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Title:
EXPANDABLE INJECTION BOLT AND GROUTING METHOD USING SAME
Document Type and Number:
WIPO Patent Application WO/2005/073510
Kind Code:
A1
Abstract:
An expandable injection bolt (1A) comprising an expandable section (3), which has a tubular shape capable of applying an internal pressure form a rear end portion and expands in a radial direction when the internal pressure is applied, and an injection port forming section (9A) which opens an injection port (7) when the internal pressure is applied, wherein the expandable section (3) is expanded by the internal pressure so as to tightly adhere to ground, then the injection port forming section (9A) is caused to open the injection port (7), and a grout can be injected into the ground through the injection port (7) to reinforce the ground.

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Inventors:
Hirano, Kenkichi c/o DENKI KAGAKU KOGYO KABUSHIKI KAISHA (4-1 Yurakucho 1-chom, Chiyoda-ku Tokyo 55, 10084, JP)
Awa, Hiroshi c/o KFC Ltd (5-10 Shiba 2-chom, Minato-ku Tokyo 14, 10500, JP)
Application Number:
PCT/JP2005/001305
Publication Date:
August 11, 2005
Filing Date:
January 25, 2005
Export Citation:
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Assignee:
DENKI KAGAKU KOGYO KABUSHIKI KAISHA (4-1 Yurakucho 1-chome, Chiyoda-ku, Tokyo 55, 10084, JP)
KFC LTD. (2-17, Nishitenma 3-chome Kita-k, Osaka-shi Osaka 47, 53000, JP)
Hirano, Kenkichi c/o DENKI KAGAKU KOGYO KABUSHIKI KAISHA (4-1 Yurakucho 1-chom, Chiyoda-ku Tokyo 55, 10084, JP)
Awa, Hiroshi c/o KFC Ltd (5-10 Shiba 2-chom, Minato-ku Tokyo 14, 10500, JP)
International Classes:
E02D5/80; E21D20/00; E21D21/00; (IPC1-7): E21D20/00; E02D5/80
Domestic Patent References:
WO1997031177A1
Foreign References:
US4634317A
JP2003148098A
JP2003206698A
JP2000008796A
JPS6121300A
JPS58106499U1983-07-20
Attorney, Agent or Firm:
Watanabe, Keisuke (6th Floor, Mitsui Sumitomo Ginko Okachimachi Bld., 11-4, Taito 4-chom, Taito-ku Tokyo, 110-0016, JP)
Download PDF:
Claims:
C L A I M. S
1. An expandable injection bolt, comprising an expandable section, which has a tubular shape capable of applying an internal pressure from a rear end and expands in a radial direction when the internal pressure is applied, and an injection port forming section which opens an injection port when an internal pressure is applied.
2. The expandable injection bolt according to claim 1, wherein the expandable section has a structure with a pushin section formed by partly pushing a plastic deformable circular tube inwardly along the axial direction.
3. The expandable injection bolt according to claim 2, wherein the expandable injection bolt has the expandable section on at least its front end section, and the injection port forming section has a welded zone for sealing, which allows to open a front end of the expandable section to both sides from a pushin mouth of the pushin section and also to prevent the diameter from being expanded, and an embrittlement section which is disposed on the pushin section near the welded zone and broken by an internal pressure to open the injection port.
4. The expandable injection bolt according to claim 3, wherein the injection port forming section has a holding sleeve which is caulked to the external wall surface of the expandable section at a position corresponding to the embrittlement section and broken by the internal pressure to rupture the embrittlement section, thereby opening the injection port.
5. The expandable injection bolt according to claim 2, wherein the injection port forming section has an injection port which is previously formed in the expandable section and a stopper which closes the injection port and opens the injection port by the internal pressure.
6. The expandable injection bolt according to claim 2, wherein the injection port forming section has an injection port, which is previously formed in the expandable section, and a holding sleeve which is caulked to the external wall surface of the expandable section in close contact with the injection port and breaks the expandable section by an internal pressure to open the injection port.
7. The expandable injection bolt according to claim 1, wherein a sealing material is wound around the external wall surface of the expandable section.
8. The expandable injection bolt according to claim 1, wherein the rear end section is a mouth sleeve which opens in the axial direction.
9. The expandable injection bolt according to claim 1, further comprising a drill bit on its front end.
10. The expandable injection bolt according to claim 2, wherein the injection port forming section has a sleeve for a cap, which has the rear end attached to the front end of the expandable section, and a cap which closes the front end of the sleeve for the cap and separates from the sleeve for the cap when the internal pressure is applied.
11. The expandable injection bolt according to claim 10, further comprising a front end sleeve which is attached to the front end section of the expandable section, wherein the rear end section of the sleeve for the cap is attached to the front end sleeve.
12. The expandable injection bolt according to claim 10, wherein the sleeve for the cap and the cap are integrally formed, the connected section of them is formed thinner than other portions, and the connected section is broken to separate the cap from the sleeve for the cap when an internal pressure applied.
13. The expandable injection bolt according to claim 10, wherein the cap is formed of a synthetic resin and attached to embed into the sleeve for the cap.
14. The expandable injection bolt according to claim 11, further comprising a rear end sleeve which is attached to the rear end section of the expandable section, wherein the rear end section is provided with a mouth sleeve which has its rear end open in the axial direction.
15. The expandable injection bolt according to claim 2, comprising a rear end side expandable injection bolt section having an extension front end sleeve attached to the front end of the expandable section and a front end side expandable injection bolt section having an extension rear end sleeve attached to the rear end of the expandable section, wherein the rear end side expandable injection bolt section and the front end side expandable injection bolt section are connected with the inside spaces communicated through the extension front end sleeve and the extension rear end sleeve.
16. The expandable injection bolt according to claim 15, wherein at least one middle expandable injection bolt section, which has an extension front end sleeve and an extension rear end sleeve disposed on the front end and rear end of the expandable section, is connected between the rear end side expandable injection bolt section and the front end side expandable injection bolt section.
17. The expandable injection bolt according to any of claims 1 to 16, wherein the injection port forming section opens the injection port by a pressure higher than a minimum pressure required for the expansion of the expandable section.
18. A grouting method, comprising: using an expandable injection bolt, which has an expandable section having a tubular shape capable of applying an internal pressure from a rear end and expanding in a radial direction when the internal pressure is applied and an injection port forming section which opens an injection port when an internal pressure is applied; inserting the expandable injection bolt into ground; applying the internal pressure to the expandable injection bolt to expand the expandable section and to open the injection port; supplying a grout to the expandable injection bolt; and injecting the grout into the surroundings through the opened injection port.
19. The grouting method according to claim 18, wherein the injection port forming section of the expandable injection bolt has a sleeve, which is caulked to the external wall surface of the expandable section and ruptured by an internal pressure to open the injection port, and breaks the sleeve to open the injection port by applying a higher internal pressure after expanding the expandable section.
20. The grouting method according to claim 18, wherein the injection port forming section of the expandable injection bolt has a sleeve for a cap, which has the rear end section attached to the front end section of the expandable section, and a cap which closes the front end of the sleeve for the cap and is separated from the sleeve for the cap when the internal pressure is applied, and a higher internal pressure is applied after the expandable section is expanded to separate the cap from the sleeve for the cap to open the injection port.
21. A grouting method, comprising: using an expandable injection bolt, which has an expandable section having a tubular shape capable of applying an internal pressure through a mouth sleeve which is disposed at the rear end section and opens in the axial direction and expanding in a radial direction when the internal pressure is applied; inserting the expandable injection bolt into ground; applying the internal pressure to the expandable injection bolt to expand the expandable section; inserting a drilling tool through the mouth sleeve of the expandable injection bolt to form an injection port in the expandable injection bolt; supplying a grout to the expandable injection bolt; and injecting the grout to the surroundings through the injection port.
22. The grouting method according to claim 18, wherein an expandable injection bolt having a drill bit at the front end is used to drill a hole and inserted into the drilled hole at the same time.
23. A grouting method, comprising: using an expandable injection bolt, which has a body having a tubular shape capable of applying an internal pressure from a rear end and expanding in a radial direction when the internal pressure is applied and a cap with a sleeve which is separated into the cap and the sleeve when the internal pressure is applied and has the sleeve of the cap with the sleeve attached to the front end section of the body, inserting the expandable injection bolt into a drilled hole formed in ground; applying the internal pressure to the expandable injection bolt to expand the body; applying a higher internal pressure to separate the cap of the front end section; and supplying a grout into the expandable injection bolt to inject the grout into the drilled hole from the front end.
24. The grouting method according to any of claims 18 to 23, wherein types of grouts to be supplied to the expandable injection bolt are changed during the operation.
Description:
DESCRIPTION EXPANDABLE INJECTION BOLT AND GROUTING METHOD USING SAME

