JP3849032B2 - Protecting buried pipes - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for protecting a buried pipe laid in the ground from being damaged by other construction such as road construction and building construction in the vicinity performed after laying.
[0002]
[Prior art]
In general, important buried pipes such as high-pressure gas trunk lines buried in the ground ensure strength against internal and external pressures, and are also used for nearby road construction, construction work, and other buried construction work. It is necessary to protect it from being damaged by construction machines such as backhoes.
[0003]
Conventionally, as this protective means, as shown in FIG. 9, a protective plate 5 made of a steel plate or reinforced concrete having a width larger than the outer diameter of the buried pipe 2 is provided horizontally at a position about 30 cm above the buried pipe 2. A double pipe method is used in which protective pipes such as steel pipes, fume pipes, corrugated pipes and the like are provided outside the pipes and buried pipes. In the case of the latter double pipe system, a filling material such as sand or air mortar is filled in the gap between the buried pipe and the protective pipe.
[0004]
[Problems to be solved by the invention]
In the case of the protection plate method of the prior art, since the protection plate 5 is installed only above the buried pipe, the side surface cannot be protected in the drilling work such as horizontal and oblique boring. There is a problem that it may cause damage. On the other hand, in the case of the double pipe method using a protective pipe, it can protect the entire circumference of the buried pipe, but the laying work of the buried pipe and the protective pipe and the filling material filling the gap between the buried pipe and the protective pipe There is a problem that the filling operation is difficult and the cost is increased.
[0005]
The present invention solves the problems of the prior art, and installs protective plates on the upper surface and both side surfaces that may damage the buried tube by a simple work method, and securely buryes the buried tube at a low cost. The purpose of this is to provide a method for protection of coatings, and to enable coating damage inspection to be performed from the ground surface after laying buried pipes.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the configuration of the present invention is as follows.
In the buried pipe protection method according to claim 1, the portal frame 3 made of synthetic resin is arranged at intervals in the pipe axis direction so as to cover the buried pipe 2 laid in the excavation groove 1. After the side protection plates 4 are fixed vertically on both sides of the portal frame 3, the lower backfill earth and sand 6 is filled in the excavation groove 1 and backfilled to the upper end of the portal frame 3, and then the upper surface protection is performed. The plate 5 is disposed horizontally, and the upper layer backfill earth and sand 7 is charged and compacted to protect the side surface and the upper surface of the buried pipe 2.
[0007]
According to a second aspect of the present invention, in the buried pipe protection method according to the first aspect, the portal frame 3 is provided with a base 3d having a groove 3f into which the lower end of the side protection plate 4 is inserted at the lower end. The corner portion is provided with a detachable U-shaped fixture 9 for fixing the upper end portion of the side protection plate 4 so that the side protection plate 4 can be easily attached.
[0008]
According to a third aspect of the present invention, in the method for protecting a buried pipe according to the first or second aspect, a steel plate having a length L that can be electrically conductive is used as the side surface protective plate 4 and the upper surface protective plate 5, and the respective protective plates are used. A plurality of pipe axial end portions are placed in an electrically insulated state so as to form an overlapped portion 10, and are obtained by a buried pipe coating damage inspection apparatus 12 electrically performed from the ground surface. It is possible to specify the damage position 14 from the inspection result obtained.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
(Embodiments and Examples of the Invention)
DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments and examples of a buried pipe protection method according to the present invention will be described with reference to the drawings.
FIG. 1 is a front view of an installed state of protective plates 4 and 5 arranged outside the buried pipe 2 by carrying out the buried pipe protecting method of the present invention, FIG. 2 is a side view thereof, and FIG. The figure is shown. 4 to 6 are a front view, a plan view, and a fixture 9 for the side protection plate 4 of the portal frame 3 used in the present invention.
[0010]
In the buried pipe protection method according to the present invention, the side face protection plate 4 and the top face protection plate 5 are arranged vertically and horizontally, respectively, with a gap between both side surfaces and the upper surface of the buried pipe 2 in the excavation groove 1, and backfilling earth and sand. 6 and 7 are used to prevent damage to the buried pipe 2 due to nearby road construction, buried construction work, or the like.
