JP7705227B2 - Ground reinforcement method - Google Patents

Description

The present invention relates to a ground reinforcement method in which long reinforcing pipes are cast into the ground in front of the tunnel face during excavation, and cement is injected from the long reinforcing pipes into the surrounding ground to reinforce the ground in front.

Conventionally, when reinforcing the ground, a method is known in which multiple steel pipes, which are ground reinforcing pipes, are connected in series and cast into the ground. For example, in the reinforcement in front of the face of a tunnel excavation work, as shown in FIG. 7, multiple steel pipes 220 are connected in series and long steel pipes 202 are cast toward the front upper side or outer periphery of the ground 201, and a consolidation material is injected from the driven long steel pipes 202 to form a consolidation area 203, thereby improving the ground of the ground 201. A long-length pre-support work 204 is performed by connecting multiple steel pipes 220 in series and casting long steel pipes 205 from the face forward of the ground 201, and a long-length mirror reinforcement work 206 is performed by injecting a consolidation material from the driven long steel pipes 205 to improve the ground of the ground.

When constructing the long-length pre-supporting work 204 and the long-length mirror reinforcement work 206, for example, in the tunnel space T, a steel pipe 220 with a drilling rod 211 inserted inside is mounted on the guide cell 209 of the drilling arm 208 of the drill jumbo 207, and the drilling machine 210 to which the drilling rod 211 is connected is advanced on the guide cell 209 to drive the steel pipe 220 into the natural ground 201 while drilling holes. Then, when the first steel pipe 220 (220a) and the first drilling rod are driven into the natural ground 201 up to the base, the subsequent second steel pipe 220 (220b) and the second drilling rod are connected, and in many cases, about four steel pipes 220 of about 3 m are connected to drive the long steel pipes 202, 205 (see Figures 7 and 8). After the long steel pipes 202, 205 are cast, the drilling rod 211 is removed and retrieved, and an injection pipe is inserted into the long steel pipes 202, 205 to inject a consolidating material such as silica resin, urethane, or cement into the inside and outside of the long steel pipes 202, 205 to reinforce the ground.

In this type of ground reinforcement work, workers must manually connect the steel pipes at high altitudes near the face, so in order to reduce the labor required, methods are being considered that use steel pipes that can be connected simply by pushing them in, as in Patent Documents 1 to 3, and connect the following steel pipes simply by mechanically pushing them in on the guide cell.

JP 2004-190758 A Patent No. 6112918 Patent No. 6486657

When driving long steel pipes into the ground, the drilling bit attached to the tip of the first steel pipe has a slightly larger diameter than the steel pipe because it needs to draw in the steel pipe to drive it in, so a gap is created between the outer circumference of the steel pipe and the wall of the drilled hole. If the gap at the mouth of the drilled hole is left as it is, the binder will leak from the gap into the tunnel space in front of the hole when it is injected, so it is necessary to apply caulking to the mouth.

In reality, this type of mouth caulking is done by workers climbing to a high position and manually pushing rags or caulking capsules (capsule-type adhesive) into the hole mouth after each drilling, which is dangerous and time-consuming work. For this reason, there is a need for a ground reinforcement method that can perform mouth caulking that is safe and has high construction efficiency.

The present invention has been proposed in light of the above problems, and aims to provide a ground reinforcement method that allows for highly safe and efficient caulking of the edge of the foundation.

The ground reinforcement method of the present invention is a ground reinforcement method in which, during tunnel excavation, long reinforcing pipes are cast by connecting the reinforcing pipes in series into the ground in front of the face, and a consolidation material is injected into the ground around the long reinforcing pipe to reinforce the ground in front, and is characterized by comprising the following steps: a first step of casting a terminal reinforcing pipe, which has a circumferential protrusion that can block the space between the outer circumferential surface and the drilled hole wall, at the end of the long reinforcing pipe; a second step of positioning a packer inside the terminal reinforcing pipe at a position deeper into the hole than the circumferential protrusion; a third step of injecting consolidation material into the inside of the packer and causing the consolidation material to seep out from the packer toward the mouth of the drilled hole to form a mouth caulking area; and a fourth step of injecting consolidation material deeper into the hole than the packer.
This allows the gap between the outer periphery of the end reinforcing pipe and the wall of the drilled hole to be blocked by the circumferential protrusion, eliminating the need for workers to climb to a high position and manually pack the opening with a rag or caulking capsule each time a hole is drilled. This allows for a safe and efficient caulking process.