TECHNICAL FIELD The present invention relates to an expandable injection bolt, which is used to serve as a rock bolt and also a grout pipe, for a reinforcing construction of natural ground involved in, for example, a tunnel construction, and a grouting method using it.

BACKGROUND ART It is generally known that a slope of natural ground is drilled by a drilling machine, an grout pipe is inserted into the drilled hole to inject a grout such as cement milk or the like, a steel bolt type rock bolt is inserted into the drilled hole, the rock bolt is fixed by hardening of the grout, a bearing plate is pierced through the bolt section of the rock bolt which is externally protruded from the drilled hole and tightened by a nut <BR> to reinforce (e. g. , Japanese Patent Laid-Open Publication No.

2000-303480).

As a rock bolt which can be fixed without using a grout, there is known an expandable pipe type bolt which has a tubular shape with the front end sealed and a supply port at the rear end and has an expandable section at the middle section to expand in a radial direction by applying an internal pressure (e. g., Japanese Patent Publication No. 1990-520). This expandable pipe type bolt is inserted into a drilled hole, the internal pressure is applied, and the expandable section having a sectional shape that a plastic deformable circular tube partly pushed inside

expands in a radial direction to closely adhere to the drilled hole.

But, the steel bolt type rock bolt which is fixed by the grout has the following drawbacks.

To reinforce by injecting the grout into the ground surrounding the drilled hole, it is necessary to adequately seal the grout pipe and the drilled hole and supply the grout at a high pressure to sufficiently permeate the grout into the surrounding ground. But, this sealing is hard to perform, and it is also necessary to seal at the time of inserting the grout pipe and to remove the seal at the time of pulling out the grout pipe, resulting in poor workability. Especially, if there is spring water, even if the grout is injected, it is flown away before it hardens, resulting in difficulty in fixing the rock bolt. Besides, the natural ground is apt to easily deform before the grout hardens, and the natural ground is apt to have a large loosened area.

Meanwhile, the expansion bolt has an advantage of not having the above-described drawbacks because it can be fixed without using the grout.

But, if the surrounding ground is fragile, the expansion bolt has drawbacks that fixing power is insufficient even if the expandable section is expanded, and the reinforcing effect is apt to become insufficient. The drawbacks can be remedied by injecting the grout into the drilled hole by using the grout pipe in the same manner as the steel bolt type rock bolt and permeating the grout into the surrounding ground for reinforcing. But, there are the same drawbacks as those of the above-described steel bolt type rock bolt.

The present invention has been made in view of the above circumstances and provides to facilitate the reinforcement of surrounding ground by injection of a grout while maintaining the advantages of the expansion bolt.

SUMMARY OF THE INVENTION According to an aspect of the present invention, there is provided an expandable injection bolt, comprising an expandable section which has a tubular shape capable of applying an internal pressure from a rear end portion and expands in a radial direction when the internal pressure is applied, and an injection port forming section which opens an injection port when an internal pressure is applied.

The expandable injection bolt according to the present invention can tightly adhere the expandable section to the ground by expanding it when the internal pressure is applied and also can cause the injection port forming section to open the injection port. And, after the intimate contact to the ground and the opening of the injection port, the grout can be injected from the rear end of the expandable injection bolt to inject the grout into the surrounding ground via the open section.

As described above, the expandable injection bolt according to the present invention can seal the expandable injection bolt and the ground by the expandable section which expands to tightly adhere to the ground. Thus, even if there is spring water, it can be stopped without waiting for the injection and hardening of the grout. Besides, the grout can be prevented from leaking by virtue of the sealing, the work of injecting the grout is good,

and the surrounding ground can be reinforced by injecting the grout, so that the expandable injection bolt can be fixed in a good state even in fragile ground.

And, the expandable injection bolt according to the present invention is left as it is as the rock bolt after the grout is injected, so that the seal can be maintained even after the injection of the grout and the grout can be prevented from flowing out even in region of spring water. Besides, even if the surrounding ground is fragile, the expandable injection bolt according to the present invention can expand the expandable section to closely contact it with the ground and can provide an insufficient but certain degree of reinforcing effect without waiting for the injection and hardening of the grout, so that the natural ground can be retarded from becoming loose until the grout hardens.

The expandable injection bolt according to the present invention is roughly divided into one using a holding sleeve which is broken by the internal pressure as the injection port forming section, one using a cap and a sleeve for the cap which are separated by the internal pressure, and one using another structure. Their details and advantages will be described later.

The present invention provides a grouting method which comprises inserting the expandable injection bolt according to the present invention into ground, applying an internal pressure to the expandable injection bolt to expand the expandable section and to open the injection port, supplying the grout to the expandable injection bolt and injecting the grout into the surroundings via the opened injection port.

