JPH11166678A - Connecting method for piping and connecting structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a connecting part from slipping out or piping itself from being damaged in case of an earthquake by allowing pulling-out of the prescribed length by rupturing or deforming a part of a separation preventive means when separating force between adjacent piping exceeds a preset level. SOLUTION: A separation preventive means A1 is composed of retaining rings 5 and 5 hookingly fastened to annular projecting parts 2 and 3 of piping 50 and 50 and plural connecting wire rods 6 straddlingly arranged in parallel at prescribed intervals between both retaining rings. In the respective connecting wire rods 6, the length is set to a dimension capable of preventing the other inserting/fitting end from being completely pulled out of a diametrically expanded part 1 of the piping 50. In an ordinary connecting state, the connecting wire rods 6 are put in a tensile state by forming a contracting plate (a) as a coil winding, and are embedded in a covering block 7 composed of a synthetic resin. When exceeding a preset level since separating force acts on a connecting place of the piping, the contracting place (a) is instantly drawn out so that the inserting/fitting end of the piping 50 is pulled out by an extended quantity from the diametrically expanding part 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a so-called "floating" method in the case where the ground fluctuates due to an earthquake, local collapse of the ground, or the like.
Damage to the piping itself and pipe joints, such as water and sewer pipes buried underground called lifelines, raw material pipes laid around chemical factories, and oil supply pipes laid on the ground in oil producing areas. The present invention relates to a pipe connecting method and a pipe connecting method that can almost certainly prevent the damage and prevent further expansion of a disaster due to a large amount of leakage of clean water, sewage, and various dangerous industrial materials and oils.

[0002]

2. Description of the Related Art For example, a currently used drain pipe made of vinyl chloride is configured such that an insertion end of an adjacent pipe to be connected is inserted into an enlarged diameter portion provided at one end thereof. . Then, a water stop packing is fitted in a gap formed on the inner peripheral surface of the enlarged diameter portion.

[0003]

However, according to the above-described simple pipe connection structure, when the ground moves due to the occurrence of a large-scale earthquake or the local collapse of the ground due to some special circumstances, the adjacent pipe connection structure is not provided. In many cases, a force acting to separate the pipes from each other is generated, and the connection points of the pipes are disconnected or the pipes themselves are damaged.

[0004] In such a case, a large amount of dirty sewage in the case of a sewer and a large amount of precious water in the case of a water supply penetrate into the ground, causing a secondary disaster. In addition, repairing or replacing pipes that have been dislodged or damaged underground takes a great deal of effort and time, and prolongs the confusion in the event of an earthquake. And, of course, the extra expenditures increase. On the other hand, if the raw material pipes, oil supply pipes and the like of the chemical factory are damaged, a more serious dangerous situation will be caused. Therefore, an object of the present invention is to provide a pipe connecting method and a pipe connecting method which can almost eliminate the possibility that a pipe connecting point is disconnected or the pipe itself is damaged even if the ground fluctuates due to a strong earthquake or the like. In creating the structure.

[0005]

In order to achieve the above-mentioned object, a pipe connecting method according to the present invention is provided with an enlarged portion having a predetermined length at one end of a pipe, into which the other pipe end is inserted. When the force to separate adjacent pipes from each other is exerted due to the movement of the ground due to the occurrence of an earthquake, the insertion end of the other pipe is pulled out from the enlarged diameter part of one pipe. In order to prevent the separation force, the separation force provided with the connection and separation prevention function of the pipe is laid between the annular projections provided on the outer peripheral surfaces of the both ends of the pipe. When the set level is exceeded, a part of the separation preventing means is broken or deformed to allow the drawing-out by a predetermined length. It is preferable that the separation preventing means includes a member that attenuates the detachment force exerted on the pipe by being broken or deformed by receiving the detachment force equal to or higher than the set level.