The ground reinforcement method of the present invention is characterized in that, in the first step, with the terminal reinforcement pipe having been cast halfway, a centralizer that is provided in a guide cell and supports the terminal reinforcement pipe is lowered, the centralizer is moved to the rear of the circumferential protrusion so as not to interfere with the circumferential protrusion and then raised, the centralizer supports a position of the terminal reinforcement pipe rear of the circumferential protrusion, and the casting work of the terminal reinforcement pipe is resumed.
This makes it possible to prevent interference between the circumferential protrusion of the end reinforcing tube and the centralizer, and to prevent damage to the circumferential protrusion or the centralizer due to interference. Also, centering of the end reinforcing tube by the centralizer can be ensured.

The natural ground reinforcement method of the present invention is characterized in that the end reinforcing pipe has a plurality of circumferential protrusions provided at intervals in the axial direction.
According to this, the gap between the outer circumferential surface of the end reinforcing pipe and the drilled wall can be more reliably sealed by the partition formed by the multiple circumferential protrusions spaced apart in the axial direction. By providing multiple circumferential protrusions spaced apart in the axial direction, if the consolidation material gets into the gap between the circumferential protrusions, it is injected firmly and exclusively into the gap, and the mouth caulking is reliably performed.

The natural ground reinforcement method of the present invention is characterized in that the circumferential protrusion of the end reinforcement pipe is formed in a tapered shape that gradually increases in diameter toward the rear end.
This allows the circumferential projection to be smoothly inserted into the drilled hole, ensuring that the gap between the outer circumferential surface of the end reinforcing tube and the wall of the drilled hole is closed.

The ground reinforcement method of the present invention allows for highly safe and efficient caulking of the mouth of the tunnel.

4A to 4E are process explanatory diagrams illustrating the first half of the natural ground reinforcement method according to an embodiment of the present invention. 4A to 4E are process explanatory diagrams illustrating the latter steps of the natural ground reinforcement method according to an embodiment. 1 is a perspective view showing the rear end periphery of a terminal reinforcing pipe and a terminal cap used in a natural ground reinforcement method according to an embodiment. FIG. 5A and 5B are schematic explanatory views illustrating a process of forming a mouth caulking region around the rear end of an end reinforcement pipe. 13 is a perspective view showing the rear end periphery and the terminal cap of another example of a terminal reinforcing pipe used in the natural ground reinforcement method of the embodiment. FIG. 5A and 5B are schematic explanatory views illustrating a process of forming a mouth caulking region around the rear end of an end reinforcement pipe in another example. An explanatory diagram showing long-length pre-support work and mirror reinforcement work in tunnel excavation work. FIG. 2 is an explanatory perspective view illustrating the connection of a second steel pipe to a first steel pipe that has already been cast.

[Embodiment of ground reinforcement method]
The natural ground reinforcement method according to an embodiment of the present invention is a natural ground reinforcement method in which reinforcing pipes 10, 10a are connected in series to cast a long reinforcing pipe 20 into the natural ground in front of the tunnel face during excavation, and a consolidation material is injected into the natural ground around the long reinforcing pipe 20 to reinforce the natural ground in front, and during construction, as shown in Fig. 1(a), for example, the natural ground reinforcement pipe 10 is cast into the natural ground 51 from the face of the natural ground 51 where sprayed concrete 52 is provided. Note that the natural ground reinforcement pipe 10 is preferably a steel pipe, but it is also possible to use a reinforcing pipe made of other materials such as resin.

When driving the reinforcing pipe 10, for example, a drilling device is used, which has a guide cell 11 attached to the arm of a drill jumbo, and a drilling machine 12 mounted on the guide cell 11 so that it can move forward and backward (see Figure 1). A centralizer is provided on the guide cell 11 to support the reinforcing pipe 10 attached to the drilling machine 12 from below. In the illustrated example, a fixed centralizer 13 is fixed at the leading position of the guide cell 11, and a movable centralizer 14 is provided to move forward and backward in a specified area on the guide cell 11.

