JP7820195B2 - Ground reinforcement pipe and ground reinforcement method - Google Patents

Description

The present invention relates to a ground reinforcement pipe that is driven into the ground around a tunnel to reinforce the ground, and a method for reinforcing the ground using such a ground reinforcement pipe. In particular, the present invention relates to a ground reinforcement pipe and ground reinforcement method that are used as an auxiliary construction method for tunnel construction using the NATM (New Austrian Tunneling Method) method.

In the AGF (All Ground Fasten) method, which is one of the auxiliary construction methods for tunnel construction, approximately four steel pipes, each several meters long, are driven into the ground in front of the tunnel face using a jumbo drill, while being successively connected in a row, to reinforce the ground in advance.
When adding more steel pipe, the next steel pipe to be cast is placed in the guide cell of the drill jumbo, and the drill jumbo is operated so that it is aligned with the steel pipe that has already been cast.Then, the tip of the subsequent steel pipe is connected to the tail end of the steel pipe that was cast just before using a screw joint or the like.

Japanese Patent Application Laid-Open No. 2020-066908 Japanese Patent Application Laid-Open No. 2021-156117

The steel pipe extension work in this type of tunnel auxiliary construction method is complicated and time-consuming, and requires a certain level of skill.
In view of the above circumstances, the present invention aims to provide a ground reinforcement pipe and a ground reinforcement method that can simplify the work of driving the pipe into the ground in an auxiliary construction method for reinforcing the ground around a tunnel using a ground reinforcement pipe consisting of a row of multiple steel pipes (tube bodies).

In order to solve the above-mentioned problems, the present invention provides a ground reinforcement pipe that is composed of a plurality of pipe bodies arranged in a row in the pipe axis direction and is driven into the ground around a tunnel,
The diameter of the plurality of tube bodies is larger the closer to one end in the tube axis direction, and the larger diameter tube body of two adjacent tube bodies is fitted onto the outer periphery of the smaller diameter tube body so as to be slidable in the tube axis direction.

Preferably, the ground reinforcement pipe has a first locking portion at the end of the smaller diameter pipe body on one side, and a second locking portion at the end of the larger diameter pipe body on the other side in the pipe axial direction that locks with the first locking portion to prevent the two pipe bodies from coming loose.

The method of the present invention is a method for reinforcing the ground around a tunnel using the ground reinforcing pipe,
The plurality of pipe bodies constituting the ground reinforcement pipe are placed in a contracted state in which they are overlapped with each other in the pipe diameter direction and are loaded into a guide cell of a drill jumbo;
Thereafter, the plurality of pipe bodies are shifted relative to one another in the pipe axis direction by the drill jumbo, and the ground reinforcement pipe is driven into the ground while being stretched.

The present invention enables the simple and efficient driving of ground reinforcement pipes, consisting of a row of multiple steel pipes (tubular bodies), into the ground in a tunnel auxiliary construction method.

FIG. 1 is a cross-sectional view of a tunnel under construction, showing a forepiling steel pipe (ground reinforcement pipe) according to a first embodiment of the present invention, in a state where it has already been driven into the ground ahead of the tunnel face. 2(a) to 2(d) are cross-sectional views sequentially showing the process of extending the pre-receiving steel pipe. Fig. 3(a) is an enlarged cross-sectional view of the circle III in Fig. 2, showing an example of a retaining structure for the adjacent pipe body of the pre-receiving steel pipe. Fig. 3(b) is an enlarged cross-sectional view showing a modified example of the retaining structure. 4(a) to 4(c) are cross-sectional views of a tunnel under construction, sequentially showing the process of driving the forepipe steel pipe. 5(a) to 5(c) are cross-sectional views of a tunnel under construction, sequentially showing the process of driving the forepipe steel pipe. 6(a) and 6(b) are cross-sectional views of a tunnel under construction, sequentially showing the process of driving the forepipe steel pipe. 7(a) to 7(d) are cross-sectional views sequentially showing the extension process of a pre-receiving steel pipe (natural ground reinforcement pipe) according to the second embodiment of the present invention. Figure 8 shows a third embodiment of the present invention, in which Figure 8(a) is a cross-sectional view of the state before adjacent pipes of a pre-receiving steel pipe are retained, and Figure 8(b) is a cross-sectional view of the state after the adjacent pipes have been retained.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
Figure 1 shows a tunnel 1 under construction using the NATM method. The natural ground 2 is excavated and the tunnel 1 is constructed. During the tunnel construction, a forepiling steel pipe 10 (natural ground reinforcing pipe) is driven into the natural ground in front of the tunnel face 1e (around the tunnel) using the AGF method, which is one of the auxiliary construction methods.

