JP2006336340A - Joint protection structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a joint protection structure for positively protecting the outer peripheral surface of a pipe joint to prevent flawing when pulling a jacking pipe into a through hole in a non-open-cut jacking method. <P>SOLUTION: In the non-open-cut jacking method, an excavating pipe is allowed to enter from a penetration pit in a piping work section to form a through hole up to an arrival pit, then a jacking pipe 3 is connected to the tip of the excavating pipe in the arrival pit, and the excavating pipe is towed along the through hole to lay the jacking pipe 3 from the arrival pit to the penetration pit. The jacking pipes 3 are joined to each other through a pipe joint 4, and a joint protective cover 2 is disposed at the jacking pipe 3, in a position near a penetration pit side joint part to the pipe joint 4 to prevent flawing on the outer peripheral surface of the pipe joint 4. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a joint protecting structure for a propulsion pipe used in a non-open-cut propulsion method.

  In recent years, as a method of piping underground such as water supply piping, sewer piping, gas piping, etc., a non-cutting propulsion method that can lay a pipe without greatly cutting the ground has been used. A non-cutting propulsion method called “construction method” is disclosed in Patent Document 1. This non-open-cut propulsion method has the advantage that the construction period can be shortened compared to the conventional open-cut method, and the cost can be reduced by greatly reducing the cut-off area, and the traffic regulations on the road can be relaxed. Have.

  The non-cutting propulsion method is generally performed as follows.

  First, the ground at both ends of the piping work section is excavated in the vertical direction to provide an intrusion mine and a reaching mine. A drill head attached to the tip of the excavation pipe is entered from the penetrating pit, and a through hole is formed by excavating the reaching pit with the guidance of a tip position detector on the ground. Next, the drill head at the tip of the drilling pipe is removed at the reaching pit, and a propulsion pipe is connected to the tip of the drilling pipe instead. Thereafter, by pulling the excavation pipe in the reverse direction along the through hole, the propulsion pipe is drawn to the penetration pit, and the laying of the propulsion pipe by non-opening is completed.

By the way, in such a non-open-cut propulsion method, since the length of the propulsion pipe is short with respect to the piping work section, the plural propulsion pipes are used while being joined by a pipe joint.
Japanese Patent Publication No. 58-38598

  As the pipe joint, a cylindrical one having a receiving port at both ends is generally used. When the propulsion pipe is joined through the pipe joint in this way, the pipe joint protrudes to the outer peripheral side of the propulsion pipe. Therefore, when the propulsion pipe is pulled, stones, gravel, etc. with sharp through-hole inner walls are Contact with the outer peripheral surface of the joint will damage the pipe joint or cause sharp scratches on the outer peripheral surface.

  By the way, when an electrofusion pipe joint is used as a pipe joint, a step part having a smaller diameter than the inner diameter of the receiving port is formed at the inner peripheral side intermediate part of the pipe joint, The tube end surface of the tube and the vicinity of the outer peripheral surface of the tube end may not be fused. In this state, when a fluid is supplied to the laid propulsion pipe, the fluid enters the non-fused portion described above and tries to expand the pipe joint by the pressure of the fluid. Here, as described above, if the outer peripheral surface of the pipe joint has a sharp flaw, stress concentrates on the flaw due to the notch effect. For this reason, there was a problem that the scratches progressed inward and finally penetrated, causing accidents such as water leakage and gas leakage.

  In order to solve this problem, as shown in FIG. 4, the protective tape 50 and the heat-shrinkable tube are wound over a certain range of the pipe joint and the front and rear propulsion pipes 30 joined to the pipe joint. Attempts have been made to prevent damage.

  However, since the protective tape 50 and the heat-shrinkable tube are thin and weak in strength, the protective tape 50 and the heat-shrinkable tape may be peeled off from the pipe joint when they come into contact with a sharp stone or gravel on the inner wall of the through hole. Many. For this reason, a pipe joint will be in a bare state and will be damaged. As a result, the protective tape 50 and the heat shrinkable tube have a problem that the pipe joint cannot be sufficiently protected.

  The present invention has been made in view of such circumstances, and its purpose is to reliably protect the outer peripheral surface of the pipe joint and prevent scratches when the propulsion pipe is pulled into the through hole by the non-cutting propulsion method. It is in providing the joint protection structure which can do.