A drilling rod is inserted inside the reinforcing pipe 10 (not shown), and the drilling bit at the head of the drilling rod is engaged with the leading reinforcing pipe 10 via a casing shoe at the tip of the leading reinforcing pipe 10. This engagement is achieved by rotating the drilling machine 12 forward and disengaged by rotating it in the reverse direction. In other words, if the reinforcing pipe 10 that has already been driven into the natural ground 51 is the leading pipe, the drilling bit is engaged with the tip of the reinforcing pipe 10 of the leading pipe, and the drilling rod is inserted into the reinforcing pipe 10. Figure 1(a) shows a state in which multiple reinforcing pipes 10 consisting of leading pipes and intermediate pipes have already been connected and driven into the natural ground 51, and the end portion of the reinforcing pipe 10 of the intermediate pipe protrudes outside the natural ground 51 from the drilling hole 53.

The reinforcing tubes 10 are structured so that the following reinforcing tube 10 is pushed into the preceding reinforcing tube 10 to connect and connect them. For example, the reinforcing tube 10 is configured by fitting an engaging member formed in a roughly C-shape to the outer periphery of the rear end, and forming an engaging groove on the inner periphery of the tip into which the engaging member is fitted from the inside. The leading reinforcing tube 10 and the trailing reinforcing tube 10 are connected by pushing the tip of the trailing reinforcing tube 10 so that it fits into the outside of the rear end of the leading reinforcing tube 10 to slightly reduce the diameter of the engaging member, and then elastically restoring the engaging member to its original diameter at the groove position of the trailing reinforcing tube 10 and fitting it into the fitting groove.

In Figures 1(a) and (b), a terminal reinforcing pipe 10a, which has a structure for connecting and connecting by pushing in the same way as the reinforcing pipe 10, is brought close to the reinforcing pipe 10 of the preceding intermediate pipe that has already been cast into the natural ground 51 by centering it with a fixed centralizer 13 and a movable centralizer 14, and the following terminal reinforcing pipe 10a is pushed into and connected to the reinforcing pipe 10 of the intermediate pipe. The terminal reinforcing pipe 10a connected to the intermediate pipe is cast into the deep side of the natural ground 51 together with the reinforcing pipe 10 of the leading pipe and the reinforcing pipe 10 of the intermediate pipe by drilling holes with a drilling bit.

The end reinforcing pipe 10a, like the reinforcing pipes 10 of the leading pipe and intermediate pipe, has a consolidation material discharge hole 102a formed in the peripheral wall 101a, and a circumferential protrusion 103a is provided at the rear that can close the gap between the outer periphery of the peripheral wall 101a and the drilling wall 54 of the drilling hole 53 (see Figures 1 to 4).

The circumferential protrusion 103a in Figs. 1 to 4 is formed of a protrusion that protrudes from the peripheral wall 101a in a flange-like shape, and is provided in multiple axially spaced relation, with three circumferential protrusions 103a provided at intervals in the illustrated example. The circumferential protrusions 103a of the protrusions are provided, for example, by welding to the peripheral wall 101a. In addition, the tip of the circumferential protrusion 103a on the inner side of the hole is preferably provided at a distance of about 80 cm from the rear end of the terminal reinforcement pipe 10a, and since the casting of the terminal reinforcement pipe 10a is completed with the terminal reinforcement pipe 10a protruding outwardly by about 15 to 30 cm from the sprayed concrete 52, it is preferable that the multiple circumferential protrusions 103a, such as three, are provided within a range of about 40 to 80 cm from the rear end of the terminal reinforcement pipe 10a.

Then, when the casting of the terminal reinforcement pipe 10a progresses and the circumferential protrusion 103a of the terminal reinforcement pipe 10a reaches close to the centralizer, the centralizers supporting the terminal reinforcement pipe 10a (in this example, the fixed centralizer 13 and the movable centralizer 14) are lowered while the terminal reinforcement pipe 10a is cast partway, and the centralizers are moved to the rear of the circumferential protrusion 103a so as not to interfere with it, and then raised. The centralizers support the position of the terminal reinforcement pipe 10a behind the circumferential protrusion 103a, and the casting of the terminal reinforcement pipe 10a is resumed (see Figures 1(c) to (e)).

