JP4036305B2 - How to line underground pipes - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for lining a pipeline buried in the ground for the purpose of repair or reinforcement.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, lining is carried out for the purpose of repairing or reinforcing a damaged portion of a pipeline buried in the ground. In order to apply a lining to the pipe line, both ends of the pipe part to be lined are dug up, the pipe line is cut, and the lining material is inserted into the pipe part from the end, and the inner pressure is applied to the lining material. It is in pressure contact with the road surface.
[0003]
Various methods have been proposed for the structure of the lining material and the means for inserting the lining material into the pipe line portion, but in many cases, a step of heating the lining material is required in the lining work.
[0004]
For example, an airtight layer is formed on the inner surface of a fiber layer such as a tubular woven fabric to form a lining material, and the fiber layer of the lining material is impregnated with a reaction-curable resin liquid and inserted into a pipe portion, and the lining material There is a method in which a heated and pressurized fluid is fed into the inner surface so that the lining material is pressed against the inner surface of the pipe and the resin liquid is heated and cured to be lining.
[0005]
Also, a thermoplastic resin or a pipe reinforced with a cylindrical fiber layer is used as a lining material, and this is inserted into a pipe line to feed a heated pressurized fluid, and the thermoplastic resin is removed by the heat of the heated pressurized fluid. There is also known a method of softening and inflating with an internal pressure, and lining by pressing against the inner surface of the pipeline.
[0006]
[Problems to be solved by the invention]
However, in these methods, the pipe line may suddenly break immediately after the lining or after a certain time has passed. In particular, in a pipe line system in which steel pipes are welded by non-back welding, in the case of a long pipe line exceeding 30 m, the length that can be lined by a single operation is often not broken at the welding point. The work efficiency was poor.
[0007]
The results of the study of this phenomenon are described in detail in the 39th Annual Conference of the Japan Society of Civil Engineers (1984) “Stresses in buried pipes due to thermal expansion and contraction history: Shoichi Iimura, Nobuaki Nishio” Yes.
[0008]
The contents of this academic paper can be briefly explained as follows. That is, as shown in FIG. 3, thermometers and strain gauges are attached to 13 approximately equidistant intervals of (1) to (13) on a pipe 1 of about 80 m of steel pipe embedded in 1 m underground, and a to Displacement gauges were installed at approximately seven regular intervals. Then, steam is fed from one end of the pipe and heated until the tube temperature rises by about 60 ° C (about 69 minutes), after which the steam is stopped and cooled naturally over 12 days. The temperature, strain and displacement at each measurement point are measured.
[0009]
FIG. 4 is a graph showing the relationship between the temperature at each point a to g and the amount of displacement in the test results. FIG. 4 shows the temperature and strain at the points (2), (4), (6) and (7). FIG. 5 shows a graph showing the relationship between the In the academic paper, more data is shown, but it is omitted here.
[0010]
Thus, according to FIG. 4, at the center point d of the pipe line 1, almost no displacement occurs regardless of the temperature change. Further, at the points a, b, and c in the left half, a displacement to the left occurs due to the execution of the test, and at the points e, f, and g in the right half, a displacement to the right occurs. As the distance increases, the amount of displacement increases in proportion to the distance, and it can be understood that the pipe line 1 extends from the center as the test is performed.
[0011]
Looking at the amount of displacement at each measurement point, displacement occurs when the temperature begins to rise, and the amount of displacement increases as the temperature rises. When the temperature of the pipe line 1 is cooled after the temperature is raised to about 80 ° C., the amount of displacement is reduced and the pipe line 1 is contracted, but the contraction speed is delayed from the extension speed due to the temperature increase.
[0012]
Even when the pipe line 1 is sufficiently cooled and returned to room temperature, the amount of displacement does not return to zero, and the pipe line 1 remains slightly expanded.
[0013]
Further, according to FIG. 5, compressive strain is generated in the pipe line 1 as the heating starts, and the amount of strain increases as the temperature rises. The magnitude of distortion at each measurement point is the largest at the center (7) and the smallest at the (2) point close to the terminal.