[0011]
The side protection plate 4 and the top protection plate 5 to be used are steel plates that have strength against impact loads from the outside such as a boring device and excavation device and are easy to handle. When steel plates are used for the protective plates 4 and 5, there is also an advantage that an operator can easily detect on the start side when a boring device such as a boring is in contact. In addition, as a steel plate for the protective plate, if ordinary steel is used, the plate thickness should be about 9 mm, but if high-tensile steel is used, a thinner plate thickness (about 6 mm) can be used and is lightweight. Can be
[0012]
The height and width of the side protection plate 4 and the top protection plate 5 are determined depending on the size (diameter) of the excavation groove 1 and the buried pipe 2. For example, a 600 mm diameter is provided in the excavation groove 1 having a depth of 1.8 m and a width of 1.2 m. In the case of applying to the pipe with the buried pipe 2 installed, the height of the side protection plate 4 may be about 1 m, and the width of the top protection plate 5 may be about 1 m. The length of each protection plate 4 and 5 in the tube axis direction is about 2 to 3 m, and the protection plate 4 (5) adjacent in the tube axis direction is wrapped (polymerized) by about 10 cm to form the overlapping portion 10. Install as provided.
[0013]
The portal frame 3 is provided to install the side protection plate 4 outside the buried pipe 2 perpendicularly to the predetermined arrangement, and is arranged so as to cover the buried pipe 2 at intervals of about 1.5 m in the pipe axis direction. ing. The portal frame 3 is made of a synthetic resin such as polyethylene or vinyl chloride so that the coating of the buried pipe 2 is not damaged even if it moves in the ground in the event of an earthquake. Moreover, you may use what recycled plastic waste material.
[0014]
A portal frame 3 shown in FIG. 4 (front view) and FIG. 5 (plan view) is formed by assembling a pair of column members 3a and beam members 3b made of these materials into a portal shape with bolts and nuts 3c. A pedestal 3d in which a groove 3f into which the lower end of the side protection plate 4 is inserted is formed at the lower end of 3a, and is fixed with bolts 3e and nuts inserted through the through holes of the pillar 3a and the pedestal 3d. is doing. The upper surface of the upper portion of the pedestal 3d supports the lower end of the side protection plate 4, and the lower end of the side protection plate 4 is supported at a predetermined position by a concave groove 3f formed in cooperation with the column member 3a. Is done.
[0015]
A beam receiving recess 3h is formed between a pair of support arms 3g provided so as to be opposed to the upper end of each column member 3a integrally with each other, and an end of the beam member 3b is formed in the recess 3h. A plurality of bolts (and nuts screwed into the bolts) inserted through the support arms 3g and the plurality of through holes in the insertion projections 3j of the beam member 3b. It is fixed integrally with 3c, and it opened upward between each vertical surface 3k and pillar material 3a at right angles to the insertion convex part 3j on both sides of the base part of the insertion convex part 3j of the beam member 3b. A gap is provided, and a slit 9c described later is formed by the gap. In addition, a detachable U-shaped fixture 9 for fixing the upper end portion of the side protection plate 4 is fitted and placed at the upper end corner portion of the column member 3a, and a holding plate 9e described later is provided on the outer surface of the column member 3a. Are provided so as to face each other at an interval.
[0016]
The U-shaped fixture 9 is made of, for example, steel and is integrally bent at one end of a substantially rectangular top plate 9d as shown in FIGS. 6 (a), 6 (b), and 6 (c). A pair of projecting pieces 9b inserted into and locked to each slit 9c provided at the upper end of the portal frame 3, and provided so as to face the projecting pieces 9b with a space therebetween, and an upper surface plate A holding plate 9e integrally bent at the other end of 9d, and a fixing bolt 9a that is screwed into a female screw hole provided in the holding plate 9d and that fastens and fixes the side protection plate 4 toward the portal frame 3 I have. When the gate-type frame 3 configured in this way is used, the side protection plate 4 is set by inserting the lower end of the side protection plate 4 into the groove 3f of the pedestal 3d of the column member 3a, and then connecting the protruding piece 9b of the U-shaped fixture 9 The upper part of the side protection plate 4 can be fastened and fixed with the fixing bolt 9a by being inserted into and locked in the slit 9c of the mold frame 3, so that the side protection plate 4 can be installed very easily.