As shown in Figure 1, the noose-receiving steel pipe 10 is composed of four (multiple) pipe bodies 11. These pipe bodies 11 are connected in a row in the pipe axial direction. To distinguish between the four (multiple) pipe bodies 11, they are designated by the letters A, B, C, and D, respectively, from the tip end (one end, right side in Figure 1) to the tail end (the other end, left side in Figure 1) in the pipe axial direction. These pipe bodies 11 have different pipe diameters, with the pipe body 11 located closer to the tip end (one end) in the pipe axial direction having a larger diameter. In other words, the pipe diameters increase in the order of pipe body 11D, pipe body 11C, pipe body 11B, and pipe body 11A.

As shown in Figures 2(a) to 2(d), between two adjacent pipes 11A and 11B, the larger-diameter pipe 11A is fitted onto the outer periphery of the smaller-diameter pipe 11B so that it can slide in the pipe axial direction. The same is true for pipes 11B and 11C, and for pipes 11C and 11D. This creates a nested structure between pipes 11A to 11D, allowing the forward-receiving steel pipe 10 to expand and contract.

As shown in Figure 1, the forepipe steel pipe 10 driven into the ground 2 is elongated. The length of the elongated forepipe steel pipe 10 is, for example, approximately 12 meters, but the present invention is not limited to this.

As shown in Figure 3(a), of the two adjacent pipes 11A, 11B, the smaller diameter pipe 11B has a first locking portion 21 at its tip end (the end on one side in the pipe axial direction). The larger diameter pipe 11A has a second locking portion 22 at its tail end (the end on the other side in the pipe axial direction). When the long, tip-supported steel pipe 10 is extended, the first locking portion 21 and the second locking portion 22 butt against each other and lock into each other. This prevents the pipes 11A, 11B from coming loose.
Although not shown in the drawings, the same applies to the retaining structures between the tubes 11B and 11C and between the tubes 11C and 11D.

As shown in Figure 3(a), for example, the first locking portion 21 is formed by a stepped annular protrusion 21a that protrudes radially outward from the outer peripheral surface of the tip end of the small-diameter tube 11B. The second locking portion 22 is formed by a stepped annular protrusion 22a that protrudes radially inward from the inner peripheral surface of the tail end of the large-diameter tube 11A.

As shown in Figure 3(b), the first locking portion 21 may be formed by an outer peripheral tapered portion 21b provided on the outer periphery of the tip end of the small-diameter tube 11B. The second locking portion 22 may be formed by an inner peripheral tapered portion 22b provided on the inner periphery of the tail end of the large-diameter tube 11A. The outer peripheral tapered portion 21b tapers in diameter toward the tip end surface 12 of the tube 11B. The inner peripheral tapered portion 22b tapers in diameter toward the tail end surface 13 of the tube 11A.

The material of the tube body 11 may be ordinary steel or high-tensile steel. If the tube body 11 is made of high-tensile steel, the required strength can be ensured even if the tube body 11 is thin, and the weight can be reduced.
Since there is no need to form a screw at the end of each tube 11 for connecting with an adjacent tube, the thickness can be made smaller and the weight can be made even lighter.

