JPH07107430B2 - How to insert a small diameter tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention utilizes aged seabed pipelines, land pipelines, and various other types of buried pipes to bury a plurality of small-diameter pipes. Related to the insertion technology.

<Prior art> When a buried pipe deteriorates due to corrosion or cracks, it causes an accident of leakage of a transported product when the buried pipe is used as a transportation pipe, and when the aged pipe is used as a covering material. Groundwater infiltrates into the area, causing various accidents.

In order to prevent such accidents, it is conceivable to lay multiple small-diameter pipes instead of aging pipes (aged pipes). However, it is becoming very difficult to lay a completely new route because it is very difficult to secure a new route and the construction cost is soaring.

Therefore, at present, various studies are being carried out on a technique for laying a small-diameter pipe by using an aged pipe.

As typical laying technology for this new pipe, there are two technologies: laying while pulling each small-diameter pipe on the tip side of the aging pipe, and laying technology that pushes the rear end of the small-diameter pipe by applying a propulsive force with a hydraulic jack. Exists.

<Problems to be Solved by the Present Invention> The following problems exist in the technology for laying replacement of aged pipe represented by the above examples.

(B) In the conventional laying replacement technology, laying multiple small-diameter pipes easily causes buckling because the diameter of each pipe is small, and also causes a large amount of frictional resistance between the contact surfaces of the pipes. Therefore, the laying work is very difficult.

Under these circumstances, it is now desired to develop a practical laying technique capable of smoothly laying a plurality of small-diameter pipes without causing buckling.

(B) In the case of a method of laying a small-diameter pipe in an aged pipe while drawing it, it is necessary to pass a pulling wire in advance between the start end and the rear end of the aged pipe prior to the drawing work of the small-diameter pipe. .

For this reason, it takes a lot of work for construction, and there is a risk that the pulling wire may damage the inner surface of the aged pipe.

(C) In the case of a method of laying a small-diameter pipe by pushing it into an old pipe, an excessive compression force may act on the new pipe to cause buckling.

In order to prevent buckling of the small diameter pipe, it is necessary to increase the diameter of the small diameter pipe, but the inner diameter of the aged pipe is limited, and the diameter cannot be increased.

Further, if the propulsive force of the small diameter pipe is reduced, the propulsion work cannot be performed smoothly.

Therefore, as the laying distance of the small diameter pipe becomes longer, the laying work becomes more difficult.

(D) In any of the above-mentioned conventional methods, the aging pipe must be finally removed, which not only complicates the construction but also increases the construction cost and prolongs the construction period.

<Object of the present invention> The present invention has been made in order to solve the above problems, and an object thereof is to provide the following method of inserting a small-diameter tube.

(A) A method for inserting a small-diameter pipe that allows a plurality of small-diameter pipes to be laid simultaneously and efficiently by a simple means.

(B) A method for inserting a small-diameter pipe that can prevent the occurrence of excessive stress and damage to the small-diameter pipe.

(C) A method for inserting a small-diameter pipe that enables effective use of the outer pipe without removing the outer pipe.

<Structure of the Present Invention> Hereinafter, one embodiment of the present invention will be described with reference to the drawings. In the present embodiment, a case will be described in which an outer pipe is an aged existing pipe.

First, each equipment used for laying a small diameter pipe will be described. (Figs. 1 and 2) <A> Sheath pipe A in the figure is an aged pipe.

Reference numeral 1 is a sheath tube for housing a plurality of small diameter tubes 2 therein.

The tip of the sheath tube 1 is closed by covering a cap 11 or the like.

The outer diameter of the sheath pipe 1 is slightly smaller than the inner diameter of the aged pipe A, and the outer circumference of the sheath pipe 1 has a spiral shape for the purpose of reducing the frictional resistance between the sheath pipe 1 and the aged pipe A. There is also a case where a protrusion is provided.

<B> The plug 3 is a plug that closes the base end of the sheath tube 1, and the plug 3 is a sealing material that is continuous with the outer peripheral surface facing the inner periphery of the sheath tube 1.
31 is provided and inserted into the proximal end opening of the sheath tube 1 to close the proximal end of the sheath tube 1.