The grouting method according to the present invention is a construction method utilizing the characteristics of the expandable injection bolt of the present invention and can perform a ground reinforcing construction by injecting the grout while stopping spring water at an early stage, preventing the grout from leaking or flowing out, and preventing the natural ground from becoming loose until the grout hardens as described above.

And, the embodiments of the grouting method and other advantages according to the present invention will be described later.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view showing a first embodiment of the expandable injection bolt according to the present invention with the middle section omitted; Fig. 2 is a plan view of the expandable injection bolt shown in Fig. 1; Fig. 3 is a sectional view of the expandable injection bolt shown in Fig. 1; Fig. 4A and Fig. 4B are explanatory views of the front end section of the expandable injection bolt shown in Fig. 1, Fig.

4A is a magnified sectional view and Fig. 4B is a front view of the front end section; Fig. 5 is a view showing a drilled hole forming step; Fig. 6A and Fig. 6B are views showing a step of inserting the expandable injection bolt into a drilled hole, Fig. 6A is a view showing the expandable injection bolt inserted into the drilled hole, and Fig. 6B is a magnified sectional view of the

expandable section of Fig. 6A; Fig. 7A and Fig. 7B are views showing a step of expanding the expandable injection bolt, Fig. 7A is a view showing the expandable injection bolt having the expandable section expanded in the drilled hole, and Fig. 7B is a magnified sectional view of the expandable section of Fig. 7A; Fig. 8A to Fig. 8C are views showing a step of forming an injection port, Fig. 8A is a view showing the expandable injection bolt having the injection port opened in the drilled hole, Fig.

8B is a magnified perspective view showing the vicinity of the injection port forming section just before opening the injection port, and Fig. 8C is a magnified perspective view showing the vicinity of the injection port forming section having the injection port opened ; Fig. 9 is a view showing a step of injecting a grout; Fig. 10 is a view showing another example of the step of forming the injection port; Fig. 11 is a sectional view showing a second embodiment of the injection port forming section; Fig. 12 is a sectional view showing a third embodiment of the injection port forming section; Fig. 13 is a sectional view showing a fourth embodiment of the injection port forming section; Fig. 14 is a perspective view showing a second embodiment of the expandable injection bolt according to the present invention with the middle section omitted; Fig. 15 is an explanatory view when an internal pressure is regionally applied by a packer to open the injection port

forming section shown in Fig. 14; Fig. 16 is a perspective view showing a third embodiment of the expandable injection bolt according to the present invention with the middle section omitted; Fig. 17 is an external view showing a fourth embodiment of the expandable injection bolt according to the present invention; Fig. 18A and Fig. 18B are sectional views of a rear end section (grout supply side) and a front end section (the deepest side of the drilled hole) of the expandable injection bolt shown in Fig. 17; Fig. 19A to Fig. 19C are sectional views taken along A-A', B-B'and C-C'shown in Fig. 18A and Fig. 18B; Fig. 20 to Fig. 22 are sectional views of different structure examples of the injection port forming section consisting of a sleeve for a cap and the cap which can be used by the present invention; Fig. 23 is a sectional view of the front end section of the expandable injection bolt, which becomes a rear end when extended by connecting; Fig. 24 is a sectional view of the rear end section of the expandable injection bolt, which becomes a front end when extended by connecting ; Fig. 25A and Fig. 25B are explanatory views of the connection section of an expandable injection bolt which can be extended, Fig. 25A is a sectional view of the connection section of two expandable injection bolt sections, and Fig. 25B is an exterior view of the connection section of the two expandable injection bolt sections;

Fig. 26A and Fig. 26B are sectional views each showing a structure example of an attachment used attached to the expandable injection bolt; Fig. 27 is a view showing a drilled hole forming step; Fig. 28A and Fig. 28B are views showing a step of inserting the expandable injection bolt into a drilled hole, Fig. 28A is a view showing the expandable injection bolt inserted into a drilled hole, and Fig. 28B is a sectional view taken along A-A' of Fig. 28A; Fig. 29A and Fig. 29B are views showing a step of expanding the expandable injection bolt, Fig. 29A is a view showing the expandable injection bolt with the expandable section expanded within a drilled hole and Fig. 29B is a sectional view taken along A-A'of Fig. 29A; Fig. 30 is a view showing a step of forming the injection port, showing a state that a cap is separated by applying a higher internal pressure; Fig. 31 is a sectional view of the vicinity of a face in a tunnel construction using the grouting method of the present invention; and Fig. 32 is a front view of a face.

BEST MODES FOR CARRYING OUT THE INVENTION The present invention will be described with reference to the drawings.

Fig. 1 is a perspective view showing a first embodiment of the expandable injection bolt according to the present invention with the middle section omitted, Fig. 2 is a plan view of the

expandable injection bolt shown in Fig. 1, Fig. 3 is a sectional view of the expandable injection bolt shown in Fig. 1, and Figs.

4A and 4B are a magnified sectional view and a magnified front view of the front end section of the expandable injection bolt shown in Fig. 1.

As shown in Fig. 1 to Fig. 3, an expandable injection bolt 1A of this embodiment has a tubular shape provided with a mouth sleeve 2 disposed at a rear end and an expandable section 3 which is integral with and located in front of the mouth sleeve 2 and is configured to apply an internal pressure through the mouth sleeve 2.

The mouth sleeve 2 has a circular tubular shape which is substantially not expanded its diameter by an internal pressure and is open in the axial direction to communicate with the space within the expandable section 3. A screw section 5 is formed in the inner wall surface of the mouth sleeve 2, which is integrally connected to the expandable section 3 via an overlay weld 4. This screw section 5 is configured to connect equipment to be used for operations of supplying an internal pressure, supplying a grout and forming an injection port 7 (see Figs. 8A and 8C) by a drilling tool 6 (see Fig. 10) to be described later. The screw section 5 of the example shown in the drawing is formed in the inner wall surface of the mouth sleeve 2 but can also be formed in the external wall surface.

As apparent from the sectional view portion of Fig. 1, the expandable section 3 has a structure that a part of a circular tube is pushed inward along the axial direction to form a substantially C-shape cross section as a push-in section 8 which

is curved and pushed in. The expandable section 3 is radially expandable by applying an internal pressure to externally pushing the push-in section 8.

The expandable section 3 of the expandable injection bolt 1A is configured of a plastic deformable material which allows the above-described expansion and can keep the expanded state after the internal pressure is released. Specifically, metal such as iron, copper, aluminum or an alloy of them can be used, but it is generally desirably formed of a steel pipe because it is generally good in strength. And, it can also be formed of a flexible material such as rubber, synthetic resin or the like or a material using them as a base material depending on usage.