  In order to solve the above-described problem, the joint protection structure of the present invention is configured such that a drill pipe is entered from an intrusion pit in a piping work section, a through hole is formed up to the arrival mine, and then a propulsion pipe is formed at the tip of the digging pipe in the arrival mine In the non-open-cut propulsion method that pulls the excavation pipe along the through hole and lays the propulsion pipe from the reaching pit to the penetration pit, the propulsion pipes are joined to each other via a pipe joint. The propulsion pipe is positioned in the vicinity of the penetration pit side joint with the pipe joint, and a joint protection cover is provided to prevent the outer peripheral surface of the pipe joint from being damaged.

  According to such a joint protection structure, when the propulsion pipe is drawn into the through hole, the sharp stone or gravel on the inner wall of the through hole collides with the joint protective cover. Can get over without touching the pipe joint. Accordingly, the pipe joint can be protected, and damage to the pipe joint and damage to the outer peripheral surface can be prevented.

  Further, the joint protective cover may be a tapered surface whose outer peripheral surface is expanded in diameter from the front end on the penetration shaft side to the rear end on the arrival shaft side.

  In this case, since the outer peripheral surface of the joint protective cover is tapered, the propelling pipe can be pulled in while spreading stones and gravel on the inner wall of the through hole with the joint protective cover, and the pipe joint is damaged or damaged. Can be prevented, and the resistance when the propulsion pipe is retracted can be reduced.

  The joint protection cover has a shape corresponding to an end surface on the penetration shaft side of the pipe joint, and an outer diameter of the rear end on the arrival shaft side is an outer diameter of the pipe joint. It may be larger than that.

  In this case, when pulling the propelling pipe into the through hole, the joint protective cover can prevent sharp stones or gravel on the inner wall of the through hole from coming into contact with the pipe joint. Damage can be prevented.

  In addition, the end face of the joint protection cover at the end of the mine shaft has a shape that corresponds to the end face of the pipe joint. And the penetration pit side end face of the pipe joint can be brought into contact with each other. Therefore, a gap is not formed between the end face on the rear end of the pit side of the joint protection cover and the end face on the penetration pit side of the pipe joint, and stones, gravel, etc. that have collapsed from the inner wall of the through hole enter the gap. The pipe joint is not damaged.

  In the present invention, the material of the propelling tube is not particularly limited, and for example, polyethylene, polybden, etc. excellent in flexibility can be used. The propulsion tube may be a single layer, but in the case of a synthetic resin tube that is easily damaged, it is preferable to use a multilayered synthetic resin tube whose outer peripheral surface is protected by a protective layer. .

  In the present invention, the material for the pipe joint is not particularly limited, and for example, polyethylene, polybden, etc. excellent in flexibility can be used. The pipe joint may be of a single layer, but in the case of a synthetic resin pipe that is easily damaged, it is preferable to use a synthetic resin pipe whose outer peripheral surface is formed into a multilayer by a protective layer. Moreover, the electrofusion pipe joint generally used for a polyethylene pipe can be used for a pipe joint.

  In the present invention, the material for the joint protective cover is not particularly limited, and for example, a synthetic resin such as polyethylene, polyacetal, or polyvinyl chloride excellent in impact resistance and flexibility, metal, or the like can be used.

  The joint protective cover may be configured such that the outer diameter of the rear end on the arrival shaft side is larger by about 10 to 20 mm than the outer diameter of the pipe joint. When the outer diameter difference is less than 10 mm, the pipe joint cannot be sufficiently protected from the sharp stone or gravel on the inner wall of the through hole when the propulsion pipe is pulled. The resistance when pulling in will increase.

  In addition, a protective tape is wound in advance over a certain range of the pipe joint and the front and rear propulsion pipes joined to the pipe joint, and from there, the joint is placed in the vicinity of the joint on the penetration pit side between the propulsion pipe and the pipe joint. By providing the protective cover, the pipe joint can be further prevented from being damaged.

  In this case, the joint protective cover may be provided with a slit over the entire length in the longitudinal direction. As a result, when a force is applied to the joint protective cover from the front when the propulsion pipe is pulled in, the slit is closed and the diameter of the joint protective cover is reduced, so that the propulsion pipe wound with the protective tape and the joint protective cover are in close contact with each other. Thus, the joint protective cover can be made difficult to shift from the position of the joint portion between the propulsion pipe and the pipe joint on the penetration mine side. Moreover, this joint protective cover can be easily attached from the side of the propulsion pipe by opening a slit.

