Drill hole backfilling device and drill hole backfilling method

Abstract

To provide a back filling device of drilling hole capable of surely discharging a filler into a drilling hole from a container without using a coating material.SOLUTION: A back filling device 1 of a drilling hole which uses bentonite and / or a bentonite-based material mostly containing bentonite as a filler 3 and back-fills a drilling hole 2 includes: a cylindrical container 7 comprising a double pipe of an outer pipe 5 and an inner pipe 6; a bag material 12 whose end part is fixed to an inner surface above the outer pipe 5, and which has a bag-like storage part 16 formed by being folded back from an opening 14 on a lower side of the inner pipe 6 toward an inner surface of an apex part 15 on an upper side; an openable / closable lid 11 arranged on a lower end of the outer pipe 5; and a filler discharge mechanism 17 which allows downward relative displacement of the inner pipe 6 with respect to the outer pipe 5 according to the opening of the lid 11 when the container 7 is conveyed to a predetermined position inside the drilling hole 2, and which allows the filler 3 filled in the bag-like storage part 16 to be discharged to the outside of the container 7.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to an apparatus for backfilling a borehole and a method for backfilling a borehole. [Background technology]

[0002] Conventionally, when selecting a disposal site for high-level radioactive waste, drilling surveys are carried out to confirm the geological structure, etc. The boreholes need to be sealed because they could become a pathway for radiation to migrate when the disposal site is actually in operation.

[0003] As one of the fillers used for blocking boreholes, the use of bentonite-based materials mainly containing bentonite, which has the property of swelling when it comes into contact with water, has been considered. From the viewpoint of workability, the use of pellets of bentonite compacted into small particle sizes, crushed material compacted into a plate shape and then finely crushed, etc. has also been considered. In the following description, bentonite and / or bentonite-based materials mainly containing bentonite, as well as pellets compacted into small particle sizes and crushed material compacted into a plate shape and then finely crushed, are collectively referred to as bentonite.

[0004] The plugging of the borehole is usually carried out by a device called a dump bailer, which transports bentonite contained in a container equipped with the dump bailer to the plugging point in the borehole, and then opens the discharge port of the container to discharge the bentonite.

[0005] Groundwater floods the borehole, and when the discharge port of the dump bailer container is opened, the groundwater comes into contact with the bentonite. This causes the bentonite to rapidly swell and clog the discharge port, which may make it impossible to discharge the bentonite into the borehole. In an experiment conducted by the inventors, it was confirmed that when the bentonite comes into contact with water, it rapidly swells, causing the discharge port of the container to become clogged.

[0006] It has been considered to equip the dump bailer with a mechanism that can forcefully push out the bentonite with strong pressure when such clogging occurs. However, the dump bailer is designed to fit through a narrow borehole, so its internal volume is originally limited. If complex functional parts are placed inside, the volume for containing the bentonite will become even more limited. On the other hand, if the size of the dump bailer is made larger within the allowable limit, the gap between the inner wall of the borehole and the outer surface of the dump bailer will be narrowed, resulting in problems with the dump bailer's movement up and down the borehole.

[0007] On the other hand, a method has been considered in which the bentonite is coated in advance with a water-insoluble natural resin to prevent clogging at the discharge port of the container. However, this method leaves the coating material, which is an organic impurity, in the area to be blocked in the borehole. If the remaining coating material is decomposed by microorganisms, gas may be generated, which may hinder the blockage.

[0008] Incidentally, various fluid transport technologies using containers similar to dump bailers have been proposed. A chemical liquid is used to prevent lost circulation in boreholes drilled for oil or metal exploration. One proposal is to use a cylinder to transport this chemical liquid, lower the cylinder to a specified position, and operate the lifting valve to dissipate the enclosed chemical liquid (see, for example, Patent Document 1). Another proposal is to lower a cylinder that serves both as a cement bailer and a container for storing measuring instruments to the bottom of a completed borehole, where the measuring instruments are buried in cement while the cement milk is dispersed (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Special Publication No. 2-9158 [Patent Document 2] JP 2006-112102 A Summary of the Invention [Problem to be solved by the invention]

[0010] However, the above-mentioned conventional techniques do not address the problem that when the bentonite comes into contact with groundwater during the plugging of the borehole, it swells rapidly, causing clogging of the discharge port of the container. In addition, it is necessary to avoid leaving any coating material, which is an organic impurity, at the plugging point in the borehole. If the coating material remains in the ground, it may generate gas through microbial decomposition, and the generated gas may hinder the plugging of the borehole.