Further, the pipe connecting structure according to the present invention is a pipe connecting structure in which one pipe end is provided with a predetermined-diameter enlarged portion into which the other pipe end is inserted. When a force that separates adjacent pipes from each other acts due to ground movement, etc., when this separation force exceeds a set level,
Separation prevention means having a pipe connection and separation prevention function for preventing the insertion end of the other pipe from being pulled out from the enlarged diameter portion of one adjacent pipe is provided. Is a set of locking members hooked on each of the annular projections provided at both ends of the pipe, and a plurality of connecting wires or connecting strips laid in parallel between the locking members. The connecting wire rod is set to a length that can prevent the pull-out, and the middle portion thereof is wound with a coil or the like to form a contracted portion, and the contracted portion is formed of a coating block made of a synthetic resin or an elastomer. It is characterized in that when it is buried inside and receives a separating force equal to or higher than the set level, the covering block undergoes deformation such as breaking or stretching. The separation preventing means includes a pair of locking members hooked between the two annular projections adjacent to each other at a connection point of the pipe, and a plurality of strips laid in parallel between the locking members. A connecting wire or a connecting band is provided, and the plurality of connecting wires or a part of the connecting band have a length that can be laid in a tension state between the locking members and a weaker tensile strength. Provided, the remaining connection wire having a higher tensile strength is provided with a shrinking portion provided by winding a middle portion of the connection wire by coiling or the like, and when subjected to a separation force equal to or higher than the set level, the connection portion is connected. The wire may be configured to break or stretch. Further, the separation preventing means includes a fastening bolt inserted into a bolt hole of the annular protrusion formed in a flange shape at both ends of the pipe, and is screwed to an intermediate portion of the fastening bolt, and the two bolts are connected at a connecting point of the pipe. A fastening nut that pulls the annular protrusions together; and a lock nut screwed to the tip of the fastening bolt, the strength characteristics of the fastening nut being destroyed by a separation force equal to or higher than the set level. It is good to set it as follows. And
The fastening nut is made of a synthetic resin made to be broken by receiving a separating force equal to or higher than the set level. A cut or a notch may be provided on the surface. Alternatively, the fastening nut may have a configuration in which an inner peripheral layer made of a synthetic resin or an elastomer having elasticity is fitted to an inner peripheral surface of an outer peripheral layer made of a rigid material. Further, as another embodiment, as a pipe connection structure, an annular projection is formed and placed on each of the inner peripheral surface at the distal end of the enlarged diameter portion and the outer peripheral surface at the other end of the pipe, and the occurrence of an earthquake, etc. Due to the movement of the ground caused by the movement of the ground, when the force to separate the adjacent pipes from each other acts, the annular projections interfere with each other, and the insertion end of the other pipe is pulled out from the enlarged diameter part of one pipe. May be prevented. A cushioning material may be provided in the cylindrical gap generated between the annular projections.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described.
This will be described with reference to FIGS. The pipe 50 of this embodiment is a drain pipe made of hard vinyl chloride, and one pipe end is connected to the other pipe end of the adjacent pipe 50 to be connected (hereinafter, referred to as a pipe).
(Referred to as an insertion end) is provided with a large-diameter portion 1 having a predetermined length. The stepped portion at the base end of the enlarged diameter portion 1 is an annular projection 2. On the inner peripheral surface at the tip of the enlarged diameter portion 1,
The packing 4 for stopping water is fixed.

As shown on the right side of FIG. 1, the enlarged diameter portion 1 is inserted into the insertion end of the pipe 50 in a state where it is completely inserted into the enlarged diameter portion 1.
An annular projection 3 is provided on the outer peripheral surface at a position slightly separated from the tip of the rim. The annular projection 3 of this embodiment is formed by cutting the pipe 50 into a circle and cutting one portion in the circumferential direction.
This is formed in such a manner that it is externally fitted to a predetermined portion of the pipe 50 in an expanded state, and then fixed with an adhesive dedicated to PVC.

[0009] When a force for separating the adjacent pipes 50 from each other acts on the ground due to the movement of the ground due to the occurrence of an earthquake or the like, it operates when the separation force exceeds a set level, and the adjacent pipes 50, 50 are adjacent to each other. In order to prevent the insertion end of one pipe 50 from being completely pulled out from the enlarged-diameter portion 1 of the other pipe 50, the separation preventing means A 1, which also serves as a connecting tool for the pipes, is provided with two annular rings. Assembled so as to straddle between the protrusions 2 and 3.

