JP3992791B2 - Pipe high-strength connection method and connection device - Google Patents

Description

【００２３】
【発明の効果】
以上説明したように、本発明に係る接続方法によれば、鉄系形状記憶合金製パイプ用継手を用いてパイプを接続するにあたり、継手の収縮力による締結力に加えてＣ形リングのごとき機械的な締結力を付与し得るため、より引き抜き強度の高い接続を達成することができる。従って、パイプを構造体として残すようなパイプの接続手段として、特に曲線ボーリング工法に適用する接続手段として最適なものといえる。また、樹脂系シール剤を併用する場合には、より一層継手強度を高めると共に、優れたシール性も発揮するため、特に、シール性の要求される接続部に適用して効果的である。
【図面の簡単な説明】
【図１】本発明に係る接続手段の一実施例を示す部分断面図。
【図２】（ａ）は図１における手段にて締結されたパイプ接続部の断面図、（ｂ）はＣ形リングの斜視図。
【図３】（ａ）は図２のＡ−Ａ線断面図、（ｂ）は図２のＢ−Ｂ線断面図。
【図４】図１の別の実施形態例を示す断面図。
【符号の説明】
１ パイプ
２ 形状記憶合金製パイプ用円筒継手
３，１３．２３ パイプ側の溝
４，２４ 継手側の溝
５，１５，２５ Ｃ形リング
６ シール剤[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a high-strength connection method for pipes , and more particularly, to a high-strength connection method for arc-shaped curved pipes used as support structures in the ground .
[0002]
[Prior art]
When constructing or constructing a new tunnel or underground structure, in order to excavate the soil and prevent the inner wall of this excavated part from being crushed by earth pressure, an arc-shaped curved pipe is buried in the ground along the inner wall. A so-called “curve boring method” has been developed that embeds with high precision (Japan Construction Mechanization Association: Construction Mechanization Technology / Technical Review Certificate Report, Curve Boring Device (TULIP Method), 19944.8). In this curved boring method, arc-shaped pipes are sequentially connected, and finally arc-shaped pipes having a predetermined length are embedded in parallel in a plurality of strips and used as support structures.
[0003]
The present inventors, as a pipe connection method optimal for the above-described curved boring method, connect a stepped pipe with a shape memory alloy joint instead of the conventional welding connection means, and the shrinkage force of the joint As a result, a connection means for firmly fastening pipes to each other has been developed, and almost good results have been obtained in terms of workability (Japanese Patent Application No. 8-210256).
[0004]
Therefore, for example, when used as a structure such as a pipe support for a large-section tunnel, a pulling force or bending stress acts on the pipe itself. May be sufficient. Iron-based shape memory alloy is considered a kind of steel, but because it has the same austenite structure as stainless steel, it has the characteristics as a soft material that can be caused by relatively low plastic deformation compared to general steel, but plastic deformation Since the work hardening proceeds with the progress of, the fracture strength itself has a higher value than that of the ordinary high strength steel. In general piping, the pipe itself is often supported by other structures or buried in the ground, so the connection strength between the pipes depends on the contraction force due to heating of the shape memory alloy joint. In most cases, there is no problem.
[0005]
[Problems to be solved by the invention]
However, in the case of using the pipe itself as a structure, there is a tendency for the strength to be insufficient due to relying only on the shape memory effect as described above. Shape memory alloy pipe joints are easy to construct and have the great feature of being able to work safely even in tight spaces. However, on the other hand, the fastening force of the shape memory alloy joint usually depends mainly on the frictional force between the pipe outer surface and the joint inner surface. If it is plastically deformed by external force, it will be lost rapidly. In particular, when a bending stress acts on the pipe that is fastened, a strong force is generated on the end surface portion of the joint in order to expand the joint in the radial direction. Once the end portion has spread, the frictional force is reduced, and the fastening force is greatly reduced, thereby increasing the risk of disconnection of the pipe. In a pipe connection as a structure, this problem is decisive.
[0006]
In addition to the case where the pipe is used as an underground structure, a mode in which the pipe is used as a case for protecting an embedded object such as an electric wire or various cables embedded in the ground is also conceivable. In addition to a certain degree of pulling strength and bending strength, a sealing property is also required to prevent the intrusion of liquid or the like from the outside of the pipe.