In the example of Figures 1(c) to (e), the guide cell 11, which is provided with a centralizer consisting of a fixed centralizer 13 and a movable centralizer 14, is lowered, the guide cell 11 is moved and raised so that the centralizer is positioned behind the circumferential protrusion 103a, and the guide cell 11 is raised so that the centralizer supports the position behind the circumferential protrusion 103a of the terminal reinforcement tube 10a. Note that in Figure 1(d), for convenience of illustration, the guide cell 11 is shown in a state where it is fully lowered, but when performing this process in actual construction, since there is a drilling rod inserted into the terminal reinforcement tube 10a, it is sufficient to lower the guide cell 11 slightly so that the circumferential protrusion 103a can pass through. If this is difficult, the drilling rod may be removed from the drilling machine 12 on the guide cell 11, and after the centralizer is positioned to support the position behind the circumferential protrusion 103a of the terminal reinforcement tube 10a, the drilling rod may be reattached to the drilling machine 12. The centralizers 13 and 14 may also be configured to descend relative to the guide cell 11. Furthermore, by devising a shape that allows the circumferential projection 103a and the centralizers 13 and 14 to pass without much interference, such as by making the front surface of the circumferential projection 103a an inclined surface that slopes forward, it is possible to allow the centralizers 13 and 14 to pass directly without the process of lowering and raising them.

After resuming the installation of the end reinforcement pipe 10a, the circumferential protrusion 103a of the end reinforcement pipe 10a enters the drilled hole 53, and the end reinforcement pipe 10a is installed up to a predetermined position where the circumferential protrusion 103a is positioned so as to close the gap between the outer circumferential surface of the peripheral wall 101a and the drilled hole wall 54, completing the installation of the end reinforcement pipe 10a. The installed end reinforcement pipe 10a forms the end of the long reinforcement pipe 20 (see Figure 2 (a)). The drilling rods inserted in the end reinforcement pipe 10a and the reinforcement pipes 10 of the leading pipe and intermediate pipe are removed and collected.

The cast terminal reinforcement pipe 10a is fitted with a consolidation material injection tool 30 (see Figs. 2(b) and (c)). The injection tool 30 is composed of a terminal cap 31 that is attached by external fitting to the rear end of the terminal reinforcement pipe 10a in a freely detachable manner, a packer injection hose 32 that is inserted into the terminal reinforcement pipe 10a so as to penetrate the base plate 311 of the terminal cap 31, a packer 33 that is attached to the tip of the packer injection hose 32 and placed inside the terminal reinforcement pipe 10a, and a rear injection hose 34 that is inserted into the long reinforcement pipe 20 so as to penetrate the base plate 311 of the terminal cap 31. Note that, for simplification, only one rear injection hose 34 is shown in the drawing, but in actual construction, multiple rear injection hoses 34 of different lengths are used according to the length of the long reinforcement pipe 20, and are often arranged so that stepwise injection can be performed for each injection area in the injection process behind the packer 33.

As shown in Figures 2(c) and 4(a), the packer 33 is placed inside the terminal reinforcing tube 10a at a position closer to the inner hole than the circumferential protrusion 103a, and is preferably placed away from the inner hole tip of the circumferential protrusion 103a in the axial direction of the terminal reinforcing tube 10a. For example, if the three circumferential protrusions 103a are placed within a range of 40 to 80 cm from the rear end of the terminal reinforcing tube 10a, the packer 33 is placed about 1 m from the rear end of the terminal reinforcing tube 10a toward the inner hole.

In this state, the consolidation material 41 is injected into the packer 33, and the consolidation material 41 seeps out from the packer 33 to the mouth side of the drilled hole 53 to form the mouth caulking area 42 (see Figures 2 (c), (d), and 4 (b)). It is preferable to use a packer 33 that allows the consolidation material 41 to seep out only to the mouth side. For example, it is preferable to use a packer 33 in which the inner side of the hole is made of a material such as nylon, vinyl, or rubber that does not allow the consolidation material 41 to seep out, and the mouth side is made of a material such as cloth that allows the consolidation material 41 to seep out.