  The joint protective cover of the present invention has an effect that when the propulsion pipe is drawn into the through hole by the non-cutting propulsion method, the outer peripheral surface of the pipe joint can be reliably protected to prevent damage.

  Hereinafter, embodiments of the present invention will be described with reference to FIG. 1 and FIG.

  1 and 2 show an embodiment of a joint protection structure 1 according to the present invention (hereinafter referred to as Example 1). In the figure, the joint protection structure 1 of the present embodiment includes a propulsion pipe 3, a pipe joint 4, and a joint protection cover 2 used in the non-cutting propulsion method.

  The propulsion pipe 3 was a polyethylene pipe for water distribution with an outer diameter of 90 mm, in which the surface of the polyethylene pipe was coated with polyamide resin and polyethylene in order.

  The pipe joint 4 is an electrofusion pipe joint, and the material thereof is the same as that of the propulsion pipe 3, and the surface of the polyethylene pipe is coated with polyamide resin and polyethylene in this order. In this electrofusion fitting, a wire is wound inside, and a contact surface between the propulsion tube 3 and the electrofusion fitting can be melted and joined by passing an electric current through the wire. The pipe joint 4 used had an outer diameter of 120 mm and a length of 130 mm, and both ends of the outer peripheral surface were chamfered.

  The joint protective cover 2 is made of polyacetal, and is set so as to cover the penetration pipe side end face 41 of the pipe joint 4 to the propulsion pipe 3 50 mm ahead. Here, the joint protective cover 2 has an inner peripheral surface of 90 mm in inner diameter and a uniform circular cross section, and the outer peripheral surface extends from the penetration mine side front end 21 having an outer diameter of 90 mm to the reaching mine side rear end 22 having an outer diameter of 130 mm. Further, the end face of the reaching mine side rear end 22 is formed so as to match the chamfered end face shape of the pipe joint 4. And when the end face of the reaching mine side rear end 22 of the joint protection cover 2 is abutted against the penetration mine side end face 41 of the pipe joint 4, the rear end edge of the outer peripheral surface is more than the penetration mine side end face 41 of the pipe joint 4. It is set to be located at the rear.

  FIG. 3 shows a modification of the joint protection structure 1 according to the present invention (hereinafter referred to as Example 2). The joint protection structure 1 according to this modification includes a propulsion pipe 3 used for the non-cutting propulsion method, a pipe joint 4, a joint protective cover 2, and a protective tape 5.

  Since the joint protection structure 1 of this modification has the same configuration as the joint protection structure 1 of the first embodiment described above except for the protective tape 5 and the joint protection cover 2, the same reference numerals are assigned to the same members. Therefore, the description is omitted, and only the protective tape 5 and the joint protective cover 2 which are different points will be described.

  The protective tape 5 was made of soft vinyl chloride and had a thickness of 0.5 mm. The protective tape 5 was spirally wound over the propulsion pipe 3 on the penetrating mine side through the pipe joint 4 and over the propulsion pipe 3 on the arrival pit side while being overlapped by ½ width. In this case, if the winding start position of the protective tape 5 around the propulsion pipe 3 is set so as to be concealed by the joint protective cover 2 described later, when the propulsion pipe 3 is pulled, the protective tape 5 is turned up and peeled off from the winding start portion. Can be eliminated.

  The joint protective cover 2 is made of polyacetal and is set so as to cover from the end face of the pipe joint 4 to the propulsion pipe 3 50 mm ahead, as shown in the figure. Further, the inner diameter of the joint protective cover 2 is slightly larger than 92 mm and the outer diameter 90 mm of the propulsion pipe 3, and a clearance is provided between the propulsion pipe 3. The protective cover 2 can be disposed.

  Here, the joint protective cover 2 has an inner peripheral surface of 92 mm in inner diameter and a uniform circular cross section, and the outer peripheral surface extends from the penetration mine side front end 21 having an outer diameter of 92 mm to the reaching mine side rear end 22 having an outer diameter of 130 mm. Further, the end face of the reaching mine side rear end 22 is formed so as to match the chamfered end face shape of the pipe joint 4. And when the end face of the reaching mine side rear end 22 of the joint protection cover 2 is abutted against the penetration mine side end face 41 of the pipe joint 4, the rear end edge of the outer peripheral surface is more than the penetration mine side end face 41 of the pipe joint 4. It is set to be located at the rear.