[0011] The present invention has been made in consideration of the above, and aims to provide a borehole backfilling device and a borehole backfilling method that can reliably discharge filler material from a container into a borehole without using a coating material. [Means for solving the problem]

[0012] (1) To achieve the above-mentioned object, the present invention provides a borehole backfilling device for backfilling a borehole with bentonite and / or a bentonite-based material mainly containing bentonite as a filler, the device comprising: a cylindrical container consisting of a double tube of an outer tube and an inner tube; a bag material having a bag-shaped storage section whose end is fixed to the upper inner surface of the outer tube and which is formed by folding back from the lower opening of the inner tube toward the upper inner surface of the top; a lid that can be opened and closed and disposed at the lower end of the outer tube; and a filler discharge mechanism that allows downward relative displacement of the inner tube with respect to the outer tube when the lid is opened when the container is transported to a predetermined position within the borehole, and discharges the filler loaded in the bag-shaped storage section to the outside of the container.

[0013] (2) In addition, the bag material in the present invention that achieves the above object may be made of a foldable polyethylene material.

[0014] (3) In order to achieve the above object, the inner tube of the present invention may be made of polyvinyl chloride and the periphery of the opening on the lower side may be deburred.

[0015] (4) Furthermore, the filler discharge mechanism of the present invention for achieving the above object may include a stopper that is disposed within the drilled hole at the predetermined position and restricts downward movement of only the outer tube.

[0016] (5) Furthermore, the filler discharge mechanism of the present invention for achieving the above object may include a power source for causing relative downward displacement of the inner tube with respect to the outer tube.

[0017] (6) In the present invention for achieving the above object, the borehole may be a borehole provided in a radioactive waste disposal site.

[0018] (7) To achieve the above object, the present invention provides a method for backfilling a borehole using bentonite and / or a bentonite-based material mainly containing bentonite as a filler, the method comprising the steps of: fixing an end of a predetermined bag material to an upper inner surface of a cylindrical container formed of a double tube having an outer tube with a lid that can be opened and closed at a lower end and an inner tube that is disposed inside the outer tube and has an open lower end; and folding back the bag material from a lower opening of the inner tube toward an upper top inner surface to form a bag-like storage section; and folding the bag material formed in the bag-like storage section forming step. This method for backfilling a borehole includes the steps of: loading the filler into a storage section; transporting the container, which is a double tube consisting of the outer tube with its lower end closed by the lid and the inner tube with the filler loaded into the bag-like storage section inside the outer tube, to a predetermined position within the borehole; and a filler discharging step, when the container reaches the predetermined position within the borehole in the transporting step, allowing the inner tube to displace downward relative to the outer tube as the lid is opened, thereby discharging the filler loaded in the bag-like storage section into groundwater. Effect of the Invention

[0019] According to the present invention, it is possible to provide an apparatus and a method for backfilling a borehole, which can reliably discharge a filler material from a container into the borehole without using a coating material. [Brief description of the drawings]

[0020] [Figure 1] 2 is a schematic diagram showing a state in which the cover of the outer pipe in the backfilling device for a borehole according to an embodiment of the present invention is closed; FIG. [Diagram 2] 2 is a diagram illustrating a state in which the lower end of the outer pipe in the borehole backfilling device of FIG. 1 abuts against a stopper member in a borehole side casing. FIG. [Diagram 3] 2 is a schematic diagram showing the state in which the borehole backfilling device of FIG. 1 is lowered to a predetermined position in the borehole and the lid of the outer pipe begins to open. FIG. [Figure 4] 2 is a schematic diagram showing a state in which the backfilling device for a borehole in FIG. 1 is lowered to a predetermined position in the borehole, the lid of the outer pipe is opened, the inner pipe is displaced relative to the outer pipe, and the filler material is discharged. [Diagram 5] 2 is an enlarged view for explaining a lower end portion of an inner pipe in the borehole backfilling device of FIG. 1. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

[0022] FIG. 1 is a diagram showing a state where the cover of the outer pipe in the backfilling device 1 for a borehole according to an embodiment of the present invention is closed. Hereinafter, the backfilling device 1 for a borehole is abbreviated as the backfilling device 1 as appropriate. FIG. 2 is a diagram explaining the state where the lower end of the outer pipe in the backfilling device 1 comes into contact with the stopper member in the borehole side casing. FIG. 3 is a diagram showing a state where the backfilling device 1 descends to a predetermined position in the borehole and the cover of the outer pipe starts to open. FIG. 4 is a diagram showing a state where the backfilling device 1 descends to a predetermined position in the borehole, the cover of the outer pipe opens, the inner pipe is displaced relative to the outer pipe, and the filler is discharged. FIG. 5 is a diagram showing an enlarged view of the lower end part of the inner pipe in the backfilling device 1.