The expandable section 3 of this embodiment extends from the vicinity of the mouth sleeve 2 to the leading end, and the leading end of the expandable section 3 is formed as an injection port forming section 9A. The injection port forming section 9A is a portion to form the injection port 7 (see Figs. 8A and 8C) for injecting a grout to be described later into ground by the internal pressure, and the injection port forming section 9A of this embodiment is provided with a holding sleeve 10 which is caulked to the leading end of the expandable section 3 and rupturable, an embrittlement section (not distinguished from the other portions in the drawing) which is formed into the expandable section 3 to which the holding sleeve 10 is caulked and a welded zone 11 (see Fig. 3 and Figs. 4A, 4B) which seals the end opening of the expandable section 3.

A slit 12 is formed in either end of the holding sleeve 10, which is caulked to the leading end of the expandable section 3,

in position corresponding to that above a push-in mouth (substantially C-shaped discontinuous section) of the push-in section 8 formed in the expandable section 3. This slit 12 is not essential but it is desirable to dispose it in order to facilitate the adjustment of a rupture pressure of the holding sleeve 10 to be described later. The holding sleeve 10 can be formed of the same material as that configuring the expandable section 3 but may also be formed of a different material in order to adjust a rupture pressure to be described later.

Especially, as shown in Figs. 4A and 4B, the front end opening section of the expandable section 3 is closed by the welded zone 11 capable of preventing the diameter from being expanded when the push-in section 8 is pushed out. The welded zone 11 is formed to cover the end opening of the expandable section 3 while extending over the leading end of the expandable section 3 and the holding sleeve 10 along the substantially C-shaped form at the leading end of the expandable section 3 without connecting the push-in mouth of the push-in section 8. Therefore, when the internal pressure is applied to the expandable section 3, the leading end of the expandable section 3 is not caused to expand the diameter as indicated by arrows in Fig. 4B, but a force which opens the push-in mouth to both sides is applied, so that the holding sleeve 10 can be ruptured through the slits 12.

A part or whole of the leading end of the expandable section <BR> <BR> 3 to which the holding sleeve 10 is caulked forms the embrittlement section (not distinguished from other portions in the drawing) which is physically or chemically embrittled. This embrittlement section is a part configured to rupture or crack

easily by bursting when the holding sleeve 10 is broken so as to allow the injection port 7 (see Figs. 8A and 8C) to open.

For example, the embrittlement section can be formed by embrittling by work hardening such as drawing, embrittling by heating or cooling, embrittling by hydrogen gas or acetylene gas, embrittling by a carburizing treatment or an acid or alkali treatment, or by a combination of them. For example, the embrittlement section can be formed by work hardening by caulking the holding sleeve 10 and decreasing a diameter of the relevant part of the expandable section 3. The embrittlement section can also be formed by the heat used to form the welded zone 11.

In this embodiment, the vicinity of the bottom of the push-in section 8 which is embrittled by work hardening at the time of its formation is further work hardened by caulking the holding sleeve 10 until the expandable section 3 is decreased in diameter and also disposing the welded zone 11 so as to make it the embrittlement section. And, a large force is easily applied to the vicinity of the bottom of the push-in section 8 when the holding sleeve 10 is ruptured as described later. Therefore, it is desirable as a position of the embrittlement section.

The expandable injection bolt 1A of this embodiment has a sealing material 13 wound around the external wall surface of the expandable section 3 on the rear end and leading end sides. As the sealing material 13, cloth such as woven cloth or nonwoven cloth can be used other than an elastic material such as rubber or elastomer. If the sealing material 13 is an elastic material which can follow the expansion of the expandable section 3, the sealing material 13 can be closely contacted to the external wall

surface of the expandable section 3. But, where the cloth or the like is used, it is desirably wound loosely to allow the expansion of the expandable section 3. It is also desirable that the recess of the push-in section 8 can also be filled.

By disposing the sealing material 13, the expandable section 3 is brought into intimate contact with ground via the sealing material 13 as the expandable section 3 expands, so that a sealing property can be improved to additionally make sure the prevention of the grout from leaking and the stop of spring water.

In this embodiment, the sealing material 13 is disposed at two positions near the rear end and the leading end, but the sealing material 13 can be disposed near the rear end only or may be disposed on three or more positions.

The expandable injection bolt 1A of this embodiment is configured to have a series of expandable section 3 in front of the mouth sleeve 2, but the rear end and the leading end of the shown expandable section 3 can be formed as a mere tube material for an appropriate length, the expandable section 3 is disposed close to the leading end or the rear end only, or plural expandable sections 3 are connected by a tube material in the mutually communicated state in the axial direction, so that the expandable injection bolt 1A having the plural expandable sections 3 can be formed.

Then, one example of the grouting method of the present invention using the expandable injection bolt 1A described with reference to Fig. 1 to Figs. 4A, 4B will be described.

Fig. 5 to Fig. 9 are views showing a first embodiment of a procedure of the grouting method according to the present

invention. Fig. 5 is a view showing a step of forming a drilled hole; Fig. 6A and Fig. 6B are views showing a step of inserting the expandable injection bolt into the drilled hole, Fig. 6A is a view showing the expandable injection bolt inserted into the drilled hole, and Fig. 6B is a magnified sectional view of the expansion section of Fig. 6A; Fig. 7A and Fig. 7B are views showing a step of expanding the expandable injection bolt, Fig. 7A is a view showing the expandable injection bolt having the expansion section expanded in the drilled hole, and Fig. 7B is a magnified sectional view showing the expansion section of Fig. 7A; Fig. 8A to Fig. 8C are views showing a step of forming an injection port, Fig. 8A is a view showing the expandable injection bolt having the injection port opened in the drilled hole, Fig. 8B is a magnified perspective view showing the vicinity of the injection port forming section just before opening the injection port, and Fig. 8C is a magnified perspective view showing the vicinity of the injection port forming section having the injection port opened; and Fig. 9 is a view showing a step of injecting a grout.

In the drawings, the same reference numerals are allotted to the same members or positions as those shown in Fig. 1 to Figs. 4A, 4B.

As shown in Fig. 5, a drilled hole 15 having a prescribed depth is formed by a drill 14.

After the drilled hole 15 is formed, the expandable injection bolt 1A is inserted into ground by inserting its leading end (on the side of the injection port forming section 9A) first into the drilled hole 15 as shown in Fig. 6A. In this state, the expandable section 3 of the expandable injection bolt 1A is not

expanded as shown in Fig. 6A and Fig. 6B, and the expandable injection bolt 1A is inserted into the drilled hole 15 with a space around the expandable section 3 and the sealing material 13.

To insert the expandable injection bolt 1A into ground, it is not essential to form the drilled hole 15. For example, when ground is soft and clay or the like, the expandable injection bolt 1A can be inserted into the ground by directly inserting by an oil pressure machine or the like without forming the drilled hole 15.