The base end of the plug 3 is grounded to the reaction board 7.

Liquids 4 and 5 having the properties described below are enclosed in the inside of the sheath pipe 1 and between the peripheral surfaces of the sheath pipe 1 and the aged pipe A.

In order to seal the liquid 4 in the sheath tube 1, a hose 32 for supplying liquid is attached to the plug 3 so as to penetrate the plug 3 so that it can be externally fed by pressure using a pressure feed pump or the like.

<C> Enclosed liquid The liquid 4 sealed inside the sheath pipe 1 in the state where the small-diameter pipe 2 is housed is the liquid 5 sealed between the peripheral faces of the sheath pipe 1 and the aging pipe A.
A liquid having a relatively smaller specific gravity than that of

In this way, the specific gravity of the liquid outside the sheath tube 1 is set to be larger than that of the liquid 4 inside the sheath tube 1 because the weight of the sheath tube 1 is reduced by the difference in the specific gravity of the two liquids 4 and 5. And old pipe A
This is to reduce the frictional resistance with.

[Filled Liquid Inside Sheath Pipe] As the liquid 4 to be sealed inside the sheath pipe 1, for example, a liquid having a specific gravity of less than 1.0 can be used.

[Filled Liquid Outside Sheath Pipe] As the liquid 5 sealed between the peripheral faces of the sheath pipe 1 and the aged pipe A, for example, a rust preventive liquid having a specific gravity of about 1.0 can be used.

<D> Sheath tube pushing means 6 is a pushing device that applies a propulsive force to the sheath tube 1. For example, a jack or the like using fluid pressure can be adopted.

The base end of the pushing device 6 is installed on a reaction force wall or the like.

In the present invention, the following two pushing forces are used together as the pushing force for pushing the sheath pipe 1 into the deteriorated pipe A.

That is, the pushing force by the liquid pressure generated by increasing the pressure of the liquid 4 sealed in the sheath tube 1 and the mechanical pushing force by the pushing device 6.

The reason for using the two pushing forces together with the sheath tube 1 is as follows.
This is because the compressive stress generated by the mechanical pushing force on the sheath tube 1 and the tensile stress generated by the liquid pressure are canceled each other to avoid the stress fracture of the sheath tube 1.

Next, a method of remanufacturing an aged pipe will be described.

<A> Insertion of the sheath pipe The sheath pipe 1 with the tip closed is inserted from the end of the aged pipe A.

Then, a predetermined number of small-diameter pipes 2 to be laid are inserted into the sheath pipe 1.

At this time, both ends of each small diameter tube 2 are closed in advance so that the liquid 4 does not enter the small diameter tube 2.

Next, the plug 3 is inserted into the base end of the sheath tube 1 to form a sealed body.

<B> Pushing by Liquid Pressure At the same time when the continuous supply of the liquid 4 into the sheath tube 1 is started, the pushing device 6 is extended.

When the pressure of the liquid 4 in the sheath tube 1 rises, the pressure of this liquid 4 is supported by the reaction wall 31 and acts as the advancing force of the sheath tube 1.

In addition, the mechanical pushing force of the pushing device 6 is simultaneously applied to the sheath tube 1.
As a result, the sheath pipe 1 advances in the aging pipe A.

The liquid 5 is replenished between the peripheral surfaces of the sheath pipe 1 and the aged pipe A in accordance with the amount of advance of the sheath pipe 1 in the aged pipe A.

<C> Friction resistance when pushing the sheath tube The sheath tube 1 receives buoyancy due to the difference in specific gravity between the liquids 4 and 5 sealed inside and outside the sheath tube 1.

Therefore, when the sheath pipe 1 advances, the frictional resistance generated between the sheath pipe 1 and the aged pipe A becomes smaller than that in the state in which the buoyancy is not generated at all.

Thus, the sheath tube 1 accommodating the plurality of small diameter tubes 2 can be pushed in with a small pushing force.