[0023] A backfilling device 1 according to an embodiment of the present invention is a device for backfilling a borehole 2 provided vertically from the ground surface with a filler 3. The borehole 2 is, for example, a borehole provided in a radioactive waste treatment facility, and its depth may reach approximately 300 m. Its diameter is usually 20 cm or less. The borehole 2 is prevented from collapsing by a casing 4, which is made by successively adding metal pipes of a specified length to reach the depth, and the shape at the time of excavation is maintained.

[0024] The backfilling device 1 has a cylindrical container 7 consisting of a double pipe, an outer pipe 5 and an inner pipe 6. The outer pipe 5 is a metal pipe, for example made of stainless steel, with an opening 8 at the lower end and an upper bottom 9 that is closed at the upper end. A hinge 10 is provided on the edge of the opening 8 at the lower end of the outer pipe 5. A lid 11 is provided on the opening 8 of the outer pipe 5, which can be opened and closed freely and rotates around the hinge 10 between a position that closes the opening 8 and a position that opens it.

[0025] An end 13 of a flexible bag material 12 is fixed to the inner surface near the upper bottom 9 above the outer pipe 5. Meanwhile, the inner pipe 6 has an opening 14 that is open at its lower end, and its upper bottom portion that is closed at its upper end forms a top portion 15. The inner pipe 6 is, for example, a so-called PVC pipe made of polyvinyl chloride. The bag material 12 hanging down from the inner surface near the upper bottom 9 of the outer pipe 5 is folded back toward the underside of the top portion 15 on the upper side of the inner pipe 6 to form a bag-shaped storage section 16.

[0026] The filler 3 is loaded into the bag-shaped storage section 16. The filler 3 is bentonite and / or a bentonite-based material that mainly contains bentonite. The filler 3 is, for example, in the form of approximately almond-shaped pellets, and may be a mixture of pellets of different sizes.

[0027] The outer tube 5, inner tube 6, bag material 12, and stopper member 19 described later constitute a filler discharge mechanism 17 that allows relative downward displacement of the inner tube 6 with respect to the outer tube 5 when the container 7 is transported to a predetermined position within the casing 4 of the borehole 2 and the lid 11 is opened, thereby discharging the filler 3 loaded in the bag-shaped storage section 16 into the groundwater.

[0028] The container 7 is suspended by wires 18 from a lifting device (not shown) installed on the ground at the upper bottom 9 of the outer pipe 5, and moves up and down inside the casing 4 of the borehole 2. A stopper member 19, which is a protruding piece, is provided on the inner circumference near the lower end of the casing 4. Note that the mode in which the stopper member 19 is provided is merely one example, and as will be described later, the function of the stopper member 19 can be achieved by controlling the wires 18 and a lifting device on the ground, without providing the stopper member 19.

[0029] The stopper members 19 protrude radially from the inner peripheral wall of the casing 4 toward the center and come into contact with the edge of the opening 8 of the outer tube 5 as it descends, restricting the downward movement of the outer tube 5. The lid 11, which was closed as shown in Figure 1, is opened as shown in Figure 3 by an opening / closing mechanism (not shown) which operates in response to the outer tube 5 coming into contact with the stopper members 19.

[0030] The position of the inner pipe 6 is not restricted by the outer pipe 5. Therefore, when the lid 11 is opened, the inner pipe 6 is displaced downward relative to the outer pipe 5 by its own weight as shown in FIG. 4. At this time, the filler 3 is discharged downward by its own weight from the opening 14 of the released inner pipe 6. If the wire 18 is used to move the outer pipe 5 upward abruptly for a short distance at the same time as the lower end portion of the outer pipe 5 abuts against the stopper member 19, the discharge of the filler 3 can be promoted. On the other hand, the depth of the outer pipe 5 can be controlled by a lifting device on the ground, and the wire 18 can be stopped at the timing when the wire 18 extends to a depth where the lower end portion of the outer pipe 5 abuts against the stopper member 19, thereby stopping the descent of the outer pipe 5. In this case, it is not necessary to provide the stopper member 19. In this case, the discharge of the filler 3 can also be promoted by using the wire 18 to move the outer pipe 5 upward abruptly for a short distance after the outer pipe 5 stops.