The fore-receiving steel pipe 10 is installed as follows.
As shown in Figures 2(a) and 4(a), the nodding steel pipe 10 is put into a contracted state by overlapping four (multiple) pipe bodies 11 in the pipe diameter direction. The nodding steel pipe 10 in the contracted state is loaded into the guide cell 41 of the drill jumbo 40. A drilling rod 51 is inserted into the inside of the nodding steel pipe 10. A drilling bit 50 is attached to the tip of the leading pipe body 11A via a bit adapter 52. The tip of the drilling rod 51 is connected to the bit adapter 52. The tail end of the drilling rod 51 is connected to the drifter 42.

As shown in Figure 2(a), a locking plate 15 is joined to the tail end of the rearmost tube body 11D by joining means. Joining means include screw connection, fitting, welding, etc.

Thereafter, as shown in FIGS. 4 to 6, the forepound steel pipe 10 is driven into the natural ground 2 while being stretched by using a drill jumbo 40 so as to shift the pipe bodies 11D to 11A relative to one another in the pipe axis direction.
In detail, as shown in Figures 4(a) to 4(b), by advancing the drifter 42 along the guide cell 41, the drilling bit 50 excavates the ground 2 in front of the working face 1e while driving the foreplume pipe 10 into the ground 2.

At this time, the leading pipe 11A is advanced together with the drilling bit 50. The remaining pipes 11B, 11C, and 11D are advanced together with the leading pipe 11A through direct or indirect friction, engagement, or other means with the leading pipe 11A. Pipes 11B to 11D may be advanced by being pushed by the locking plate 15. Therefore, as shown in Figure 4(b), the four (multiple) pipes 11 of the contracted leading pipe 10 are advanced together with the drilling bit 50. As a result, the leading pipe 10 is driven into the natural ground 2 while remaining in its contracted state.

Next, as shown in FIG. 4( c ), the drifter 42 is detached from the drilling rod 51 and is moved backward along the guide cell 41 .
Next, as shown by the two-dot chain line in Figure 4(c), the drilling rod 51 is extended by a rod changer (not shown). At this time, there is no need to extend the pipe body.

Next, as shown in Figures 4(c) to 5(a), the drifter 42 is again advanced along the guide cell 41, and the drilling bit 50 excavates the natural ground 2 in front of the working face 1e while driving the fore-receiving steel pipe 10. At this time, as shown in Figures 2(a) to 2(b), the leading pipe 11A is advanced together with the drilling bit 50. The intermediate pipes 11B and 11C engage with the leading pipe 11A and advance together with it. The rearmost pipe 11D abuts against the centralizer 43 via the locking plate 15 and is prevented from advancing. As a result, pipes 11A to 11C shift toward the tip in the pipe axial direction relative to pipe 11D, and the fore-receiving steel pipe 10 is extended by the length of one pipe 11.

Next, as shown in Figure 5(b), the drifter 42 is retracted and the drilling rod 51 is extended. In this case, there is no need to extend the tube.

Next, as shown in Figures 5(b) and 5(c), the drifter 42 is again advanced to continue driving the fore-end pipe 10. At this time, as shown in Figures 2(b) and 2(c), the leading pipe 11A is advanced together with the drill bit 50. The second-from-the-front pipe 11B is advanced together with the leading pipe 11A by engaging with it. The third-from-the-front pipe 11C is prevented from advancing when its second locking portion 22 abuts against the first locking portion 21 of the trailing pipe 11D (see Figure 3), and the engagement between the third pipe 11C and the leading pipe 11A is released. As a result, pipes 11A and 11B shift toward the tip in the axial direction relative to pipe 11C, further extending the fore-end pipe 10.

Next, as shown in Figure 6(a), the drifter 42 is retracted again and the drilling rod 51 is extended. In this case, there is no need to extend the tube.

Next, as shown in Figures 6(a) and 6(b), the driving of the fore-receiving steel pipe 10 is continued by again advancing the drifter 42. As shown in Figures 2(c) and 2(d), the leading pipe 11A is advanced together with the drilling bit 50. The second-leading pipe 11B is prevented from advancing when its second locking portion 22 abuts against the first locking portion 21 of the third-leading pipe 11C (see Figure 3), and the engagement between the second pipe 11B and the leading pipe 11A is released. This shifts pipe 11A toward the tip in the pipe axial direction relative to pipes 11B, further extending the fore-receiving steel pipe 10.