The separation preventing means A1 of this embodiment is similar to that of FIG.
As shown in FIG. 3, a pair of retaining rings (locking members) 5 and 5 which are respectively engaged with the annular projections 2 and 3 of both pipes 50 and 50 to be connected, and both retaining rings 5 and 5 It comprises a plurality of, in this case, six, connecting wires 6 laid in parallel at a predetermined interval therebetween. A strip may be used in place of the wire.
The retaining ring 5 and the connecting wire 6 of this embodiment are made of stainless steel.

As shown in FIG. 4, the length of each connecting wire 6 is such that when the above-mentioned separating force F is applied, two adjacent pipes 50 are inserted from one enlarged diameter portion 1 to the other. The dimensions are set so as to prevent the fitting end from being completely pulled out. As shown in FIG. 3, the middle portion of the connecting wire 6 forms a contracted portion a by winding a coil or the like, so that the connecting wire 6 is connected in a normal pipe connection state shown in FIG. 1. , Is reduced to a size that can be stretched in a tension state between a pair of retaining rings 5 and 5.

Further, the shrinking portion a is embedded in a covering block 7 made of a synthetic resin or an elastomer to fix the shrinking state. When the above-mentioned separation force F generated by the movement of the ground due to the occurrence of an earthquake or the like exceeds a set level, the material and the size of the covering block 7 are changed so as to break as shown in FIGS. The shape and the like are selected based on test results by trial and error.

In order to fix both ends of the connecting wire 6 to both the retaining rings 5 and 5, respectively, for example, as shown in FIGS. What is necessary is just to hook both ends of the wire 6 on each retaining ring 5 in the form of a loop, and then wind a known clasp 8 for caulking around the loop end to perform caulking.

Next, the operation of the above configuration will be described. Piping 5
0, the adjacent pipes 50 and 5 are buried as shown in FIG.
The state where one of the insertion ends 0 is completely inserted into the other enlarged-diameter portion 1 is fixed by separation preventing means A1 having a configuration schematically shown in FIG. Although the illustrated retaining ring 5 is seamless, a retaining ring having a configuration in which bolts and nuts or connecting portions fastened by caulking means are provided at both ends of a cut provided at one location in the circumferential direction is used. You may.

After the laying of the pipe 50, a buried ground of the pipe moves due to a large earthquake, a sudden collapse of the ground for some reason, or the like. May act as a separating force to separate the pipes from each other at the connection point.

In this case, a strong tensile force is naturally exerted on each connecting wire 6. Then, as shown in FIG. 4, when the separating force F exceeds a set level, the coiled contracted portion a in the middle of the connecting wire 6 is almost instantaneously stretched. Along with this, the covering block 7 made of a synthetic resin or an elastomer, which has wrapped around the shrinkage point a, is torn off as shown in the figure or stretched together with the connecting wire 6.

As a result, since the connecting wire 6 is completely extended, the insertion end of one adjacent pipe 50 is
The two pipes 50, 50 can be made to follow the movement of the ground by being pulled out from the enlarged diameter portion 1 of the other pipe 50 by an amount corresponding to the extension of the connecting wire 6. Even when the separating force F acts in an impact manner, the strong impact force is applied to the covering block 7.
Is effectively attenuated by the amount of time spent breaking or stretching the wire. Therefore, it is possible to prevent the pipe 50 itself from being broken due to an excessive tensile force or shearing force applied to the two pipes 50, 50.

Then, as shown in FIG. 4, when the completely extended connecting wire 6 is in a state of preventing further separation of the adjacent pipes 50, 50, the two pipes 50, 50
The length of the connecting wires 6 is set in advance so as to be maintained in a connected state. Therefore, even if sudden ground fluctuation occurs, it is not necessary to cause a situation in which a connecting portion of the pipe is disconnected. Even when the ground fluctuates over a fairly wide range, each of the pipe connection points behaves as described above, so that the pipe group can sufficiently follow this wide ground movement.