Reference numeral 16 shown in Fig. 6A is an attachment for connection of a pressure feeding hose 17 (see Figs. 7A, 7B) to be described later and having a supply port 18 for supplying a pressure into the expandable injection bolt 1A, and the pressure feeding hose 17 can be connected in a state communicated with the supply port 18. The attachment 16 is attached by screwing a screw section 44 into the screw section 5 which is formed in the mouth sleeve 2 of the expandable injection bolt 1A. The attachment 16 may be attached before or after inserting the expandable injection bolt 1A into the drilled hole 15.

Then, the pressure feeding hose 17 is connected to the attachment 16 as shown in Fig. 7A, and an internal pressure is applied from the pressure feeding hose 17 to the expandable injection bolt 1A via the attachment 16. The internal pressure is applied as a fluid pressure. For example, it can be applied by a pressurized gas such as compressed air but it is desirable to use pressurized liquid by which a large pressure can be applied easily, and pressurized water is particularly desirable.

As shown in Fig. 7B, the expandable injection bolt 1A expands

the expandable section 3 in the radial direction by the internal pressure to intimately contact with the inner wall surface of the drilled hole 15, so that even if there is spring water from the drilled hole 15, it can be stopped. Especially, the sealing material 13 improves the closely adhered state at the position where the sealing material 13 is disposed, so that a water stop effect can be improved furthermore. Even if the surrounding ground is fragile, a certain degree of fixing power of the expandable injection bolt 1A can be obtained by the expansion of the expandable section 3.

It is desirable that the expandable section 3 is expanded by a pressure lower than that to open the injection port 7 (see Figs. 8A and 8C) in the injection port forming section 9A.

Specifically, it is desirable that it is expanded by a pressure higher than the minimum pressure required to obtain a desired expansion but lower than the pressure for opening the injection port 7 shown in Fig. 8A and Fig. 8C in the injection port forming section 9A. If the injection port 7 is opened before the expandable section 3 is completely expanded, the internal pressure leaks, and the internal pressure must be supplied (pressurized water is supplied) in a volume larger than the leaked volume, and the expanding work becomes difficult to perform.

The injection port 7 shown in Fig. 8A and Fig. 8C is opened in the injection port forming section 9A by expanding the expandable section 3 of the expandable injection bolt 1A to a required volume and further supplying a higher pressure.

A mechanism of opening the injection port 7 of the injection port forming section 9A will be described.

The leading end of the expandable section 3 of this embodiment is not subject to the diameter expansion as described with reference to Figs. 4A, 4B, but a force to open the push-in mouth of the push-in section 8 in both sides can be applied to rupture the holding sleeve 10 through the slits 12. Therefore, when a pressure higher than that required to obtain the expansion is supplied, the leading end of the expandable section 3 ruptures the holding sleeve 10 via the slits 12 to open to both sides as shown in Fig. 8B, the welded zone 11 deforms to follow the deformation of the holding sleeve 10, and the bottom of the push-in section 8 (see Fig. 1) is revealed. And, a force is applied by the internal pressure to the portion, which was the vicinity of the bottom of the push-in section 8, in the direction as indicated by the arrow in the drawing. Therefore, the force acts on the embrittlement section, which is formed near the bottom of the push-in section 8, is ruptured to open the injection port 7 shown in Fig. 8C. As described above, the vicinity of the bottom of the push-in section 8 is particularly suitable as the embrittlement section because it is embrittled by the work hardening at the time of forming and exposed to a large force when the holding sleeve 10 ruptures.

After the injection port 7 is opened, the internal pressure is released (pressurizing water is discharged) as required, a grout is supplied from the mouth sleeve 2 through the pressure feeding hose 17 with the attachment 16 attached or removed. As the grout, for example, a cement water suspension, a bentonite-water glass suspension, an aqueous water glass solution, a chromenigrin aqueous solution, an aqueous urea resin solution,

an aqueous acrylamide solution, an acrylate based aqueous solution, and an urethane resin solution can be used, and appropriate one can be selected depending on the characteristics and the like of ground.

To inject the grout, the gap between the ground and the expandable injection bolt 1A is sealed as described above to prevent the grout from leaking, and a desired grout injection region 19 can be obtained with certainty as shown in Fig. 9. After the injection is completed, the expandable injection bolt 1A is remained as it is as the rock bolt. Therefore, even if there is spring water, the grout can be prevented from flowing out by the expandable section 3 which has expanded for sealing, and the required area of ground can be improved without fail.

To inject the grout, a single type of grout may be injected, but plural types of grouts may be injected during the injection procedure by changing the types of grouts. As examples of the combination of plural types of grouts, a grout with good permeability is first injected to promote the injection into a wide area, then a grout having poor permeability and a high strength after hardening is injected to improve the circumferential strength; and a grout having a short hardening time (gel time) is injected first into a place where spring water is present to suppress the spring water, then a grout having a long hardening time is injected to permeate into the surroundings.

In the above examples, the injection port forming section 9A is provided with the holding sleeve 10 but can be configured without having the holding sleeve 10. In other words, the same configuration as described above may be adopted excepting that

the holding sleeve 10 is not disposed. But, it is desirable to configure such that the holding sleeve 10 is disposed to facilitate the adjustment of the pressure for forming the injection port 7 (see Fig. 8A and Fig. 8C), and when the forming pressure becomes larger than a prescribed pressure, the holding sleeve 10 ruptures to apply a large force to the embrittlement section.

Fig. 10 is a view showing another embodiment of the injection port forming step, wherein reference numerals indicate the relevant parts only.

In this embodiment, after the drilling step, the insertion step and the expanding step described with reference to Fig. 5 to Figs. 7A, 7B, the pressure feeding hose 17 and the attachment 16 are removed from the mouth sleeve 2 of the expandable injection bolt 1A, and the rod-like drilling tool 6 is inserted instead of them into the expandable injection bolt 1A from the mouth sleeve 2, an actuator 20 for operating the drilling tool 6 is attached to the mouth sleeve 2, and the leading end of the expandable injection bolt 1A is pushed by the drilling tool 6 to open the injection port 7. Thus, even if the injection port 7 cannot be formed in the injection port forming section 9A by increasing the pressure, the injection port 7 can be formed without fail. By employing this injection port forming step, the subsequent injection step shown in Fig. 9 can be performed by forcing to form the injection port 7 by the drilling tool 6 after the expansion step without previously disposing the injection port forming section 9A.