<D> Stress generated in the sheath tube The sheath tube 1 has a tensile stress due to liquid pressure that tends to increase toward the distal end of the sheath tube 1 and a pushing device 6 that tends to increase toward the proximal end of the sheath tube 1. The compressive stress is generated by
In reality, the overlapping portions of these stresses cancel each other out and a stress distribution as shown in FIG. 3 is seen.

That is, a compressive stress that tends to decrease in the forward direction is generated in the latter half of the sheath tube 1, and a tensile stress that tends to increase in the forward direction occurs in the first half of the sheath tube 1. There will be places where no stress is generated on the way.

Therefore, the pressure of the liquid 4 and the pushing force of the pushing device 6 are adjusted so that one of the compressive stress and the tensile stress does not become excessive.

When the pushing of one sheath tube 1 is completed, the pushing device 6 is retracted, and a new sheath tube 1 and a small bore tube 2 are connected to the proximal ends of the sheath tubes 1 and the small bore tubes 2 by welding. To do.

Hereinafter, the above-described steps are repeated to push in the sheath tube 1 and the small diameter tube 2 while sequentially extending them.

After pushing the sheath tube 1 over the entire length of the deteriorated pipe A, the sheath tube 1
The blockage at the tip of the group is released and the regeneration work of the aged pipe A is completed.

In the present invention, the aged pipe A is used as a protective shell without being removed.

Further, the sheath pipe 1 may remain in the aged pipe A to serve as a protective shell for the inlet pipe, or the sheath pipe 1 may be removed.

<Other Embodiment 1> In the above embodiment, the case where the plug 3 and the sheath tube 1 are moved in parallel to give a pushing force to the sheath tube 1 has been described.
It is also possible to supply the liquid 4 into the hermetically sealed sheath tube 1 with the plug 3 inserted into the inner part and to lay the sheath tube 1 in the aged pipe A using only the pushing force of the liquid. Is.

<Other example 2> Although the said Example demonstrated the case where the existing pipe | tube body which deteriorated was utilized as an outer pipe | tube, after laying a new outer pipe | tube, several small diameter pipe | tubes are included in this new outer pipe | tube. It is also possible to lay the sheath tube 1 accommodating 2 therein.

<Effects of the Present Invention> Since the present invention is as described above, the following effects can be obtained.

(A) By enclosing a liquid having a property larger than the specific gravity of the liquid enclosed in the sheath pipe between the peripheral surfaces of the outer pipe and the sheath pipe, the frictional resistance between the sheath pipe and the outer pipe can be reduced.

Therefore, the sheath tube can be efficiently pushed in with a small pushing force.

(B) Since a plurality of small-diameter pipes are accommodated in the sheath pipe and pushed into the outer pipe, the small-diameter pipe can be laid without causing various stresses.

(C) By using the liquid pumping force and the mechanical pushing force together, it is possible to prevent the sheath tube from being excessively stressed, which causes buckling or tensile fracture.

Therefore, the laying distance of the sheath pipe can be considerably extended as compared with the conventional laying technology.

(D) Do not remove the outer tube, but use it as a protective shell for the sheath tube.

Therefore, the work of removing the outer tube as in the past is not required,
It is possible to reduce the construction period and the construction cost.

(E) The tubular body after regeneration has a double-tube structure of a sheath tube and an outer tube.

Therefore, the tubular body after regeneration becomes tough.

[Brief description of drawings]

1 is an explanatory view of an embodiment of the present invention. FIG. 2 is a sectional view taken along the line II-II of FIG. 1. FIG. 3 is an explanatory view showing a distribution state of stress generated in the sheath tube when the sheath tube is inserted.

Claims (1)

[Claims] 1. An outer tube constructed prior to the sheath tube, wherein a plurality of small-diameter tubes are housed inside the sheath tube, and a distal end and a proximal end of the sheath tube are closed to form a sealed body. Insert the liquid, seal the liquid in the sealed tube, and inject a liquid having a higher specific gravity than the liquid in the tube between the outer tube and the tube, and press the mechanical force and mechanical force of the liquid in the tube. A small-diameter pipe insertion method, in which the outer pipe is advanced in the pushing direction with buoyancy generated in the sheath pipe by applying a strong pushing force to the sheath pipe.