FIGS. 6 and 7 show a separation preventing means A2 as a second embodiment. This separation preventing means A
Reference numeral 2 denotes a first connection strip having a length capable of being stretched between a pair of retaining rings 5 and 5 and a relatively weak tensile strength in a normal connection state of the pipe 50 (see FIG. 1). 6A and a plurality of second connecting wires 6B each having a predetermined length and a high tensile strength, like the connecting wires 6 of the first embodiment.

The first connecting strip 6A of this embodiment is a synthetic resin band reinforced with a synthetic fiber strip. Alternatively, a rod made of an elastomer or a synthetic resin may be used. The second connecting wire 6B is folded in the middle part as shown in the drawing to form a contracted portion a, and this portion is wrapped with the cover member 9 to fix the contracted state. As the cover member 9, a synthetic resin tube or the like may be used. The cover member 9 is not essential, and may be omitted.

Each of the plurality of connecting strips 6A and connecting wires 6B
Are alternately bridged in parallel at a predetermined interval between a pair of retaining rings 5, 5, as shown. Reference numeral 10 denotes a stopper similar to the stopper 8.

As shown in FIG. 7, the action of the separation preventing means A2 is such that the ground fluctuates due to a large-scale earthquake or sudden collapse of the ground, and a separation force F equal to or higher than a set level is applied to a connecting portion of the pipes. When actuated, the connecting strip 6A breaks or stretches, attenuating the strong separating force F exerted at that time.

Then, a strong tensile force acts on the connecting wire 6B in accordance with the breakage of the connecting band 6A, so that when the cover member 9 is provided, it is cut off as shown in the drawing. The wire 6B is completely extended. As a result, as in the first embodiment, the pipe 50 follows the movement of the ground to some extent, and the impact separation force is attenuated. I can definitely escape.

Next, FIGS. 8 and 9 show the separation preventing means A3 of the third embodiment. The separation preventing means A3 of this embodiment is characterized by the structure of the connecting wire 6. That is, the first connecting wire 6C having a sufficiently high tensile strength and having a shrinkage point a at an intermediate portion thereof is connected to the two pipes 5 in a normal connecting state.
Each of the plurality of second connecting wires 6D having a length that can be stretched between a set of retaining rings 5 and 0 and that is broken by receiving a separating force equal to or more than a set level, As shown in the drawing, the retaining rings 5 and 5 are alternately provided between the pair of retaining rings 5 and 5. The operation of the separation preventing means A3 is the same as that of the separation preventing means A2, and thus the description is omitted.

Next, FIGS. 10 and 11 show the separation preventing means A4 of the fourth embodiment. This separation preventing means A4
Also, the configuration of the connecting wire 6 is characterized. In other words, each of the plurality of connecting wires 6 has a sufficiently high tensile strength, and has a shrinking portion at a middle portion thereof in a state where the connecting wire 6 is laid between the pair of retaining rings 5 and 5, in this case, a slack portion a occurs. One connecting wire 6E and, as described above, a second connecting wire 6F that has a length that can be stretched between the pair of retaining rings 5 and 5 and that breaks upon receiving a separating force equal to or higher than a set level. Are fixed to the retaining ring 5 in a state where both ends are bundled. The operation of the separation preventing means A4 is similar to that of the separation preventing means A2.

FIGS. 12 and 13 show a separation preventing means A5 according to a fifth embodiment of the present invention. Separation prevention means A5
Is attached to the tip of the enlarged diameter portion 1 of one pipe 50 to be connected.
First locking ring (annular protrusion) 11 fixed in an internally fitted state
And a second locking ring (annular protruding portion) 12 which is fixed to the tip end of the insertion end of the other pipe 50 in an externally fitted state.

The pipe 50 in this case is also made of hard vinyl chloride, and the first and second locking rings 11 and 12 are provided in the same manner as the annular projection 3 of the first embodiment. 13 is a packing for stopping water.

As shown in FIG. 12, a cushioning member 14 is provided in a cylindrical space b formed between the locking rings 11 and 12. The cushioning material 14 of this embodiment is formed in a cylindrical shape, and is made of a rubber sponge having a relatively low expansion ratio. The outer peripheral surface is provided with unevenness for leaving room for compression deformation.