Eventually, as shown in Figure 3, the second locking portion 22 of the leading pipe 11A abuts against the first locking portion 21 of the second-leading pipe 11B. This causes the leading steel pipe 10 to reach its maximum extension, as shown in Figures 2(d) and 6(b), and the driving of the leading steel pipe 10 is completed.

Thereafter, as shown in FIG. 1 , the drilling rod 51 is pulled out from the fore-receiving steel pipe 10 , and the drill jumbo 40 is separated from the fore-receiving steel pipe 10 .
In this way, the telescopic forepipe steel pipe 10 can eliminate the need for pipe extension work during driving work, thereby enabling driving work to be carried out simply and efficiently.

Next, another embodiment of the present invention will be described. In the following embodiment, the same components as those already described will be denoted by the same reference numerals in the drawings and the description thereof will be omitted.
Second Embodiment (FIG. 7)
As shown in FIG. 7, when the fore-receiving steel pipe 10 is driven, the pipe bodies 11 may be advanced in sequence starting from the one on the tip side, so that the fore-receiving steel pipe 10 is extended.
More specifically, as shown in Figures 7(a) and 7(b), at the beginning of driving, only the leading pipe 11A is advanced together with the drill bit 50, and the other pipes 11B to 11D remain in their original positions.

Eventually, as shown in Figure 7(b), the second locking portion 22 of the leading tube 11A abuts against the first locking portion 21 of the second-from-leading tube 11B (see Figure 3). Thereafter, as shown in Figures 7(b) and 7(c), the second tube 11B is advanced together with the leading tube 11A.

Next, as shown in Figure 7(c), the second locking portion 22 of pipe 11B abuts against the first locking portion 21 of the third pipe 11C from the front (see Figure 3). Thereafter, as shown in Figures 7(c) to 7(d), the third pipe 11C is advanced together with the front pipe 11A and the second pipe 11B. This causes the leading steel pipe 10 to enter an elongated state, as shown in Figure 7(d).

Third Embodiment (FIG. 8)
As shown in FIG. 8, the third embodiment of the present invention relates to a modified structure for preventing adjacent pipes from coming off each other.
8(a), of the adjacent tubes 11A and 11B, the larger-diameter tube 11A has a second locking portion 22 formed at the tail end thereof. The second locking portion 22 includes an annular locking recess 23 and a tapered guide portion 24.

Specifically, the tail end of the larger-diameter tube 11A is raised radially inward along its entire circumference. An annular locking recess 23 is formed on the inner surface of this raised portion 22e. The raised portion 22e closer to the tail end surface 13 than the annular locking recess 23 nearly contacts the outer surface of the smaller-diameter tube 11B. The raised portion 22e on the opposite side of the annular locking recess 23 from the tail end surface 13 (the right side in Figure 8(a)) gradually decreases in height as it moves away from the annular locking recess 23 in the axial direction, thereby forming a tapered guide portion 24. The inner surface of the tapered guide portion 24 forms a tapered surface 24a that expands in diameter toward the center of the tube 11A in the axial direction. The tapered surface 24a is connected to the straight, cylindrical inner surface 14 of the tube 11A at an obtuse angle.

Of the adjacent tubes 11A and 11B, the tube 11B with the smaller diameter has a first locking portion 21 with an annular protrusion 21a formed at its tip. The annular protrusion 21a is in substantial contact with the inner circumferential surface 14 of the tube 11A.

As shown in Figure 8(a), before and during the driving of the fore-receiving steel pipe 10 (ground reinforcement pipe), the pipes 11A and 11B can slide relative to each other in the pipe axial direction. As they slide relative to each other, the annular protrusion 21a of the small-diameter pipe 11B slides on the inner surface 14 of the large-diameter pipe 11A. At the same time, the raised portion 22e on the tail end surface 13 of the large-diameter pipe 11A slides on the outer surface of the small-diameter pipe 11B.