[0031] The bag material 12 is made of a material that is not stretchable, has a predetermined breaking strength, and is flexible enough to be bent easily at the opening 14, which is the outlet of the inner tube 6. For example, polyethylene is suitable for this material. Meanwhile, the peripheral edge of the opening 14 of the inner tube 6 is deburred and the corners are rounded, as shown in Figure 5. Therefore, the bag material 12 can slide smoothly against the peripheral edge of the opening 14 of the inner tube 6 without getting caught, and can deform without resistance.

[0032] At the same time that the lid 11 of the outer pipe 5 is opened, groundwater begins to soak the filler 3 from the opening 14 side of the inner pipe 6, and the filler 3 starts to swell. At this point, most of the upper part of the filler 3 is covered by the bag material 12 constituting the bag-shaped storage section 16, so it does not come into contact with the groundwater yet (Fig. 3). Therefore, while the inner pipe 6 moves downward and the bag-shaped storage section 16 is gradually rolled up downward near the opening 14, the upper part of the filler 3 that is at the rear from the opening 14 side is still free from swelling (Fig. 4). Therefore, swelling of the filler 3 does not start in the part of the bag-shaped storage section 16 located inside the inner pipe 6, and clogging of the filler 3 through the bag material 12 does not occur inside the inner pipe 6.

[0033] From this state, the filler 3 descends under its own weight, and the bag-shaped storage section 16 gradually rolls up and out, causing the filler 3 to swell from the portion that has left the bag-shaped storage section 16. At this point, the filler 3 is outside the inner pipe 6, and the swelling does not cause clogging within the inner pipe 6. Therefore, according to the backfilling device 1, the entire amount of the filler 3 loaded in the bag-shaped storage section 16 can be reliably discharged into the borehole 2 without causing clogging within the inner pipe 6. The discharged filler 3 descends through the groundwater, and backfilling of the area to be blocked within the borehole 2 proceeds.

[0034] Since the filler material 3 itself does not use a coating material that inhibits swelling, there is no risk of gas being generated by microbial decomposition, which is a concern when this type of coating material remains in the ground, or of this gas interfering with the blocking of the borehole.

[0035] As described above, the borehole 2 is, for example, a borehole provided in a radioactive waste treatment facility. Application of the backfilling device 1 of the present invention to such a case provides a promising solution to an important environmental problem.

[0036] Next, a method for backfilling a borehole using the above-mentioned backfilling device 1 and bentonite as a filler will be described. The backfilling method for a borehole includes a bag-shaped storage section forming step, a loading step, a transporting step, and a filler discharging step.

[0037] In the bag-like storage section forming process, an end 13 of a flexible bag material 12 is fixed to the inner surface above the outer tube 5 of a cylindrical container 7 consisting of a double tube made of an outer tube 5 having a lid 11 that can be opened and closed at its lower end, and an inner tube 6 that is placed inside the outer tube 5 and has an opening 14 at its lower end. The bottom side of the bag material 12 with the end 13 fixed in this manner is rolled up and folded back from the opening 14 of the inner tube 6 toward the inner surface of the top part 15 on the upper side, to form a bag-like storage section 16.

[0038] Next, in the loading step, the filler 3 is loaded into the bag-shaped storage section 16 formed in the bag-shaped storage section forming step.

[0039] Next, in the transportation process, the container 7 consisting of a double tube consisting of an outer tube 5 with its lower opening 8 closed by a lid 11 and an inner tube 6 with filler material 3 loaded into its internal bag-shaped storage section 16 is transported to a predetermined position within the borehole 2.

[0040] Next, in the filler discharge process, when the container 7 reaches a predetermined position within the borehole 2 in the above-mentioned transport process, the inner tube 6 is allowed to move downward relative to the outer tube 5 as the lid 11 is opened, and the filler 3 loaded in the bag-shaped storage section 16 is discharged into the groundwater.