The operation of the separation preventing means A5 is apparent in the figure, and is initially in the state shown in FIG. 12 when the pipe 50 is buried. However, the buried ground fluctuates and receives a separation force F equal to or higher than the set level. The two pipes 50, 50 behave as shown in FIG. At that time, as the volume of the cylindrical gap b decreases, the shock-absorbing force is reliably attenuated by the compression of the cushioning material 14.

14 to 17 show a separation preventing means A6 according to a sixth embodiment in which the present invention is applied to a water supply pipe. Bolt holes (not shown) are provided at a plurality of positions in the circumferential direction on the flange-shaped annular protrusion 21 formed at the end of the enlarged diameter portion 1 of the pipe 51 of this embodiment. Further, on the insertion end side of the pipe 51, in a state where the insertion end is completely inserted into the enlarged diameter portion 1, an annular projection 21 is formed on the outer peripheral surface at a position slightly separated from the enlarged diameter portion 1. A pair of flange-shaped annular projections 22 are attached. 23 is a gasket sandwiched between the two annular projections 21 and 22, and 24 is a packing.

The separation preventing means A6 includes a plurality of fastening bolts 25 respectively inserted into bolt holes provided at a plurality of locations of the opposed annular projections 21 and 22, and a plurality of fastening bolts 25.
And a locking nut 27 screwed to the tip of the fastening bolt 25.

As shown in FIG. 14, the length of the fastening bolt 25 is longer than that required for fastening the two annular projections 21 and 22 via the gasket 23 by a predetermined dimension.

The fastening nut 26A, which plays a role of pulling the two annular projections 21 and 22 toward each other, is used when the force to separate the adjacent pipes 51 from each other acts on the ground due to the movement of the ground due to an earthquake or the like. The strength characteristics are set so that the sheet breaks when it receives a separation force F equal to or higher than a set level. The fastening nut 26A of this embodiment is made of a synthetic resin.

As is easily understood from FIGS. 14 and 15, the action of the separation preventing means A6 is such that when the separation force F exerted on the two pipes 51, 51 due to the fluctuation of the ground exceeds a set level. The synthetic resin fastening nut 26A is broken. For this reason, along with this destruction, the impulsive separation force F is attenuated, and the two pipes 51, 51 are allowed to displace following the movement of the ground, so that the damage can be reliably prevented. I can do it.

As shown in FIG. 15, when the two pipes 51 are gradually separated from each other and the annular projection 22 comes into contact with the lock nut 27, the lock nut 27 prevents further separation. This eliminates the need for the insertion end of one pipe 51 to be pulled out from the enlarged diameter portion 1 of the other pipe 51.

FIG. 16 shows a second embodiment of the fastening nut 2. A feature of the fastening nut 26B is that a cut c is provided on the outer peripheral surface thereof so that the fastening nut 26B is broken by receiving a separating force F equal to or higher than the set level.

FIG. 17 shows a third embodiment of the fastening nut. The fastening nut 26C has a structure in which an inner peripheral layer 29 made of a synthetic resin or an elastomer having elasticity is fitted to the inner peripheral surface of an outer peripheral layer 28 made of a rigid material.

The function of the fastening nut 26C is to lose its function because the inner peripheral layer 29 is deformed and pulled out of the outer peripheral layer 28 when it receives a separation force F equal to or higher than the above-mentioned set level. .

FIG. 18 shows a fourth embodiment of the fastening nut. The fastening nut 26D of this embodiment has a form in which a metal tube 31 is placed over the outer peripheral surface of a split nut 30 divided along the radial direction and fixed by caulking. When the metal tube 31 is subjected to a separation force F equal to or higher than the set level, the metal tube 31 breaks and the fastening nut 26
D is broken.