[0007]
For the present invention to solve such a problem, while taking the characteristics of good workability shape memory alloy joints, also provide a pipe connection methods of high intensity that can be utilized effectively as a connection after it is structure The purpose is to do. In addition, another object of the present invention is to provide a pipe connecting means that can exhibit high sealing performance as required.
[0008]
[Means for Solving the Problems]
In order to achieve this object, the pipe connecting method according to claim 1 of the present invention is such that a curved pipe in a curved boring method in which arc-shaped curved pipes are sequentially connected and buried as a support structure after being connected. In the connection method, when the curved pipes are connected to each other by the iron-based shape memory alloy cylindrical joint, a groove is provided on the outer circumference of the fixed position from the pipe end, and on the inner circumference of the shape memory alloy cylindrical joint. Two grooves corresponding to the pipe groove are formed, and a C-shaped ring is inserted into one of the pipe side groove or the joint side groove. After inserting the pipe from both sides of the cylindrical joint, the joint is heated to a predetermined temperature. Then, it is characterized by imparting a high pulling strength to the connecting portion by contracting. The groove to be formed can have a shape in which either one or both of the pipe side or the cylindrical joint side is provided with a parallel part extending in the axial direction at the bottom, thereby aligning the pipe when the pipe is inserted into the joint. (Claim 2). The cross-sectional shape of the groove or ring may be any shape such as a circle, an ellipse, or a rectangle, but it is desirable that the groove and the ring have similar shapes. As the wire used for the ring, alloys such as high-strength steel, spring material, and stainless steel, carbon fiber, and hard resin are suitable.
Further, according to the connection method of claim 3 of the present invention, when a sealant is applied or pasted to the inner surface of the cylindrical joint in advance, and the pipe is inserted into the joint and the joint is heated and contracted, the sealant is between the pipe and the joint. The connecting portion has a high strength and a sealing property by the C-shaped ring and the sealing agent. As the sealing agent, a resin-based sealing agent having both a water stop effect and an adhesive effect is effective.
[0009]
Further, according to the connection method of claim 3 of the present invention, when a sealant is applied or pasted to the inner surface of the cylindrical joint in advance, and the pipe is inserted into the joint and the joint is heated and contracted, the sealant is between the pipe and the joint. The connecting portion has a high strength and a sealing property by the C-shaped ring and the sealing agent. As the sealing agent, a resin-based sealing agent having both a water stop effect and an adhesive effect is effective.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described based on an embodiment shown in the drawings.
FIG. 1 shows a pipe connecting means according to the present invention particularly aimed at improving the pulling strength, and is semicircular in cross section on the outer circumference of a fixed position from each end of two pipes 1A and 1B to be connected. A (U-shaped) groove 3 is provided, and two semi-circular (U-shaped) grooves 4 corresponding to the groove 3 of the pipe are formed on the inner circumference of the cylindrical joint 2 made of shape memory alloy. At the time of connection, a C-shaped ring 5 formed by bending a wire having a circular cross section as shown in FIG. 2B into a C shape is inserted into one of the groove 3 on the pipe side or the groove 4 on the joint side ( FIG. 1 shows an example in which a C-shaped ring 5 made of spring steel is inserted and held in the groove 4 on the joint side by utilizing its spring property), and pipes 1A and 1B are inserted from both sides of the cylindrical joint 2 and the C-shaped ring 5 is inserted. Is held between the corresponding grooves, and then the joint 2 is heated to a predetermined temperature and contracted, the C-shaped ring 5 is tightly held in each groove of the pipe and the joint.
[0012]
FIG. 2A shows a cross section of a connecting portion of a pipe inserted from both sides of the joint. The left side of the drawing shows a state before the joint is heated and the right side shows a state after the joint is heated. FIG. 2B is a perspective view of the C-shaped ring 5. 3A shows an AA cross section of FIG. 2, and FIG. 3B shows a BB cross section of FIG.
[0013]
In the right side of FIG. 2A and FIG. 3B, a state in which the sealing agent 6 is filled between the outer surface of the pipe 1B and the inner surface of the cylindrical joint 2 is shown. By filling the sealant 6, the pipe connection portion can be improved in its sealability and, in some cases, can be expected to increase the connection strength due to the adhesive force of the sealant. When connecting via a C-shaped ring, there is no possibility that a gap will remain between the pipe and the joint even after the joint is contracted. It can be said that it is effective.