When the larger-diameter tube 11A slides toward the tip of the smaller-diameter tube 11B in the axial direction (in the direction of the white arrow in Figure 8(a)) due to the impact, the annular protrusion 21a eventually rides up onto the tapered surface 24a of the tapered guide portion 24. This causes the tail end of tube 11A and the tip end of tube 11B to elastically deform in the radial direction.

As the driving continues, as shown in Figure 8(b), the annular protrusion 21a moves over the tapered guide portion 24 and fits into the annular locking recess 23. At the same time, the tail end of the tube 11A and the tip end of the tube 11B elastically return to their original position. This irrevocably locks the first locking portion 21 and the second locking portion 22 together. Therefore, not only are the adjacent tubes 11A and 11B prevented from slipping out of each other, but relative sliding is also restricted.

Although not shown, the third embodiment also has a similar connection structure to that shown in Figure 8 between pipes 11B and 11C, and between pipes 11C and 11D. As a result, according to the third embodiment, it is possible to prevent the forward-receiving steel pipe 10 from shrinking after it has been driven to its maximum length.

The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the invention.
For example, the present invention is not limited to the AGF method, but can also be applied to a head bolt method. The ground reinforcement pipe is not limited to the fore-receiving steel pipe of the AGF method, but may be a head bolt.

The present invention can be applied to auxiliary construction methods such as the AGF method and head bolt method for reinforcing the ground around a tunnel during tunnel construction.
can be applied to.

1 Tunnel 2 Ground 1e Face 10 Fore-support steel pipe (ground reinforcement pipe)
11, 11A to 11D Tube body 12 Tip surface 13 Tail end surface 14 Inner peripheral surface 15 Locking plate 21 First locking portion 21a Annular convex portion 21b Outer peripheral tapered portion 22 Second locking portion 22a Annular convex portion 22b Inner peripheral tapered portion 22e Raised portion 23 Annular locking recess 24 Tapered guide portion 24a Tapered surface 40 Drill jumbo 41 Guide cell 42 Drifter 43 Centralizer 50 Drilling bit 51 Drilling rod 52 Bit adapter

Claims (2)

A ground reinforcement pipe consisting of a plurality of pipe bodies arranged in a row in the pipe axis direction and driven into the ground around a tunnel,
The diameter of each of the plurality of pipe bodies is larger as the pipe body is arranged closer to one end in the pipe axis direction, and the pipe body with a larger diameter is fitted onto the outer periphery of the pipe body with a smaller diameter of two adjacent pipe bodies so as to be slidable in the pipe axis direction ,
a first locking portion is provided at an end portion of the small-diameter tube on the one end side, and a second locking portion is provided at an end portion of the large-diameter tube on the other end side in the tube axis direction, the second locking portion being engaged with the first locking portion to prevent the two tubes from coming off each other,
One of the first locking portion and the second locking portion has an annular protrusion,
the other of the first and second locking portions has an annular locking recess and a tapered guide portion whose protruding height gradually decreases as it becomes farther from the annular locking recess,
A ground-reinforced pipe characterized in that, when the two pipe bodies are slid relatively in the pipe axis direction so that the end portion on the one end side and the end portion on the other end side approach each other in the pipe axis direction, the annular convex portion rides up onto the tapered guide portion, causing the pipe body to elastically deform in the pipe diameter direction, and further, the annular convex portion rides over the tapered guide portion and fits into the annular locking recess, causing the pipe body to elastically return to its original state . A method for reinforcing the ground around a tunnel using the ground reinforcing pipe according to claim 1,
The plurality of pipe bodies constituting the ground reinforcement pipe are placed in a contracted state in which they are overlapped with each other in the pipe diameter direction and are loaded into a guide cell of a drill jumbo;
Then, the drill jumbo is used to shift the multiple pipe bodies relative to each other in the pipe axis direction , causing the pipe bodies to undergo elastic deformation due to the climbing up, and the climbing over causes the annular convex portion to fit into the annular locking concave portion and the elastic recovery , and the ground reinforcement pipe is then driven into the ground while being stretched.