Although the pipes 50 and 51 in the above embodiments are made of synthetic resin or metal, they may be fume pipes or earth pipes. And pipes are, of course, not limited to sewer pipes and water pipes. For example, various raw material pipes laid on the floor of a chemical plant or on the ground of a site, and oil supply pipes laid endlessly in an oil producing area The present invention can be applied to the above. The material and shape of each member constituting the separation preventing means A1 to A6 may be appropriately selected so as to be most suitable for each of various pipes having different shapes, materials, pipe diameters, and the like.

[0041]

As is apparent from the above description, according to the pipe connection method and connection structure of the present invention, the following practically excellent effects can be obtained. (A) When the ground moves due to the occurrence of an earthquake or a local depression of the ground, etc., and a force acts to separate adjacent pipes from each other, if the separating force exceeds a set level, the separation preventing means operates. Although a certain degree of separation is allowed, it is possible to completely prevent the pipe connection portion from being completely disconnected. (B) When a part of the components of the separation preventing means is broken or deformed due to the separating force exerted by impact,
It also plays a role in attenuating this powerful force, coupled with the fact that the pipes can follow the ground movement to some extent,
The possibility that the pipe itself is destroyed can be almost certainly eliminated. (C) Therefore, when a large earthquake occurs, a large amount of tap water or sewage leaks from the water supply pipe or the sewer pipe, and the confusion can be prevented from becoming more serious. (D) If the pipe is a raw material pipe of a chemical plant or an oil feed pipe laid in an oil-producing area, it is possible to prevent a serious situation caused by a large amount of leakage of chemical raw materials and oils.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of the present invention, and is a longitudinal sectional view of a pipe connection portion when a pipe is laid.

FIG. 2 is a perspective view schematically showing a form of a separation preventing unit in a state where the unit is attached to a pipe.

FIG. 3 is a partially cutaway side view of the separation prevention unit.

Fig. 4 Same as above, when the ground moves due to an earthquake, etc.
It is a partial longitudinal section of a pipe connection place.

Fig. 5 Same as above, when the ground moves due to an earthquake
It is operation | movement explanatory drawing of a separation prevention means.

FIG. 6 is a side view showing the separation preventing means of the second embodiment and showing a state at the time of laying a pipe.

Fig. 7 Same as above, when the ground moves due to an earthquake
It is operation | movement explanatory drawing of a separation prevention means.

FIG. 8 is a perspective view showing the separation preventing means of the third embodiment and showing a state at the time of laying a pipe.

[Fig. 9] As above, when the ground moves due to an earthquake or the like,
It is operation | movement explanatory drawing of a separation prevention means.

FIG. 10 is a partial side view showing a state in which a pipe is laid, showing a separation preventing means of the fourth embodiment.

FIG. 11 is a diagram illustrating the operation of the separation preventing means when the ground moves due to an earthquake or the like.

FIG. 12 is a vertical cross-sectional view of a pipe connection portion when a pipe is laid, showing the separation preventing means of the fifth embodiment.

FIG. 13 is an explanatory view of the operation of the separation preventing means when the ground moves due to an earthquake or the like.

FIG. 14 is a vertical cross-sectional view of a pipe connection portion when a pipe is laid, showing the separation preventing means of the sixth embodiment.

FIG. 15 is an explanatory diagram of the operation of the separation preventing means when the ground moves due to an earthquake or the like.

FIG. 16 is a perspective view of the fastening nut of the second embodiment.

FIG. 17 is a longitudinal sectional view of the fastening nut of the third embodiment.

FIG. 18 is a perspective view and a longitudinal sectional view of the fastening nut of the fourth embodiment.

[Explanation of symbols]

 A1 to A6 Separation preventing means 1 Large diameter portion 2, 3 Annular protrusion 4 Packing 5 Retaining ring (locking member) 6, 6A to 6F Connecting wire (band) material 7 Coating block 8, 10 Clasp 9 Cover member 11 1 locking ring (annular projection) 12 second locking ring (annular projection) 13 packing 14 cushioning material 21, 22 annular projection 23 gasket 24 packing 25 fastening bolt 26A-26D fastening nut 27 stop nut 28 outer peripheral layer 29 Inner peripheral layer 30 Split nut 31 Metal tube 50, 51 Piping a Shrinkage point b Cylindrical void c Cut

Claims (10)