[0014]
In order to fill this sealant, for example, a resin-based sealant (such as an epoxy resin) having both sealing performance and adhesive performance is applied in advance to the entire inner surface or a part of the inner surface of the cylindrical joint 2 before fastening (when liquid) ) Or sticking (when it is viscous and can be formed into a sheet), after inserting the pipe from both sides of the joint, the joint may be heated to shrink. When applying or sticking the sealant, even if it is not applied or attached to the entire inner surface or groove of the joint, the sealant spreads during filling and shrinkage of the joint and fills the groove without any gaps. This means for adding to the connecting portion by the resin-based sealant is effective for applications where the pipe connecting portion is required to have high sealing performance (for example, a pipe for surrounding and protecting underground objects such as cables).
[0015]
The cylindrical joint 2 is made of an iron-based shape memory alloy (for example, 28% Mn-6% Si-5% Cr-Fe alloy, 32% Mn-6% Si-Fe alloy) that is low in cost and has good workability. It is preferable that The cylindrical joint is manufactured by first manufacturing a cylinder having an inner diameter slightly thinner than the outer diameter of the pipe to be connected, and after performing memory processing (heat treatment), the cylinder has an inner diameter larger than the outer diameter of the pipe. Is obtained by expanding the diameter. Moreover, in order to remarkably improve the shape memory performance, it is possible to perform a certain processing and heat treatment at least once after the shape memory processing (training effect). In the embodiment described later, the cylindrical joint prepared first is similarly configured.
[0016]
The cross-sectional shape of the groove and the C-shaped ring is basically the above-mentioned circular shape, but a shape as shown in FIG. 4 can also be used. That is, FIG. 4A shows an example in which a C-shaped ring 15 having an elliptical cross section is used, and the pipe-side groove 13 is provided with a portion parallel to the outer surface at the bottom, and in FIG. As an example, a rectangular section is used, and parallel portions are provided at the bottoms of the grooves 23 and 24 of both the joint and the pipe. In this way, either one or both of the grooves on the pipe side or the cylindrical joint side are formed in a shape in which a parallel portion is provided at the bottom, thereby facilitating alignment when the pipe is inserted into the joint. Also in these examples, as in the example of FIG. 1, it is of course possible to fill the sealant between the pipe and the joint.
[0017]
Of course, the cross-sectional shape of the groove or the C-shaped ring is not limited to the illustrated shape, and may be any other cross-section. Further, the material of the ring may be a metal material such as high-strength steel, spring material or stainless steel, or a non-metal such as carbon fiber or hard resin.
[0018]
In the illustrated example, the case where the cylindrical joint after fastening protrudes from the outer surface of the pipe is shown, but this is for the sake of convenience of explanation, for example, when the present invention is applied to a “curved boring method” In order to connect the pipes to be laid in the borehole close to the pipe diameter, stepping is applied to at least one of the pipe and the joint as shown in Japanese Patent Application No. 8-210256. Thus, a means for preventing the outer surface of the joint after contraction from protruding from the outer surface of the pipe as much as possible can also be applied.
[0019]
【Example】
Example 1
(1) Pipe material: STK400
Dimensions: Outer diameter of 216mmφ, wall thickness of 18.5mm, length of 1000mm, both ends outer diameter of 199.1mmφ (cutting 77mm length part inserted into the joint to form a stepped part)
External groove: Machining a groove with a width of 10 mm and a corner radius of 2.0 mm on the outer periphery 45 mm from the end. (2) Shape memory alloy joint material: 28% Mn-6% Si-5% Cr-Fe alloy Dimensions: Inner diameter 202.5mmφ, wall thickness 9.7mm, length 150mm (after diameter expansion treatment)
Inner surface side groove: A U groove (groove radius 2.1 mm, depth 2.5 mm) was machined in the inner periphery at a position 30 mm from the end, and a C-shaped ring was fitted.
(3) C-shaped ring material Quality: Carbon steel oil temper for 4mmφ spring Wire dimension: Bending into a circle of 210mmφ and notching 5mm wide.