[0041] According to this method for backfilling a borehole, the entire amount of the filler material 3 loaded in the bag-shaped storage section 16 can be reliably discharged into the borehole 2 without clogging the inner pipe 6. The reason why the filler material 3 does not clog the inner pipe 6 is as described above with respect to the backfilling device 1. This allows backfilling of the area to be blocked in the borehole 2 to proceed. In addition, since the filler material 3 itself does not use a coating material that suppresses swelling, there is no risk of gas generation due to microbial decomposition, which is a concern when this type of coating material remains in the ground, or of this gas hindering the blocking of the borehole.

[0042] The present invention is not limited to the above embodiment, and modifications and improvements within the scope of the present invention are included in the present invention. For example, in the above-mentioned filler discharge mechanism 17 in the backfilling device 1, when the container 7 reaches a predetermined position in the borehole 2, the inner tube 6 is displaced downward relative to the outer tube 5 by its own weight as the lid 11 is opened, but a power source for causing the inner tube 6 to be displaced downward relative to the outer tube 5 may be provided. As this power source, for example, a power source utilizing the fact that the space between the lower surface of the upper bottom part 9 of the outer tube 5 and the upper surface of the top part 15 of the inner tube 6 is in an airtight state due to the bag material 12 may be used. That is, it is also conceivable to provide a small high-pressure nitrogen container in this airtight space, and to push down the upper surface of the top part 15 of the inner tube 6 like a piston with the nitrogen pressure generated when the sealing of the high-pressure nitrogen container is released as the lower end of the outer tube 5 abuts against the stopper member 19. [Explanation of symbols]

[0043] 1 Backfilling device 2. Borehole 3 Filling material 4 Casing 5 Outer tube 6 Inner tube 7 containers 8 aperture 9 Upper base 10 Hinge 11 Lid 12 Bag material 13 End 14 Aperture 15 eclipse 16 Bag-shaped storage section 17 Filler discharge mechanism 18 Wire 19 Stopper member

Claims

1. A backfilling device for a borehole, which backfills a borehole using bentonite and / or a bentonite-based material mainly containing bentonite as a filler, A cylindrical container having a double tube including an outer tube and an inner tube; a bag material having an end portion fixed to an upper inner surface of the outer tube and a bag-shaped storage portion formed by folding back from an opening on a lower side of the inner tube toward an upper inner surface of a top portion of the inner tube; A freely opening and closing lid disposed at a lower end of the outer tube; a filler discharge mechanism that allows the inner tube to displace downward relative to the outer tube when the container is transported to a predetermined position within the borehole and discharges the filler loaded in the bag-shaped storage section to the outside of the container when the lid is opened.

2. 2. The borehole backfilling apparatus of claim 1, wherein said bag material is a foldable polyethylene material.

3. 3. The apparatus for backfilling a borehole according to claim 1, wherein the inner pipe is made of polyvinyl chloride and the periphery of the opening on the lower side is deburred.

4. The backfilling device for a borehole according to any one of claims 1 to 3, wherein the filler discharge mechanism is disposed in the borehole at the predetermined position and is provided with a stopper that restricts downward movement of only the outer pipe.

5. The backfilling device for a borehole according to any one of claims 1 to 4, wherein the filler discharge mechanism includes a power source for causing a downward relative displacement of the inner pipe with respect to the outer pipe.

6. The apparatus for backfilling a borehole according to any one of claims 1 to 5, wherein the borehole is a borehole provided in a radioactive waste disposal site.

7. A method for backfilling a borehole, comprising backfilling the borehole with bentonite and / or a bentonite-based material mainly containing bentonite as a filler, comprising: a bag-shaped storage section forming step of fixing an end of a predetermined bag material to an upper inner surface of the outer tube of a cylindrical container having a double tube with a lid that can be opened and closed at a lower end and an inner tube that is disposed inside the outer tube and has an open lower end, and folding back the bag material from a lower opening of the inner tube toward an upper top inner surface of the inner tube to form a bag-shaped storage section; a loading step of loading the filler into the bag-shaped storage portion formed in the bag-shaped storage portion forming step; a transport process for transporting the container, which is a double-pipe container consisting of the outer pipe whose lower end is closed with the lid and the inner pipe whose bag-shaped storage section is filled with the filler, to a predetermined position in the borehole; a filler discharge step of discharging the filler loaded in the bag-shaped storage section into groundwater by allowing the inner tube to be displaced downward relative to the outer tube when the container reaches a predetermined position in the borehole in the transport step and opening the lid; A method for backfilling a borehole, comprising:

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