[0017]
A case where the coating damage inspection of the buried pipe is performed from the ground surface after the protective plate is installed will be described. The coating damage inspection of buried pipes is, for example, “Iron Steel Research No. 334” (1989), pages 55-61, published by Nippon Steel Corporation. Refer to “Development”. In this inspection method, as shown in FIG. 7B, the signal current 13 is applied between the buried pipe 2 and the Mg electrode 13a buried in the ground, along the ground surface immediately above the buried pipe 2. The coating damage inspection apparatus 12 including the wheel electrodes 12a is run, and the potential difference 12b due to the leakage current from the coating damage portion 14 is measured.
[0018]
In order to enable the coating damage inspection of the buried pipe from the ground surface after the protection plate is installed, the protection plate made of steel plate is entirely or partially unpainted to make each protection plate 4 (5) conductive. It is necessary to provide primary rust prevention (rust-prevention coating) and insulate the pipe axis direction at predetermined intervals L. The insulation distance L in the tube axis direction is an insulating material such as a belt-shaped rubber plate as shown in FIG. 8 in a portion (overlapping portion 10) where the protective plate 4 (5) having a length of about 2 to 3 m is arranged approximately 10 cm. It may be set by interposing 11.
[0019]
With this configuration, the damage position is specified for each insulation interval (protection plate length) L from the inspection result (distribution data of ground surface potential difference V) as shown in FIG. 7A obtained by the coating damage inspection. can do. (However, the damage position within the insulation interval L cannot be specified)
[0020]
The maximum value of the potential difference V is inversely proportional to the protective plate length L. The longer the protective plate is, the smaller the maximum value of the potential difference V becomes and it becomes difficult to identify damage. (2 to 3 m as described above). However, if the length L of the protective plate is made too short in order to increase the accuracy of damage inspection, workability will be reduced. Considering both, it is desirable that the protective plate length L is about 2 to 3 m.
[0021]
Hereinafter, a procedure for installing the protective plate around the buried pipe using the protective plate, the portal frame or the like will be described.
{Circle around (1)} First, the portal frame 3 is arranged at appropriate intervals across the buried pipe 2 laid in the excavation groove 1. At this time, if the sandbag 8 is sandwiched between the buried pipe 2 and the portal frame 3, even if the portal frame 3 sinks, the coating of the buried pipe 2 is not damaged. The distance between the upper end of the buried pipe 2 and the lower surface of the upper end of the portal frame 3 is about 30 cm.
(2) Next, the side protection plate 4 is set on the portal frame 3 by the above-described means, and extended while forming the overlapping portion 10 so as to overlap the end portions of the side protection plates 4 adjacent in the tube axis direction. . The overlap portion 10 is provided with an insulating material 11 such as a rubber plate interposed.
{Circle around (3)} When all the side protection plates 4 have been set, the lower layer backfill earth and sand 6 is put into the excavation groove 1 and backfilled slightly above the upper end of the portal frame 3 while being compacted. At this time, the sand that has not been rolled around the buried pipe 2 is compacted by water-tightening.
(4) Next, on the lower backfill earth and sand 6, like the side protection plate 4, the upper protection plate 5 is set horizontally so that an insulating material 11 such as a rubber plate is interposed in the overlapping portion 10. Then, the upper layer backfill earth and sand 7 is introduced and backfilled to a predetermined height while rolling and compacting with a rammer or the like. It is desirable that the upper surface protection plate 5 is positioned slightly above the upper end of the portal frame 3.