(4) When no sealant is used and when resin adhesive is applied to the inner surface and groove of the joint (5) Fastening method The joint is inserted by induction heating with pipes inserted into both sides of the joint and aligned. Was heated to 300 ° C. The inner diameter of the joint made of shape memory alloy contracted and the pipe was fastened. On the other hand, those using resin, ceramic adhesive “Sumicelam S manufactured by Asahi Chemical Industry” immediately before inserting the pipe into both the inner surface of the joint made of shape memory alloy after the diameter expansion and the U groove where the C-shaped ring is mounted. (Product name) "was applied, and fastening was performed in the same manner as when no resin was used.
[0020]
(Comparative Example 1)
(1) Pipe material: STK400
Dimensions: Outer diameter 216mmφ, wall thickness 18.5mm, length 1000mm
(2) Shape memory alloy joint material: 28% Mn-6% Si-5% Cr-Fe alloy Dimensions: inner diameter 200.1 mmφ, wall thickness 9.7 mm, length 150 mm (after diameter expansion treatment)
(3) When no sealant is used and when resin adhesive is applied to the inner surface of the joint (4) Fastening method Insert pipes on both sides of the joint, and heat the joint to 300 ° C by induction heating, shape memory alloy The inner diameter of the joint was shrunk and the pipe was fixed to complete the fastening operation. On the other hand, those using resin were fastened in the same manner as described above in a state where a ceramic adhesive “Sumicelam S (trade name) manufactured by Asahi Chemical Industry Co., Ltd.” was applied to the inner surface of the shape memory alloy joint after diameter expansion. .
[0021]
Table 1 below shows a comparison of the strength and sealability of the connecting portion obtained as a result of the pipe fastening operation performed in the above examples and comparative examples. It can be seen that the pull-out strength is remarkably improved in the example using the C-shaped ring of the present invention as compared with the case of only the contraction force of the joint made of shape memory alloy of the comparative example. In addition, as for the sealing performance, those to which a sealing agent was applied were satisfactory values. In addition, when the above-described adhesive is used as the sealing agent, the C-shaped ring is firmly fixed in the groove after the pipe is fastened, so that the object of the present invention is further enhanced.
[0022]
[Table 1]

[0023]
【The invention's effect】
As described above, according to the connection method of the present invention, when connecting a pipe using a joint for an iron-based shape memory alloy pipe, a machine such as a C-shaped ring in addition to a fastening force due to a contraction force of the joint. Therefore, a connection with higher pullout strength can be achieved. Therefore, it can be said that the pipe connecting means for leaving the pipe as a structure is particularly suitable as a connecting means applied to the curved boring method. In addition, when a resin-based sealant is used in combination, the joint strength is further enhanced and an excellent sealing property is exhibited, so that it is particularly effective when applied to a connection portion that requires a sealing property.
[Brief description of the drawings]
FIG. 1 is a partial cross-sectional view showing an embodiment of connecting means according to the present invention.
2A is a cross-sectional view of a pipe connecting portion fastened by the means in FIG. 1, and FIG. 2B is a perspective view of a C-shaped ring.
3A is a cross-sectional view taken along line AA in FIG. 2, and FIG. 3B is a cross-sectional view taken along line BB in FIG.
4 is a cross-sectional view showing another example of the embodiment of FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Pipe 2 Shape memory alloy pipe cylindrical joint 3, 13.23 Pipe side groove 4, 24 Joint side groove 5, 15, 25 C type ring 6 Sealant

Claims (3)

In the method of connecting curved pipes in a curved boring method in which arc-shaped curved pipes are sequentially connected and connected as a support structure after being connected, the curved pipes are connected to each other by an iron-based shape memory alloy cylindrical joint. At this time, either one of the groove provided on the outer circumference of the pipe at a fixed position from the end of the pipe and the two grooves corresponding to the groove of the pipe provided on the inner circumference of the cylindrical joint is previously C. The pipe is characterized in that a high ring strength is given to the connecting portion by inserting a ring and inserting the pipe from both sides of the cylindrical joint and then heating and shrinking the joint to a predetermined temperature. Strength connection method.   The high strength connecting method of a pipe according to claim 1, wherein a parallel portion extending in the axial direction is formed on a bottom surface of at least one of the groove of the pipe and the groove of the cylindrical joint.   The high strength connection method for pipes according to claim 1 or 2, wherein a sealant is applied or pasted in advance to the inner surface of the cylindrical joint before the pipe is inserted.

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