[0014]
When the temperature of the pipe line 1 is cooled after the temperature is raised to about 80 ° C., the compressive strain rapidly decreases, and tensile strain is generated beyond zero. As the temperature decreases, the tensile strain increases and settles to a constant value. Even when the temperature returns to room temperature, the tensile strain remains, and the magnitude thereof is approximately the same as the maximum value of the compressive strain generated during heating.
[0015]
From these results, the following can be inferred. That is, as the pipe line 1 is heated, the pipe line 1 tends to expand according to the linear expansion coefficient of the steel material, but the pipe line 1 buried in the ground is restrained by the surrounding earth and sand, and is free. Since the stretch is restricted, the pipe 1 is compressed and strained, and slips between the surrounding earth and sand against the restraining force to cause stretching.
[0016]
In the central part of the pipe line 1, since the pipe part extending from there to the both ends is restrained, displacement is difficult to occur, and since the restraining force is large, distortion due to slip is not released and a large compressive strain is produced. .
[0017]
On the other hand, in the part close to the terminal of the pipe line 1, since the pipe part from the terminal to the terminal is short, the binding force is small, and slip occurs between the pipe line 1 and the earth and sand, and the pipe line 1 has a direction of the terminal. A large displacement is generated in the direction of, so that the compression strain is released and the value becomes small.
[0018]
Thus, when the pipeline 1 is cooled after the temperature is raised to the maximum temperature, the compressive strain accumulated by the shrinkage of the pipeline 1 is rapidly reduced. Even if the compressive strain becomes zero, the pipeline 1 further tries to shrink the portion that has been stretched so far, and since it is restrained by the surrounding earth and sand, free shrinkage is restricted, Tensile distortion will occur. Then, slip occurs between the surrounding earth and sand against the restraint force, and the conduit 1 contracts.
[0019]
At this time, in the central part of the pipe line 1, the pipe part extending from there to both ends is restrained, so that the displacement is difficult to occur, and since the restraining force is large, distortion due to slipping is not released and a large pull is generated. Arise.
[0020]
On the other hand, in the part close to the terminal of the pipe line 1, since the pipe part from the terminal to the terminal is short, the restraining force is small, and a slip occurs between the pipe line 1 and the earth and sand with a relatively small force. A large displacement is generated in the direction of its center, thereby releasing the compressive strain, so that its value does not increase.
[0021]
Finally, a large tensile strain remains in the central portion of the pipeline 1 and a small tensile strain remains in the vicinity of the terminal, and the elongation does not disappear even if the pipeline 1 returns to room temperature due to the residual strain. Remains.
[0022]
Thus, in such a state, a large tensile strain remains in the vicinity of the center of the pipe line 1 and does not disappear even after a lapse of time. It is considered that the large tensile strain is concentrated on the pipe 1 and the pipe line 1 is broken.
[0023]
In cast iron pipes and the like, short pipes are connected by flanges, and the flanges cannot be displaced in the ground. Therefore, the pipes 1 do not expand even when heated, and the compressive strain generated there is When the path 1 is cooled, it is eliminated, and tensile strain does not remain. Further, in the case of a fume tube or the like, since the connecting portion can move relatively freely, distortion is rarely generated.
[0024]
On the other hand, in a pipe line system welded with steel pipe, the welded part of the steel pipe cannot be expanded and contracted, and it is only restrained by the frictional resistance caused by the ground pressing against expansion and contraction due to heat. If the pipe part limited for the purpose is separated from the pipe system, the extension cannot be stopped when a large compression strain is applied, and the tensile strain caused by cooling contracts due to the restraining force of the ground. Is suppressed, and finally a large tensile strain remains.