(5) Complete asphalt pavement if necessary.
[0022]
When practicing the present invention, the entire portal frame may be integrally formed.
[0023]
【The invention's effect】
A portal frame made of synthetic resin is arranged at intervals in the tube axis direction so as to cover the buried pipe piped in the excavation groove, and side protection plates are placed vertically on both sides of the portal frame. After fixing, fill the bottom of the excavation ditch with the lower layer backfilling sand and backfill to the upper end of the gate-type frame, then arrange the upper protection plate horizontally, fill the upper layer backfilling sand and tighten the Since the side and top surfaces are protected, protective plates can be installed on the top surface and both side surfaces that may damage the buried pipe with a simple work method, and the buried pipe can be reliably protected at low cost. .
[0024]
The portal frame includes a pedestal having a groove for inserting the lower end of the side protection plate at the lower end, and a detachable U-shaped fixture for fixing the upper end of the side protection plate at the corner of the upper end. It is possible to facilitate installation of the side protection plate.
[0025]
The side protection plate and the top protection plate use steel plates of length L that can conduct electricity, and by arranging a large number of each protection plate in an electrically insulated state by overlapping them in the axial direction, Therefore, it is possible to carry out the coating damage inspection of the buried pipe which is electrically performed from the beginning, and the damage position can be identified from the obtained inspection result.
[Brief description of the drawings]
FIG. 1 is a front view showing an installation state of a protection plate for a buried pipe in accordance with the present invention.
FIG. 2 is a side view of FIG.
3 is a plan view of FIG. 1. FIG.
FIG. 4 is a front view of a portal frame used in the present invention.
5A is a plan view of FIG. 4, and FIG. 5B is a plan view showing a state in which a U-shaped fixture is removed.
6A is a front view of a U-shaped fixture, FIG. 6B is a plan view thereof, and FIG. 6C is a side view thereof.
FIG. 7A is a distribution diagram of a ground surface potential difference obtained by coating damage inspection, and FIG. 7B shows a configuration of a buried pipe coating damage inspection apparatus and a situation where damage inspection is performed. It is a schematic side view shown.
FIG. 8 is a diagram showing an overlapping portion of each protection plate.
FIG. 9 is a longitudinal sectional front view showing a conventional protection method.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Excavation groove 2 Buried pipe 3 Portal frame 3a Column material 3b Beam material 3c Bolt / nut 3d Base 3e Bolt 3f Groove 3g Support arm 3h Recess 3j Insertion convex part 3k Vertical surface 4 Side surface protection plate 5 Upper surface protection plate 6 Lower layer filling Back soil 7 Upper layer back soil 8 Sandbag 9 U-shaped fixture 9a Fixing bolt 9b Projection piece 9c Slit 9d Top plate 9e Holding plate 10 Overlap 11 Insulating material 12 Coating damage inspection device 13 Signal current 14 Coating damage Part

Claims (3)

A portal frame made of synthetic resin is arranged at intervals in the tube axis direction so as to cover the buried pipe laid in the excavation groove, and side protection plates are vertically arranged on both sides of the portal frame. After fixing, fill the bottom of the excavation groove with the lower backfilling sand and backfill up to the upper end of the portal frame, then place the upper protection plate horizontally, fill the upper backfilling sand and tighten the A method of protecting a buried pipe, characterized by protecting a side surface and a top surface. The portal frame is provided with a pedestal having a groove for inserting the lower end of the side protection plate at the lower end, and a detachable U-shaped fixture for fixing the upper end of the side protection plate at the corner of the upper end. 2. The buried pipe protecting method according to claim 1, wherein the side guard plate is easily attached. A conductive steel plate of length L is used as the side protection plate and the top protection plate, and a large number of each protection plate are arranged in an electrically insulated state in an electrically insulated state. The method for protecting a buried pipe according to claim 1 or 2, wherein a damage position can be specified from an inspection result obtained by a coating damage inspection apparatus for buried pipe.

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