As the drilling tool 6, a rod-shape body having a sharp

leading end, a drill-shaped rod body or the like can be used other than the mere rod-shape body, and as the actuator, a hydraulic device or the like can be used. Where the drilling tool 6 is used, it is desirable that the opening of the rear end is large in the axial direction so as to facilitate the insertion into the expandable injection bolt 1A, but where the expandable injection bolt 1A has a small opening at the rear end, the opening can be enlarged by cutting the rear end after the expansion step to allow the insertion of the drilling tool 6. Especially, where the screw section 5 is formed in the mouth sleeve 2, the actuator 20 such as a hydraulic jack is screw connected to eliminate a reaction force, so that a push-in force can be acted accurately on the drilling tool 6.

Fig. 11 is a sectional view showing a second embodiment of the injection port forming section.

An injection port forming section 9B of this embodiment has the injection port 7, which is previously formed in the expandable section 3, closed by a stopper 21.

For the above-described injection port forming section 9B, when the stopper 21 is configured of, for example, a material having ductility smaller than that of the material configuring the expandable section 3 and the stopper 21 and the expandable section 3 are integrated by welding, a stress concentrates on the stopper 21 when the expandable section 3 is expanded so as to rupture it when the pressure is further increased, and the injection port 7 can be opened. Where the stopper 21 is formed as a screw type which is removed by a prescribed internal pressure and pressurized water is used to supply the internal pressure,

the stopper 21 is integrally formed with the expandable section 3 by a water-soluble adhesive, so that it can be ruptured by weakening the adhesion by the supplied pressurized water. The injection port forming section 9B based on the stopper 21 can be disposed easily at not only the leading end of the expandable section 3 but also near the rear end and the middle section of the expandable section 3.

Fig. 12 is a sectional view showing a third embodiment of the injection port forming section.

An injection port forming section 9C of this embodiment has a tubular lid material holding section 22, which is continuous from the leading end of the expandable section 3 and substantially free from diameter expansion due to an internal pressure, disposed, the opening at the leading end of the lid material holding section 22 determined as the injection port 7, and the injection port 7 sealed by a lid material 24 which is attached to the leading end of the lid material holding section 22 by an annular cap 23.

For the above-described injection port forming section 9C, the lid material 24 has strength to be broken by a prescribed internal pressure, and the internal pressure is increased after the expandable section 3 is expanded, in order to break the lid material 24, thereby enabling to open the injection port 7. The lid material 24 is easily broken through by the drilling tool 6 described with reference to Fig. 10, so that the injection port forming section 9C is especially suitable for another example of the injection port forming step described with reference to Fig.

10.

Fig. 13 is a sectional view showing a fourth embodiment of

the injection port forming section.

An injection port forming section 9D of this embodiment uses the same holding sleeve 10 as that described with reference to Fig. 1 to Figs. 4A, 4B and has the holding sleeve 10 caulked at a position corresponding to the injection port 7 previously formed in the expandable section 3 and the injection port 7 closed by the holding sleeve 10. The holding sleeve 10 is formed to have the slit 12 in both ends.

For the injection port forming section 9D, the portion where the holding sleeve 10 was caulked is prevented from expanding when the expandable section 3 is expanded, and the other expandable section 3 is expanded without largely expanding that portion, then the internal pressure is further increased to break the holding sleeve 10, thereby enabling to open the injection port 7. And, to assure the closed state of the injection port 7 until the holding sleeve 10 is broken, a packing (not shown) for sealing the injection port 7 may be interposed between the holding sleeve 10 and the expandable section 3. The injection port forming section 9D of this embodiment can be disposed easily not only at the leading end of the expandable section 3 but also near the rear end and the middle of the expandable section 3.

Fig. 14 is a perspective view showing a second embodiment of the expandable injection bolt according to the present invention with the middle section omitted; and Fig. 15 is an explanatory view when an internal pressure is regionally applied by a packer to open the injection port forming section shown in Fig. 14, and reference numerals indicate the relevant parts only.

For an expandable injection bolt 1B of this embodiment, a

leading end is closed by a closing cap 25, and plural injection port forming sections 9B (see Fig. 15) where the stopper 21 is fitted into the previously formed injection ports 7 are disposed with appropriate intervals in the axial direction at the middle section of the expandable section 3. The injection port forming sections 9B are same as that described with reference to Fig. 11 and open the injection ports 7 by increasing the internal pressure after the expandable section 3 is expanded and bursting the stoppers 21.

For the expandable injection bolt 1B which has the plural injection port forming sections 9B as shown in Fig. 14, the injection ports 7 (see Fig. 15) of all the injection port forming sections 9B are not opened simultaneously by the internal pressure, but they are opened with a time lag to cause the internal pressure to escape from the opened injection ports 7. Thus, all the injection ports 7 might not be opened. In order to prevent the internal pressure from escaping when the injection ports 7 are opened and to enable to open selectively the injection ports 7 partly, a packer 26 is preferably used to apply the internal pressure regionally as shown in Fig. 15.

In further detail, the internal pressure required for expansion of the expandable section 3 is applied to expand the expandable section 3 as shown in Fig. 7B. Thus, the push-in section 8 is extended, and the inner space of the expandable section 3 is increased to have a shape closer to a circular shape.

In this state, an injection pipe 27 (injection pipe with double packers) provided with the packer 26 on its front and rear shown in Fig. 15 is inserted into the expandable injection bolt 1B

through the mouth sleeve 2 shown in Fig. 14.

The packer 26 is a bag which can be expanded by a pressurized fluid such as pressurized water. With the injection port forming section 9B between the packers 26, the packers 26 are expanded by applying the fluid pressure to seal the front and rear of the expandable injection bolt 1B in its axial direction with the injection port forming section 9B intervened. In this state, the pressurized fluid is supplied into the region held between the packers 26 through the injection pipe 27 to regionally pressurize the inside of the expandable injection bolt 1B. Thus, the injection port 7 of the injection port forming section 9B at the position held between the packers 26 can be opened surely and selectively. The injection pipe 27 with the packers 26 can be moved within the expandable injection bolt 1B in the axial direction by releasing the pressure of the packers 26.

When the injection ports 7 are opened selectively from the plural injection port forming sections 9B as described above, all the plural injection ports 7 can be opened without fail but can also be opened selectively, and a different type of grout can also be injected through a different injection port 7. For example, only the injection port 7 closest to the leading end is opened to inject the grout, the grout in the expandable injection bolt 1B is washed out while it dose not harden or it is removed by drilling after it has hardened; then the injection port 7 closer to the rear end is opened, the leading end section is clogged as required, and a different type of grout is injected. Thus, different types of grouts can be injected in the axial direction of the expandable injection bolt 1B. The expandable section 3

of which expansion is not enough can be expanded furthermore by regionally pressurizing by means of the packers 26.

Fig. 16 is a perspective view of the third embodiment of the expandable injection bolt according to the present invention with the middle section omitted, and reference numerals indicate the relevant parts only.

An expandable injection bolt 1C of this embodiment has a drill bit 28 at its end.