[0025]
And since the magnitude of the remaining tensile strain increases as the distance from the terminal of the separated pipe section becomes longer, if a lining is applied to a long pipe section, a large tensile strain remains due to heat in the lining work. However, the pipeline breaks due to the distortion. Therefore, in the pipe line system in which the steel pipe is welded as described above, there is a limit to the length that can be lined in one operation.
[0026]
The present invention has been made in view of such circumstances, and an object of the present invention is to provide a method capable of lining a sufficiently long pipeline portion in a single operation even in a pipeline system in which the aforementioned steel pipe is welded. It is what.
[0027]
[Means for Solving the Problems]
Thus, in the first invention, a window sufficient to introduce the lining material into the pipe portion is cut out on the pipe walls of both end portions of the pipe portion to be lined in the pipe line buried in the ground. The reinforcing material is interposed between the pipe lines on both sides of the window, the lining material is introduced into the pipe part from the window and heated, and the lining pipe part is cooled. It is characterized in that the pipe line in the excised part is restored by excising a nearby pipe line and performing a terminal treatment of the lining material.
[0029]
Moreover, 2nd invention cut | disconnects both the terminal parts of the pipe line part which should be lined in the pipe line embed | buried in the ground, and opposes the said pipe line part terminal part to the said pipe line part via a support member. Supporting the pipe part, introducing a lining material into the pipe part from the terminal and applying the lining by heating, cooling the lining pipe part, removing the support member, The terminal of the lining material is processed at the terminal of the pipe line portion, and the pipe line is restored.
[0030]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of the first invention, wherein 1 is a pipeline, and work holes 2 are cut at both ends of a pipeline portion 1a to be lined in the pipeline system this time, The working part 1b is exposed.
[0031]
A window 3 is cut out in the work portion 1 b in the work hole 2. The window 3 is preferably large enough to introduce the lining material 4 into the pipe line portion 1a and is preferably as small as possible.
[0032]
Since the working portion 1b has a reduced strength due to the opening of the window 3, and there is a risk of buckling when a compressive strain is applied in the subsequent heating process, a fixing tool is provided on both sides of the window 3 as shown in the drawing. It is preferable to attach a reinforcing member 6 between the fixtures 5 and prevent the pipe from buckling due to compressive stress during heating.
[0033]
FIG. 2 shows an embodiment of the second invention, in which the working portion 1b of the pipeline 1 exposed in the working hole 2 is cut, and the terminal portion of the pipeline portion 1a to be lined is It supports with respect to the pipe line part 1c which opposes via the supporting member 7. FIG. In addition, the terminal part of the pipe line part 1a can also be supported by the ground of the wall surface of the work hole 2 which opposes it with a suitable support means.
[0034]
Thus, in the state of FIG. 1 or FIG. 2, the lining material 4 is introduced into the pipeline portion 1a to be lined from the window 3 or the end of the cut pipeline portion 1a. As a method of introduction, a conventionally known method can be adopted. For example, it may be pulled in with a string inserted through the pipe line portion 1a, or the flexible lining material 4 is inserted into the pipe line portion 1a while being turned over by fluid pressure. You can also
[0035]
Then, a heating / pressurizing fluid such as pressurized water vapor, heating / pressurizing air, or hot water is fed into the lining material 4 inserted through the pipe line portion 1a, and the lining material 4 is heated and pressurized to form the lining material 4 Accordingly, the lining material 4 is pressed against the inner surface of the pipe line portion 1a by the action of heat and pressure to apply the lining.
[0036]
After cooling the lined pipe part 1a, in the first invention, the work part 1b in the work hole 2 is cut, and in the second invention, the support member 7 is removed, and at the end of the pipe part 1a. Terminal processing of the lining material 4 is performed, the excision part of the pipeline in the working hole 2 is connected, the pipeline system is restored, and the lining is completed.
[0037]
[Action]
In the present invention, in the first invention, the pipeline portion 1a to be lined and the pipeline portion 1c facing it are continuous, and in the second invention, the pipeline portion 1a faces the pipeline portion. Since it is supported with respect to 1c or the ground, even if the pipeline part 1a is heated and compressive strain is applied in the lining operation, the terminal part of the pipeline part 1a cannot be displaced in the extending direction.
