JP4808086B2 - Inner pipe device for double pipe double packer injection method - Google Patents

Description

  The present invention relates to an injection inner pipe device used for a double pipe double packer injection method used in a chemical solution injection method.

There is a chemical solution injection method as one of the ground improvement methods for the purpose of liquefaction of existing foundation structures and seismic reinforcement of foundation piles in soft ground.
In the chemical injection method, chemical injection by horizontal boring is performed in the vicinity of the target structure by constructing vertical boring, oblique boring, or a vertical shaft.
One of the chemical solution injection methods is a double pipe double packer injection method.

For example, the horizontal construction procedure of the double pipe double packer injection method is as follows.
1) Drill holes horizontally from the vertical shaft toward the ground, and perform straight-forward drilling to a predetermined depth and position.
2) Install the outer injection pipe in the countermeasure ground.
3) Cement bentonite is injected into the special sleeve packer attached to the built-in injection outer pipe using the injection inner pipe.
4) Inject the drug solution in the same way.

During such injection construction, an injection material injection phenomenon may occur at the injection port at the start of erection. In that case, as a countermeasure at the site, it is often the case that the amount of leakage of the injection material is measured and the injection material is supplementally injected later.
As an injection inner pipe used for general injection construction, a packer part is provided before and after the injection hole of the injection material, that is, a packer rubber that expands when the injection material is supplied and adheres closely to the injection outer tube (for example, patent) Reference 1).
Japanese Patent Laid-Open No. 9-143777

However, the conventional infusion tube has the following problems.
1) Injection material leaks.
2) Every time there is a leak, the amount of leak is measured, and the effort for supplementary injection with respect to the design injection amount increases. As a result, the cost increases.
3) The chemical material cannot be injected at a predetermined injection speed, and a long construction time is required. The next day's injection construction, gel time and quality of the improvement may also be affected.

As a cause of the leak, non-uniform expansion of the packer rubber of the injection inner pipe that is repeatedly used is considered as one factor.
Also, high water pressure of 20-30 kPa is sent and the packer rubber is expanded like a balloon to prevent the leakage of the injected material when injecting the chemical solution, but the conventional structure has a small contact area of the packer rubber with the outer injection tube For this reason, it is considered that the injection material has a structure that easily leaks.
Therefore, since the injection pressure increases as the depth at which the injection construction is performed, the leakage tends to occur if the contact area of the packer rubber with the injection outer tube is small.

  An object of the present invention is to prevent the leakage of the injection material by increasing the contact portion of the packer part with the outer injection tube in the injection inner tube for the double tube double packer injection method.

  In order to solve the above problems, the invention described in claim 1 is used in the double pipe double packer injection method, inserted into the outer injection pipe, and before and after the injection hole of the injection material. The injection inner tube having a packer portion that expands and deforms during supply includes a plurality of ring-shaped portions on the outer periphery of the packer portion that are inflated and deformed when the injection material is supplied and are in close contact with the injection outer tube.

Invention of Claim 2 is an injection | pouring inner tube apparatus for double pipe double packer injection construction methods of Claim 1, Comprising: These ring-shaped parts differ in the outer diameter before expansion deformation . It is characterized by.

Invention of Claim 3 is an injection | pouring inner tube apparatus for double pipe double packer injection construction methods of Claim 1, Comprising: These ring-shaped parts have the same outer diameter before expansion deformation. It is characterized by.

  According to the present invention, the plurality of ring-shaped portions on the outer periphery of the packer portion are expanded and deformed when the injection material is supplied and are in close contact with the injection outer tube. Thus, leakage of the injection material can be prevented.

Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.
[First Embodiment]
FIG. 1 shows a configuration of an embodiment to which the present invention is applied. 1 is an outer injection pipe, 11 is an injection hole, 12 is a check valve rubber sleeve, 2 is an injection inner pipe, 21 is an ejection hole, and 22 is an injection hole. Packer rubber (packer part) 23, 24 and 25 are ring rubbers (ring-like parts).

As shown in the drawing, an injection inner tube 2 inserted into an injection outer tube 1 having an injection hole 11 and a check valve rubber sleeve 12 is disposed before and after an injection hole 21 for an injection material such as cement bentonite or a chemical solution. Is provided with a packer rubber 22 that constitutes a packer portion that expands and deforms like a balloon by the injection pressure of the injection material when the injection material is supplied.
Ring rubbers 23, 24, and 25 forming three ring-shaped portions are integrally provided at intervals on the outer periphery of the packer rubber 22 before and after that.

