and outside of the tubular portion 11b of the flange member 11 and the expanded diameter portion 12b of the screw member 12. That is, as long as the screw member and the flange member can be rotated relative to each other and the screw member and the flange member are screwed with each other, the specific configuration and structure of the portion where the screw member and the flange member are screwed, the arrangement of the seal member, and the like can be appropriately changed. ..

FIG. 4 is a partial cross-sectional view showing the structure of the fastening member 5 used for the connection structure of the underground buried pipe of the second embodiment. In the present embodiment, the flange member 51 has the flange portion 51a and the ring-shaped first seal member 53 on the pipe end side, and the screw member 52 is the screw portion 52a and the cylindrical third seal member 55. A point that is screwed into a spiral shape having a first pitch P1 on the outer circumference of the underground buried pipe, a first tubular portion 51b of the flange member 51, and a second tubular portion 52b of the screw member 52. Are relatively rotatable about the central axis and are screwed to each other at the second pitch P2, as in the first embodiment. Also in this embodiment, the tightening operation at the time of the connection operation becomes easy.

In the second embodiment, the first pitch P1 with which the underground buried pipe and the screw member 52 are screwed together and the second pitch P2 with which the flange member 51 and the screw member 52 are screwed together are the pitch P1 and the pitch P2. Have the same sign, and the absolute value of the second pitch P2 is smaller than the absolute value of the first pitch P1. Specifically, both the first pitch screw and the second pitch screw are right-hand screws, and the second pitch P2 is about half the size of the first pitch P1.

If the relationship between the first pitch P1 and the second pitch P2 is set in this way, the amount of advance of the flange member 51 with respect to the underground buried pipe (P1- P2) becomes smaller than the first pitch P1. Therefore, the amount of advancement of the flange member when the screw member is rotated is reduced, and the rotational torque required for tightening operation can be reduced. In such an embodiment, when the pitch of the underground pipes (first pitch P1) is relatively large and the tightening operation force is likely to be excessive, the tightening torque can be reduced and the tightening operation can be facilitated. ..

Further, in the second embodiment, the cylindrical third tubular portion 51c is provided between the flange portion 51a of the flange member 51 and the tubular portion 51b screwed with the screw, and the corresponding screw member 52 is provided. Is provided with a cylindrical fourth cylindrical portion 52c on the pipe end side. Then, the second seal member 54 is provided in a cylindrical shape so as to be sandwiched in the radial direction between the third tubular portion 51c and the fourth tubular portion 52c. As in the present embodiment, the second seal member may be provided in a portion other than the screwed portion.

Further, like the tightening member 5 of the second embodiment, a portion of the second tubular portion 52b of the screw member 52 formed in a bellows shape with a spiral wave is a screw of the first tubular portion 51b of the flange member 51. It is preferable that a bellows-shaped portion that is formed longer than the portion that is screwed with and that is not directly involved in screwing the screw with the second pitch is provided on the tube center side of the second tubular portion 52b. .. When such a bellows-shaped section is provided, when the screw member 52 is tightened, the bellows-shaped section can be elastically deformed so as to contract, and the expansion and contraction of this section absorbs the displacement and inclination of the pipe in the central axis direction. Therefore, the first seal member can be elastically pressed down, and the reliability of the sealability of the connection structure is improved. Note that the specific configuration of such a bellows-like section is not limited to the form in which the thread portion of the second pitch is formed to be extended, and may be, for example, a shape with a plurality of ring-shaped uneven waves. .. Further, in the screw member 12 of the tightening member 1 of the first embodiment described above, for example, a similar bellows-shaped section may be provided between the second tubular portion 12b and the connection wall 12c.

In the description of the above embodiments, the underground buried pipe is used as a conduit for inserting an optical fiber cable for information communication, an electric cable for power transmission, an electric wire for communication, etc. as an example. Although the connection structure of the pipe has been described, the application of the underground buried pipe is not limited to these applications, other applications, for example, for sending gas or liquid, for inserting and arranging piping such as various hoses and tubes. It can also be used.

INDUSTRIAL APPLICABILITY The underground buried pipe connection structure of the present invention can be used, for example, for laying communication cables, is easy to construct, has a good sealing property, and has a high industrial utility value.

1 Tightening member 11 Flange member 11a Flange portion 11b Cylindrical portion (first tubular portion)
12 screw member 12a screwing portion 12b expanded diameter portion (second tubular portion)
12c Connection wall 13 First seal member 14 Second seal member 15 Third seal member 2 Bell mouth 3 Underground pipe 4 Handhole wall 5 Tightening member 51 Flange member 52 Screw member

Claims (2)

In the through hole for piping provided in the wall surface of the handhole, etc., the underground buried pipe consisting of a flexible pipe with a spiral wave is tightened to the outside of the underground buried pipe and the tip of the underground buried pipe. A method of connecting underground pipes by a connection structure that is fixed with a bell mouth screwed to
In the connection structure of the underground pipe,
The tightening member has a flange member and a screw member,
The flange member has a flange portion pressed toward the wall surface and a ring-shaped first seal member provided on the flange portion at one end portion thereof,
At least the inner surface of the screw member has a screwing portion corresponding to the spiral waveform of the underground buried pipe, and the screwing portion of the screw member and the underground buried pipe are screwed with a screw having a first pitch,
In addition, the flange member is provided with a tubular first tubular portion, and the screw member is provided with a tubular second tubular portion, and one of the first tubular portion and the second tubular portion enters inside the other. Being done,
The first tubular portion and the second tubular portion are screwed with a screw having a second pitch so as to be relatively rotatable around the central axis of the underground buried pipe,
The underground buried pipe connection structure is configured such that the first pitch and the second pitch are different pitches ,
The connection method of the underground pipe is
A step of rotating the fastening member and screwing it into the underground buried pipe so that the threaded portion of the screw member is located on the pipe center side of the underground buried pipe;
Inserting the tip of the underground buried pipe into the through hole for piping from the outside of the handhole, and screwing a bell mouth to the tip of the inserted underground buried pipe,
There is a step of rotating the screw member and pressing the tightening member against the wall surface of the handhole,
In the pressure contact step,
After the first seal member provided on the flange portion comes into contact with the wall surface of the handhole, the flange member is not rotated, but only the screw member is rotated and tightened,
With the wall sandwiched from both inside and outside by the bell mouth and the flange member, the underground buried pipe is fixed to the through hole for piping,
How to connect underground pipes . The method for connecting a buried underground pipe according to claim 1, wherein in the connection structure, the first pitch and the second pitch have different signs, and one screw is a reverse screw with respect to the other screw .

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