The peripheral wall 101a of the terminal reinforcement pipe 10a between the packer 33 arranged inside the terminal reinforcement pipe 10a and the tip of the multiple circumferential protrusions 103a on the inner side of the hole has a consolidation material discharge hole 102a. When the consolidation material 41 is injected into the inside of the packer 33, the packer 33 expands with the filling of the consolidation material 41, and the consolidation material 41 that seeps out from the packer 33 is injected into the inside of the terminal reinforcement pipe 10a on the mouth side of the drilled hole 53, and is discharged from the discharge hole 102a of the peripheral wall 101a between the packer 33 and the tip of the circumferential protrusions 103a on the inner side of the hole, and is injected into the drilled hole 53 and the ground 51 to form the mouth caulking area 42.

After the mouth caulking area 42 is formed, the consolidation material 43 is injected from the rear injection hose 34 inserted inside the long reinforcing pipe 20. The consolidation material 43 is injected into the inside of the long reinforcing pipe 20 on the inner side of the hole from the mouth caulking area 42, and is also discharged from the discharge hole 102a of the end reinforcing pipe 10a and the discharge holes formed in the intermediate pipe and the leading pipe reinforcing pipe 10 that constitute the long reinforcing pipe 20 to the outside of the long reinforcing pipe 20 and injected into the drilled hole 53 and the ground 51, forming the consolidation area 44 in a state where leakage of the consolidation material 43 is prevented in the mouth caulking area 42 (see FIG. 2(e)).

According to the ground reinforcement method of this embodiment, the gap between the outer surface of the terminal reinforcement pipe 10a and the drilled hole wall 54 can be blocked by the circumferential protrusion 103a by casting the terminal reinforcement pipe 10a, eliminating the need for workers to climb to a high position and manually pack the opening with a rag or caulking capsule each time a hole is drilled. This allows for a highly safe and efficient caulking process.

In addition, the partition wall of the multiple circumferential protrusions 103a spaced apart in the axial direction of the terminal reinforcement tube 10a can more reliably close the gap between the outer surface of the terminal reinforcement tube 10a and the drilled hole wall 54. By providing multiple circumferential protrusions 103a spaced apart in the axial direction, if the consolidation material gets between the circumferential protrusions 103a, it is injected into the gap and the mouth caulking is performed reliably. In addition, if there is only one circumferential protrusion 103a, a larger amount of the consolidation material 41 can be injected into the inside of the packer 33 to perform the mouth caulking reliably.

In addition, by lowering the centralizer, moving it backwards, and then raising it, supporting a position behind the circumferential protrusion 103a of the terminal reinforcement tube 10a with the centralizer, and resuming the casting work of the terminal reinforcement tube 10a, it is possible to prevent interference between the circumferential protrusion 103a of the terminal reinforcement tube 10a and the centralizer, and damage to the circumferential protrusion 103a or the centralizer due to interference. It is also possible to ensure centering by the centralizer of the terminal reinforcement tube 10a.

[Scope of the invention disclosed herein]
The invention disclosed in this specification includes, in addition to each invention, embodiment, and example listed as the invention, those specified by changing partial contents of these to other contents disclosed in this specification, those specified by adding other contents disclosed in this specification to these contents, or those specified by deleting partial contents of these to the extent that partial action and effect can be obtained, and specifying them as a higher conceptualization. The invention disclosed in this specification also includes the following contents and further modified examples described below.

For example, the configuration of the terminal reinforcement pipe used in the ground reinforcement method of the present invention is not limited to the terminal reinforcement pipe 10a of the above embodiment, but may be any appropriate configuration within the scope of the present invention, and for example, the terminal reinforcement pipe 10b shown in Figures 5 and 6 may be used. The terminal reinforcement pipe 10b has a structure that is pushed in and connected, similar to the reinforcement pipe 10 and the terminal reinforcement pipe 10a, and has a discharge hole 102b for the consolidation material formed in the peripheral wall 101b, and a circumferential protrusion 103b that can close the gap between the outer periphery of the peripheral wall 101b and the drilled hole wall 54 of the drilled hole 53 is provided at the rear.

The circumferential protrusion 103b of the terminal reinforcing tube 10b is tapered so that its diameter gradually increases toward the rear end, and in the illustrated example, it is a tapered rubber tubular material whose outer circumferential surface gradually increases in diameter toward the rear end. A flange-like annular plate 104b is formed on the peripheral wall 101b near the rear end of the terminal reinforcing tube 10b and is fixed to the peripheral wall 101b by welding or the like. The circumferential protrusion 103b, which is made of a tapered rubber tubular material in this example, is fitted to the outside of the peripheral wall 101b so as to abut against the tip surface of the annular plate 104b, which regulates the position of the rear end surface.