[Claims] 1. A method of connecting pipes in which one pipe end is provided with an enlarged diameter portion having a predetermined length into which the other pipe end is inserted, wherein adjacent pipes are connected to each other by movement of the ground due to an earthquake. In order to prevent the inserted end of the other pipe from being pulled out from the enlarged diameter part of one pipe when a force is exerted to separate the pipes from each other, annular projections provided on the respective outer peripheral surfaces at both ends of the pipe are provided. In the meantime, a separation prevention means having a pipe connection and separation prevention function is laid so as to straddle it, and when the separation force exceeds a set level, a part of the separation prevention means is broken or deformed to a predetermined length. A method of connecting pipes, wherein the drawer is only allowed. 2. The method according to claim 1, wherein the separation preventing unit receives a separating force equal to or higher than the set level and breaks or deforms.
The method of connecting pipes according to claim 1, further comprising a member that attenuates the separation force exerted on the pipes by impact. 3. A pipe connection structure in which one pipe end is provided with an enlarged diameter portion having a predetermined length into which the other pipe end is inserted, and adjacent pipes are connected to each other by movement of the ground due to an earthquake. When a force is applied to separate the pipes from each other, when the separation force exceeds a set level, the insertion end of the other pipe is prevented from being pulled out from the expanded portion of the adjacent one pipe, Separation preventing means having a function of connecting and separating pipes is provided, and the separation preventing means includes a set of locking members hooked on respective annular projections provided at both ends of the pipe; A plurality of connecting wires or connecting strips straddled in parallel between the locking members, and the connecting wire set to a length that can prevent the pull-out is formed by coiling an intermediate portion thereof. To form a shrinking part, and to make the shrinking part A pipe connection characterized in that, when embedded and placed in a covering block made of a stoma and subjected to a separating force equal to or higher than the set level, the covering block is deformed such as breaking or stretching. Construction. 4. The separation preventing means comprises: a pair of locking members locked between adjacent annular projections at a connecting point of a pipe, and straddling in parallel between the locking members. A plurality of connecting wires or connecting strips, and a part of the plurality of connecting wires or connecting strips can be stretched in a tension state between the locking members, and The connection wire having a low tensile strength and the remaining portion having a higher tensile strength is provided with a shrinkage portion provided by winding a middle portion of the connection wire by coil winding or the like, and receives a separation force equal to or higher than the set level. 4. The pipe connection structure according to claim 3, wherein the connection wires are configured to be broken or stretched. 5. The separation preventing means comprises: a fastening bolt inserted into a bolt hole of the annular projection formed in a flange shape at both ends of the pipe; A fastening nut that pulls the two annular projections toward each other, and a lock nut screwed to the tip of the fastening bolt.The strength characteristics of the fastening nut are destroyed by receiving a separation force equal to or higher than the set level. 4. The pipe connection structure according to claim 3, wherein the pipe connection structure is set so as to be set to a predetermined value. 6. The piping connection structure according to claim 5, wherein the fastening nut is made of a synthetic resin and is made to break when subjected to a separation force equal to or higher than the set level. 7. The piping according to claim 5, wherein the fastening nut is provided with a cut or a notch on an outer peripheral surface thereof so as to be broken by receiving a separating force of the set level or more. Connection structure. 8. The fastening nut has a structure in which an inner peripheral layer made of a synthetic resin or an elastomer having elasticity is fitted to an inner peripheral surface of an outer peripheral layer made of a rigid material. 6. The connection structure of the pipe according to 5. 9. A connection structure for pipes, wherein one end of a pipe is provided with a large-diameter portion having a predetermined length into which the other pipe end is inserted. An annular protrusion is formed on each of the outer peripheral surfaces of the pipe ends, and the two annular protrusions are separated from each other when a force is exerted to separate adjacent pipes from each other with the movement of the ground due to an earthquake or the like. A pipe connection structure which interferes with each other and prevents the insertion end of the other pipe from being pulled out from the enlarged diameter portion of one pipe. 10. A cushioning material is provided in a cylindrical gap formed between said annular projections.
The connection structure of the piping described.