When the drill bit 28 is disposed, the drilled hole 15 (see Fig. 5) is formed by the drill bit 28, and the expandable injection bolt 1C can be inserted into the drilled hole 15 at the same time.

Thus, the work time can be reduced.

Then, a fourth embodiment of the expandable injection bolt according to the present invention will be described.

Fig. 17 is a view showing the fourth embodiment of the expandable injection bolt according to the present invention.

Fig. 18A and Fig. 18B are sectional views of a rear end section (grout supply side) and a front end section (the deepest side of the drilled hole) of the expandable injection bolt shown in Fig.

17; and Fig. 19A to Fig. 19C are sectional views taken along A-A', B-B'and C-C'shown in Fig. 18A and Fig. 18B.

As shown in Fig. 17 and Figs. 18A, 18B, a expandable injection bolt 1D of this embodiment has the expandable section 3 and an injection port forming section 9E which is comprised of a sleeve 29 for a cap and a cap 30 which seals the leading end of the sleeve 29 for the cap.

And, a front end sleeve 31 and a rear end sleeve 32 are caulked to the front end and the rear end of the expandable section

3. The front end sleeve 31 has the rear end of the sleeve 29 for the cap of the injection port forming section 9E integrally connected by a welded zone 33, and the mouth sleeve 2 is integrally connected to the rear end sleeve 32 by a welded zone 34. The mouth sleeve 2 has the screw section 5 formed in its inner surface in the same way as the embodiment described with reference to Fig.

1 to Figs. 4A, 4B. Reference numeral 35 denotes a projection for attachment of a plate 36 (see Figs. 28A) which is used to fix the expandable injection bolt 1D to ground.

As apparent from the sectional view shown in Fig. 19B, the expandable section 3 of the expandable injection bolt 1D according to this embodiment has a substantially C shape having a push-in section 8 which is formed by pushing part of the circular tube to the inside along the axial direction so to partly push into the circular tube. Thus, the expandable section 3 is expandable in a radial direction by applying the internal pressure to the inside space to externally push out the push-in section 8.

As shown in Fig. 19A, the rear end section of the expandable section 3 has an exterior space between the push-in section 8 and the rear end sleeve 32 filled with a welded zone 37 to prevent the internal pressure from leaking to the outside and to suppress the diameter expansion at the time when the internal pressure is applied to the expandable injection bolt 1D. As shown in Fig.

19C, the front end section of the expandable section 3 has an exterior space between the push-in section 8 and the front end sleeve 31 filled with a welded zone 38 to suppress the diameter expansion.

The material configuring the expandable section 3 of the

expandable injection bolt 1D of this embodiment is the same as that of the expandable injection bolt 1A described with reference to Fig. 1 to Figs. 4A, 4B.

The injection port forming section 9E, which is comprised of the sleeve 29 for the cap and the cap 30 and attached to the front end section of the expandable injection bolt 1D of this embodiment, is an integrally formed body to have a thin wall between the sleeve 29 for the cap and the cap 30, so that the thin wall is broken by the internal pressure to separate the cap 30 from the sleeve 29 for the cap, and the front end section of the expandable injection bolt 1D can open the injection port 7.

The sleeve 29 for the cap and the cap 30 can be formed of the same material as that of the expandable section 3 and is desirably configured to separate the cap 30 from the sleeve 29 for the cap by a prescribed internal pressure, specifically an internal pressure higher than that at the time of the expansion of the expandable section 3. And, the connection with the expandable section 3 is not limited to the welding.

Fig. 20 to Fig. 22 show sectional views of different example configurations of the injection port forming section formed of the sleeve for a cap and the cap which can be used for the present invention.

The injection port forming section 9E of Fig. 20 has a synthetic resin cap 30 with a screw thread cut in its external wall screwed into a sleeve 29 for a metal cap with a screw thread cut in its interior wall. The injection port forming section 9E of Fig. 21 has the synthetic resin cap 30 with a screw thread cut in its external wall formed such that it is screwed into the sleeve

29 for a cap, so that the cap 30 is easily prevented from being damaged by an impact or the like during transportation or working.

The injection port forming sections 9E of Fig. 20 and Fig. 21 each are configured to separate the cap 30 from the sleeve 29 for the cap by utilizing the flexibility and elasticity of the synthetic resin configuring the cap 30. Fig. 22 shows a type that the front end section of the synthetic resin cap 29 with a screw thread cut in its exterior wall is formed thin, and a ball 39 is disposed in it, so that the ball 39 is externally ejected by the internal pressure to open the injection port 7. As the synthetic resin forming the caps 30 as shown in Fig. 20 to Fig. 22, for example, polyvinyl chloride, ABS (acrylonitrile-butadiene-styrene) resin, PET (polyethylene terephthalate), polycarbonate and the like can be used.

The expandable injection bolt 1D using the injection port forming section 9E comprised of the sleeve 29 for the cap and the cap 30 has a feature that it can be modified with ease so that it can be extended by connecting two or three or more of them.

This feature will be described with reference to Fig. 23 to Figs.

25A, 25B.

Fig. 23 is a sectional view of the front end section of the expandable injection bolt, which becomes a rear end side after the extension by connecting ; Fig. 24 is a sectional view of the rear end section of the expandable injection bolt, which becomes a front end side after the extension by connecting; and Fig. 25A and Fig. 25B are explanatory views of the connection section of the expandable injection bolt which can be extended, Fig. 25A is a sectional view of a connection section of two expandable

injection bolt sections, and Fig. 25B is an exterior view of the connection section of the two expandable injection bolt sections.

As shown in Fig. 23, an extension front end sleeve 40 with a screw thread cut is connected to the front end sleeve 31 of the expandable injection bolt 1D of Fig. 17 instead of the sleeve 29 for the cap and the cap 30 by the welded zone 33 to provide a rear end side expandable injection bolt section 1D'which becomes a rear end side after the extension by connecting. Meanwhile, as shown in Fig. 24, an extension rear end sleeve 41 with a screw thread cut corresponding to the screw thread of the above-described extension front end sleeve 40 is connected to the rear end sleeve 32 of another expandable injection bolt 1D instead of the mouth sleeve 2 by the welded zone 34 to provide a front end side expandable injection bolt section 1D"which becomes a front end side after the extension by connecting.

As shown in Fig. 25A, the extension front end sleeve 40 and the extension rear end sleeve 41 are secured by screws, so that the rear end side expandable injection bolt section 1D'and the front end side expandable injection bolt section 1D"are connected in a state that the inside spaces are communicated by passages 42,43 to configure a series of expandable injection bolt (not shown).

The expandable injection bolt 1D using the injection port forming section 9E which is configured of the sleeve 29 for the cap and the cap 30 can be modified easily so that it can be extended by connecting not only two of them but also three or more of them.