The tip of the tapered circumferential protrusion 103b on the end reinforcing pipe 10b at the back of the hole is preferably located about 80 cm from the rear end of the end reinforcing pipe 10b, and the tip of the tapered circumferential protrusion 103b is preferably located about 50 cm from the annular plate 104b. In addition, the end reinforcing pipe 10b is completed casting in a state where it protrudes about 15 to 30 cm outward from the sprayed concrete 52, and since the rear end surface of the circumferential protrusion 103b and the annular plate 104b are located outside the sprayed concrete 52 when casting is completed, it is preferable to position the rear end surface of the tapered circumferential protrusion 103b at a position about 2 to 20 cm from the rear end of the end reinforcing pipe 10b.

In the installation work of the terminal reinforcement pipe 10b, similarly to the terminal reinforcement pipe 10a described above, when the circumferential protrusion 103b of the terminal reinforcement pipe 10b reaches close to the centralizer, the terminal reinforcement pipe 10b is installed halfway, the centralizer supporting the terminal reinforcement pipe 10b is lowered, the centralizer is moved to the rear of the circumferential protrusion 103b and the annular plate 104b so as not to interfere with them, and then raised, and the centralizer supports the position of the terminal reinforcement pipe 10b behind the circumferential protrusion 103b and the annular plate 104b, and the installation work of the terminal reinforcement pipe 10b is resumed.

After resuming the installation of the terminal reinforcing pipe 10b, the tapered surface of the circumferential protrusion 103b of the terminal reinforcing pipe 10b is pressed against the drilled wall 54 to close the gap between the outer circumferential surface of the peripheral wall 101b and the drilled wall 54, and the terminal reinforcing pipe 10b is installed to the specified position, thereby completing the installation of the terminal reinforcing pipe 10b that constitutes the end of the long reinforcing pipe 20.

The above-mentioned consolidation material injection tool 30 is attached to the cast terminal reinforcement pipe 10b, and the packer 33 is placed inside the terminal reinforcement pipe 10b at a position on the inner side of the hole from the circumferential protrusion 103b, preferably spaced apart from the inner tip of the circumferential protrusion 103b in the axial direction of the terminal reinforcement pipe 10b. In this state, the consolidation material 41 is injected inside the packer 33, and the consolidation material 41 is allowed to seep out from the packer 33 to the mouth side of the drilled hole 53, forming the mouth caulking area 42.

The peripheral wall 101b of the terminal reinforcement pipe 10b between the packer 33 arranged inside the terminal reinforcement pipe 10b and the tip of the tapered circumferential protrusion 103b on the inner side of the hole has a consolidation material discharge hole 102b formed therein. When the consolidation material 41 is injected into the inside of the packer 33, the packer 33 expands with the filling of the consolidation material 41, and the consolidation material 41 seeps out of the packer 33 and is injected into the inside of the terminal reinforcement pipe 10b on the mouth side of the drilled hole 53. At the same time, the consolidation material 41 is discharged from the discharge hole 102b of the peripheral wall 101b between the packer 33 and the tip of the circumferential protrusion 103b on the inner side of the hole, and is injected into the drilled hole 53 and the ground 51 to form the mouth caulking area 42.

After the mouth caulking area 42 is formed, similar to the case of using the terminal reinforcing pipe 10a, the consolidation material 43 is sequentially injected from the required number of rear injection hoses 34 inserted inside the long reinforcing pipe 20, and the consolidation area 44 is formed in a state where leakage of the consolidation material 43 is prevented in the mouth caulking area 42.

The ground reinforcement method using the terminal reinforcement pipe 10b has a configuration corresponding to that of the ground reinforcement method using the terminal reinforcement pipe 10a, and the tapered circumferential protrusion 103b can be smoothly inserted into the drilled hole 53 to reliably close the gap between the outer circumferential surface of the terminal reinforcement pipe 10b and the drilled hole wall 54.

This invention can be used when driving long steel pipes into the ground in front of a tunnel face during excavation, and injecting cement from the long steel pipes into the surrounding ground to reinforce the ground in front.