  The joint protective cover 2 is provided with slits 23 opened at intervals of 2 mm over the entire length in the longitudinal direction. Thereby, when pulling in the propulsion pipe 3, if a force is applied to the joint protective cover 2 from the front, the slit 23 is closed and the diameter of the joint protective cover 2 is reduced. Adhesiveness with the joint protection cover 2 is increased, and the joint protection cover 2 can be made difficult to shift from the position of the penetration mine side joint between the propulsion pipe 3 and the pipe joint 4. The joint protective cover 2 can be easily attached from the side of the propulsion pipe 3 by opening the slit 23.

  Next, the test results when the pull-in test is performed by the non-cutting propulsion method for the joint protection structure 1 of the above-described example 1, the above-described example 2, and the conventional example will be shown.

  Here, as shown in FIG. 4, the propulsion pipe 30 is joined to the joint protection structure 10 of the conventional example by a pipe joint, and the protective tape 50 passes through the pipe joint 4 from the propulsion pipe 3 on the penetrating pit side. It is wound around the propulsion pipe 3 on the arrival mine side in a spiral shape while being overlapped by ½ width.

  The pull-in test was performed as follows using a flow molding method between an intrusion shaft and a reaching shaft at a distance of 100 m.

  First, the drill head attached to the tip of the excavation pipe is entered from the penetration pit, and bentonite mud is jetted from the drill head to cut and excavate the soil. Next, the excavation pipe is guided to the reaching pit while being confirmed by the flow categorizer. When the tip of the excavation pipe reaches the reaching pit, the drill head attached to the tip is replaced with an enlarged diameter reamer, and the propulsion pipe 3 is connected to the enlarged diameter reamer. Again, while the bentonite mud is jetted from the expanded reamer, the diameter of the through hole is increased by drawing the propulsion pipe 3 into the through hole, and the propulsion pipe 3 is smoothly laid. After the propulsion pipe 3 reached the position of the penetration pit, the joint portion between the propulsion pipe 3 and the pipe joint 4 and the front and rear portions thereof were taken out from the ground, and the respective states were observed.

  In the joint protection structure 10 of the conventional example, the protective tape 50 is peeled off on the entire surface of the pipe joint, and a sharp scratch having a depth of about 1 mm is generated in the pipe joint. Further, in the joint protection structure 1 of Example 1, the joint protection cover 2 was torn, but the pipe joint 4 was not damaged. In the joint protection structure 1 of Example 2, the joint protective cover 2 was torn, but the pipe joint 4 was not damaged.

  As described above, in the joint protection structure 10 of the conventional example, a sharp flaw is generated in the pipe joint. However, in the joint protection structure 1 in the first and second embodiments, the pipe joint 4 is damaged or scratched. It never happened.

It is a perspective view which shows the joint protection structure in this invention. It is sectional drawing which shows the joint protection structure in this invention. It is a perspective view which shows the joint protection structure of the modification in this invention. It is a perspective view which shows the conventional joint protection structure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Joint protection structure 2 Joint protection cover 21 Front end 22 of a penetration hole of a joint protection cover Rear end 23 of a penetration side of a joint protection cover Slit 3 Propulsion pipe 4 Pipe joint 41 End face 42 side of a pipe joint Penetration side of a pipe joint End face 5 Protective tape

Claims (3)

After the excavation pipe is entered from the penetration pit of the piping work section and a through hole is formed up to the reaching pit, a propulsion pipe is connected to the tip of the excavation pipe in the reaching pit, and the excavation pipe is pulled along the through hole In the non-cutting propulsion method of laying the propulsion pipe from the reaching pit to the penetration mine,
While joining the propulsion pipes together via a pipe joint,
A joint protection structure characterized in that a joint protection cover is disposed in the vicinity of a penetration joint side joint portion with a pipe joint of the propulsion pipe to prevent damage to the outer peripheral surface of the pipe joint.   2. The joint protection structure according to claim 1, wherein the joint protection cover is a tapered surface whose outer peripheral surface is enlarged in diameter from the front end on the penetration mine side to the rear end on the arrival mine side.   The joint protection cover has a shape corresponding to the end surface on the penetrating pit side of the pipe joint, and the outer diameter of the rear end on the pit side is larger than the outer diameter of the pipe joint. The joint protection structure according to claim 2, wherein the joint protection structure is provided.

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