Specifically, the extension front end sleeve 40 is attached to the front end section of the expandable injection bolt 1D of

Fig. 17 instead of the sleeve 29 for the cap and the cap 30, and the extension rear end sleeve 41 is attached to the rear end section of the same expandable injection bolt 1D instead of the mouth sleeve 2 to provide as the middle expandable injection bolt section of the extension middle section. And, one or more middle expandable injection bolt section can be disposed between the rear end side expandable injection bolt section 1D'and the front end side expandable injection bolt section 1D"shown in Fig. 23 and Fig. 24 to extend to a desired length. According to the present invention, two types of extension front end sleeve 40 and extension rear end sleeve 41 are separately provided as the extension members, and the extending work is to simply connect the extension front end sleeve 40 and the extension rear end sleeve 41 by screwing, so that the work can be conducted at a worksite, and they can be transported to the worksite in the length before the extension.

Then, the grouting method according to the present invention using the expandable injection bolt 1D described with reference to Fig. 17 will be described with reference to Figs.

26A, 26B to Fig. 30.

Fig. 26A and Fig. 26B are sectional views each showing a structure example of an attachment used attached to the expandable injection bolt; Fig. 27 is a view showing a step of forming a drilled hole; Fig. 28A and Fig. 28B are views showing a step of inserting the expandable injection bolt into the drilled hole, Fig. 28A is a view showing the expandable injection bolt inserted into the drilled hole, and Fig. 28B is a sectional view taken along A-A'of Fig. 28A; Fig. 29A and Fig. 29B are views showing a step

of expanding the expandable injection bolt, Fig. 29A is a view showing the expandable injection bolt with the expandable section expanded within the drilled hole and Fig. 29B is a sectional view taken along A-A'of Fig. 29A; and Fig. 30 is a view showing an injection port forming step, showing a state that the cap is separated by applying a higher internal pressure.

As shown in Fig. 27, a drilled hole 15 is formed in ground.

To form the drilled hole 15, a drilling auger of a generally used drill jumbo or the like may be used.

After the drilled hole 15 is formed, the expandable injection bolt 1D which has the plate 36 inserted to the position of the projection 35 is inserted into the drilled hole 15 as shown in Fig. 28A so as to be inserted into ground from the front end side (the side of the cap 30). In this state, the expandable section 3 of the expandable injection bolt 1D is not expanded as shown in Fig. 28A and Fig. 28B and inserted into the drilled hole 15 in a state of having a space between the expandable section 3 and the inside wall of the drilled hole 15.

Then, as shown in Fig. 29A, the attachment 16 is attached to the mouth sleeve 2, a pressure feeding hose (not shown) is connected to the attachment 16, and the internal pressure is applied to the expandable injection bolt 1D. This internal pressure is applied as a fluid pressure. For example, pressurized gas such as compressed air can also be applied, but it is generally preferable to use pressurized liquid, which can apply a large pressure, and especially pressurized water.

As shown in Fig. 26A, this attachment 16 has a screw section 44 and can be attached to the expandable injection bolt 1D by

screwing the screw section 44 to the mouth sleeve 2 of Fig. 17.

The attachment 16 is provided with a supply port 18 for supplying a pressure into the expandable injection bolt 1D. A pressure feeding hose (not shown) can be connected in a state that the supply port 18 is communicated. The attachment 16 may be attached before or after the insertion of the expandable injection bolt 1D into the drilled hole 15. As shown in Fig. 26B, an attachment 16'not having the screw section 44 may be welded directly to the rear end sleeve 32 without using the mouth sleeve 2.

Even if there is spring water from the drilled hole 15, the expandable injection bolt 1D can stop it because the expandable section 3 is expanded in the radial direction by the internal pressure to intimately adhere to the inside wall of the drilled hole 15 as shown in Fig. 29B. And, even if the surrounding ground is fragile, the expandable injection bolt 1 is provided with a certain fixing power by the expansion of the expandable section 3.

It is desirable that the expandable section 3 is expanded by a pressure lower than the pressure of separating the cap 30 from the sleeve 29 for the cap. If the cap 30 is separated from the sleeve 29 for the cap before the expandable section 3 is expanded adequately, the internal pressure leaks through the opening, and it becomes necessary to supply the internal pressure (pressurized water) in a volume larger than that of the leakage, resulting in making the expansion work difficult.

After the expandable section 3 of the expandable injection bolt 1D is expanded to the required volume, a higher pressure is further supplied to separate the cap 30 from the sleeve 29 for

the cap as shown in Fig. 30, and the injection port 7 is opened at the front end of the expandable injection bolt 1D.

Then, if necessary, the internal pressure is released (the pressurized water is discharged), and the grout is supplied from the mouth sleeve 2 through the pressure feeding hose (not shown) with the attachment 16 attached or removed. This grout was described in the example of the grouting method using the expandable injection bolt according to the first embodiment.

To inject the grout, the gap between the ground and the expandable injection bolt 1D is sealed as described above, so that the grout can be prevented from leaking to the outside and can be injected to the deepest point in the drilled hole 15. The expandable injection bolt 1D is left as it is as the rock bolt after the injection is completed. Therefore, even if there is spring water, the grout can be prevented from leaking by the effect of sealing by the expansion of the expandable section 3, and a required region of ground can be improved without fail.

In this embodiment, the grout may be injected by using a single type of grout, but plural types of grouts can be injected by changing the types of grouts during the injection work. An example combination of plural types of grouts was as described in the example of the grouting method using the expandable injection bolt according to the first example.

Fig. 31 is a sectional view of the vicinity of a face in a tunnel construction using the grouting method of the present invention. Fig. 32 is a front view of the face, wherein 101 denotes the expandable injection bolts of the present invention, 102 denotes grout injection regions, and 103 denotes a face.

As shown in the drawing, the grouting method using the expandable injection bolts 101 of the present invention can be used for stabilization of ground of the face 103 in the tunnel construction, the reinforcement of the ceiling section near the face 103 and the reinforcement of an arch-like concrete leg section configuring the inside wall of the tunnel. In the tunnel construction, the expandable injection bolts 101 are inserted into the ground immediately after digging, and the grout is injected to stabilize the already tunneled ground and to stabilize the ground to be excavated.

The ground surface just exposed by excavating is apt to become loose. Therefore, the vicinity of the mouth of a drilled hole in which the expandable injection bolt 101 is inserted when the grout is injected becomes loose, and the grout is apt to leak.

But, according to the present invention, the expandable section can be expanded to intimately adhere to the inside surface of the drilled hole to seal as described above. At the same time, spring water can also be sealed, so that the work of the tunnel construction which is performed by repeating the excavation and the ground reinforcement can be made efficient considerably.