LIST OF SYMBOLS 10...Reinforcement pipe 11...Guide cell 12...Drilling machine 13...Fixed centralizer 14...Moveable centralizer 10a...Terminal reinforcement pipe 101a...Circumferential wall 102a...Discharge hole 103a...Circumferential protrusion 10b...Terminal reinforcement pipe 101b...Circumferential wall 102b...Discharge hole 103b...Circumferential protrusion 104b...Annular plate 20...Long reinforcement pipe 30...Injection tool 31...Terminal cap 311...Base plate 32...Injection hose for packer 33...Packer 34...Rear injection hose 41...Consolidation material 42...Mouth caulking area 43...Consolidation material 44...Consolidation area 51...Natural ground 52...Sprayed concrete 53...Drilling 54...Drilling wall 201...Natural ground 202...Long steel pipe 203...Consolidation area 204: Long-length pre-support structure 205: Long-length steel pipe 206: Long-length mirror reinforcement structure 207: Drill jumbo 208: Drilling arm 209: Guide cell 210: Drilling machine 211: Drilling rod 220, 220a, 220b: Steel pipe T: Tunnel space

Claims (3)

A ground reinforcement method in which reinforcing pipes are connected in series to the ground in front of the tunnel face during excavation, and long reinforcing pipes are cast, and a consolidated material is injected into the ground around the long reinforcing pipes to reinforce the ground in front,
A first step of installing a terminal reinforcing pipe at the end of the long reinforcing pipe, the terminal reinforcing pipe having a circumferential protrusion at its rear that can close a gap between an outer circumferential surface and a wall of a drilled hole;
A second step of disposing a packer inside the end reinforcing tube at a position deeper into the hole than the circumferential protrusion;
A third step of injecting a binder into the packer and causing the binder to seep out from the packer to the mouth side of the drilled hole to form a mouth caulking area;
A fourth step of injecting a consolidation material into the hole from the packer ,
a ground reinforcement method characterized in that, in the first step, with the terminal reinforcement pipe having been cast halfway, a centralizer that is provided in a guide cell and supports the terminal reinforcement pipe is lowered, the centralizer is moved to the rear of the circumferential protrusion so as not to interfere with the circumferential protrusion and then raised, the centralizer supports a position of the terminal reinforcement pipe rearward of the circumferential protrusion, and the casting work of the terminal reinforcement pipe is resumed . A ground reinforcement method in which reinforcing pipes are connected in series to the ground in front of the tunnel face during excavation, and long reinforcing pipes are cast, and a consolidated material is injected into the ground around the long reinforcing pipes to reinforce the ground in front,
A first step of installing a terminal reinforcing pipe at the end of the long reinforcing pipe, the terminal reinforcing pipe having a circumferential protrusion at its rear that can close a gap between an outer circumferential surface and a wall of a drilled hole;
A second step of disposing a packer inside the end reinforcing tube at a position deeper into the hole than the circumferential protrusion;
A third step of injecting a binder into the packer and causing the binder to seep out from the packer to the mouth side of the drilled hole to form a mouth caulking area;
A fourth step of injecting a consolidation material into the hole from the packer,
A ground reinforcement method, characterized in that the terminal reinforcement pipe has a plurality of circumferential protrusions provided at intervals in the axial direction . A ground reinforcement method in which reinforcing pipes are connected in series to the ground in front of the tunnel face during excavation, and long reinforcing pipes are cast, and a consolidated material is injected into the ground around the long reinforcing pipes to reinforce the ground in front,
A first step of installing a terminal reinforcing pipe at the end of the long reinforcing pipe, the terminal reinforcing pipe having a circumferential protrusion at its rear that can close a gap between an outer circumferential surface and a wall of a drilled hole;
A second step of disposing a packer inside the end reinforcing tube at a position deeper into the hole than the circumferential protrusion;
A third step of injecting a binder into the packer and causing the binder to seep out from the packer to the mouth side of the drilled hole to form a mouth caulking area;
A fourth step of injecting a consolidation material into the hole from the packer,
A ground reinforcement method, characterized in that the circumferential projection of the terminal reinforcement pipe is formed in a tapered shape that gradually increases in diameter toward the rear end .

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