These three ring rubbers 23, 24, and 25 are made of hard rubber that can be shrunk, and are integrally molded with the packer rubber 22 or retrofitted to the packer rubber 22.
In this embodiment, the three ring rubbers 23, 24, and 25 have different outer diameters. That is, the outer diameter of the ring rubber 23 on the side close to the ejection hole 21 is the smallest, the outer diameter of the next ring rubber 24 is larger than the ring rubber 23, and the outer diameter of the next ring rubber 25 is the largest. Yes.

FIG. 2 shows the expansion of the packer rubber 22 and the three ring rubbers 23, 24, and 25. That is, in a state where the injection inner tube 2 is inserted into the injection outer tube 1 built in the ground, the packer rubber 22 and the three ring rubbers 23, 24, and 25 are like balloons due to the injection pressure of the injection material. As shown in the figure, the three ring rubbers 23, 24, and 25 are brought into close contact with the inner peripheral surface of the injection outer tube 1, respectively.
In this way, in the front and rear packer rubbers 22, the three ring rubbers 23, 24, and 25 are in close contact with the inner peripheral surface of the injection outer tube 1, so that the seal against the injection material injected from the injection holes 21 is provided. However, the three ring rubbers 23, 24, and 25 can be performed in three stages in order, and the leakage of the injection material can be effectively prevented.
Further, the packer rubber 22 and the three ring rubbers 23, 24, and 25 can be easily replaced with the packer portion of the existing injection inner tube.

In the above, it is necessary to set the contact pressure of the three ring rubbers 23, 24, and 25 to the inner peripheral surface of the injection outer tube 1 to be higher than the injection pressure of the injection material to ensure a sufficient safety factor.
The contact pressure of the ring rubber 23 on the side close to the ejection hole 21 is the smallest with respect to the inner peripheral surface of the injection outer tube 1, and the contact pressure of the next ring rubber 24 is large against this ring rubber 23. By setting so that the contact pressure of the ring rubber 25 is maximized, the leakage of the injected material can be surely prevented most efficiently.
In addition, you may change the intensity | strength of a ring rubber according to a construction depth. Further, the thickness and interval of the ring rubber are set appropriately.

[Second Embodiment]
FIG. 3 shows the ring-shaped portion of the second embodiment. As shown in the figure, three ring rubbers 26 having the same diameter are integrally provided on the outer periphery of the packer rubber 22.
As described above, even with the three ring rubbers 26 having the same diameter, the seal for the injection material ejected from the ejection holes 21 is sequentially provided in three stages by the three ring rubbers 26 as in the first embodiment. This can effectively prevent leakage of the injection material.

In the above embodiment, the material of the packer portion and the ring-shaped portion is rubber. Any material may be adopted.
Further, the detailed shape, size, thickness, position, and number of the packer part and the ring-shaped part, for example, the ring-shaped part may be at least two or four or more.
The positions and structures of the injection holes and the ejection holes are also arbitrary. For example, the interval between the ring-shaped portions can be adjusted as appropriate.
Furthermore, it is needless to say that other specific detailed structures can be appropriately changed.

The structure of one Embodiment to which this invention is applied is shown, and is the partially broken side view which showed the time of insertion of the injection | pouring inner pipe | tube to an injection | pouring outer pipe | tube. It is the partially broken side view which showed the packer part expansion time of FIG. It is the enlarged view which showed the ring-shaped part of 2nd Embodiment.

Explanation of symbols

1 Injection outer pipe 11 Injection hole 12 Check valve rubber sleeve 2 Injection inner pipe 21 Injection hole 22 Packer part 23/24/25/26 Ring-shaped part

Claims (3)

Used in the double pipe double packer injection method, inserted into the injection outer pipe, before and after the injection hole of the injection material, in the injection inner pipe provided with a packer part that expands and deforms when the injection material is supplied,
An injection inner pipe device for a double pipe double packer injection method, comprising a plurality of ring-shaped parts that are expanded and deformed when an injection material is supplied and are in close contact with the outer injection pipe on the outer periphery of the packer part. The injection inner pipe device for a double pipe double packer injection method according to claim 1, wherein the plurality of ring-shaped parts have different outer diameters before expansion and deformation . The injection inner pipe device for a double pipe double packer injection method according to claim 1, wherein the plurality of ring-shaped parts have the same outer diameter before expansion and deformation .

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