[0038]
Accordingly, the compressive strain of the same degree is applied to all the portions of the pipeline portion 1a, but the pipeline 1 is not extended, and no displacement occurs in all locations regardless of the magnitude of the restraining force by the ground.
[0039]
Thus, when the heating process is completed and the pipe portion 1a is cooled, the compressive strain is eliminated and reduced. However, the compressive strain is zero when the temperature returns to room temperature because the compressive strain is not expanded during the previous heating. The tensile strain does not act beyond that.
[0040]
A curve A indicated by a broken line in FIG. 5 shows a relationship between temperature and strain in the present invention. That is, during heating, the compressive strain increases as the temperature rises, and increases to a value larger than the compressive strain in the conventional example. As the temperature decreases, the compressive strain decreases and finally the strain becomes almost zero, so that a large tensile strain does not remain.
[0041]
Further, since the pipe portion 1a does not expand and contract, the curve is drawn in conformity with the zero-displacement reference line at all positions in FIG. Accordingly, the magnitude of the distortion does not change in the terminal portion and the central portion of the pipe portion 1a, and the curve A in FIG. 5 draws a similar curve at all positions. Further, the magnitude of the distortion is not affected by the length of the pipeline portion 1a.
[0042]
【The invention's effect】
Therefore, according to the present invention, when the heating is performed in the lining process, the displacement of the pipeline portion 1a is prevented, so that the pipeline portion 1a does not extend due to heat. When the cooling is performed subsequent to the heating, only the compressive stress generated by the heating is eliminated, the pipeline portion 1a does not contract, and no tensile stress remains in the pipeline portion 1a. .
[0043]
In addition, the increase or decrease in compressive stress due to heating and cooling is affected only by temperature, and is not affected by the position in the pipeline portion 1a or the size of the restraining force due to the ground, so that the strain increases depending on the length of the pipeline portion 1a. The presence or absence of sheath expansion and contraction is not affected.
[0044]
Therefore, even if the lining is performed on the long pipe portion, a large tensile strain does not remain in the pipe portion, and the welded portion or the weak portion of the pipe does not break after the lining operation.
[Brief description of the drawings]
FIG. 1 is a side view showing the state of implementation of the first invention. FIG. 2 is a side view showing the state of implementation of the second invention. FIG. 3 is a state of testing the influence on the pipeline in the conventional method. FIG. 4 is a graph showing the state of expansion and contraction accompanying the temperature change of the pipe line. FIG. 5 is a graph showing the state of distortion accompanying the temperature change of the pipe line. 1 Pipe line 1a Pipe line part 1c to be lined Pipe part 3 Window 4 Liner 6 Reinforcing material

Claims (2)

A window sufficient to introduce the lining material (4) into the pipe part (1a) on the pipe walls of both ends of the pipe part (1a) to be lined in the pipe (1) buried in the ground (3) is cut and a reinforcing material (6) is interposed between pipes on both sides of the window (3), and a lining material (4) is introduced into the pipe part (1a) from the window (3). After heating and applying the lining and cooling the lined part (1a), the pipe (1) in the vicinity of the window (3) is excised, and the end treatment of the lining material (4) is performed. Lining method for underground buried pipelines, characterized in that the pipeline (1) of the damaged part is restored Cut both terminal portions of the pipeline portion (1a) to be lined in the pipeline (1) buried in the ground, and connect the terminal portion of the pipeline portion (1a) via the support member (7) supported against the pipe portion facing the pipe part (1a) (1c), heated to applying the lining is introduced lining material (4) from the terminal to the conduit portion (1a) within the lining After the pipe portion (1a) is cooled, the support member (7) is removed, and the end treatment of the lining material (4) is performed at the end of the pipe portion (1a) to restore the pipe (1). A lining method for underground conduits, characterized by

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