Construction method of ground reinforcement pipe

Abstract

To prevent difficulty in fitting due to sediment in a concave part of a female fitting part when fitting male and female fitting parts of a leading pipe and a trailing pipe of a natural ground reinforcement pipe driven into the natural ground around a tunnel, and to easily check whether the fitting state is good or bad.SOLUTION: A leading pipe 11 and a trailing pipe 12 of a natural ground reinforcement pipe 9 are spliced in a straight line. A male fitting part 32 having a convex or uneven outer peripheral surface is provided at a rear end part of the leading pipe 11. A female fitting part 42 for receiving the male fitting part 32 is provided at the distal end part of the trailing pipe 12. The female fitting part 42 includes a plurality of fitting claws 43 arranged in an annular shape with concave or uneven inner peripheral surfaces. Adjacent fitting claws 43 are separated by slits 44. Each fitting claw 43 is fitted with the male fitting part 32.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a reinforcing pipe that is driven into the ground around a tunnel as an auxiliary construction method, for example, in the NATM (New Austrian Tunneling Method) construction method, to reinforce the ground, and in particular to a reinforcing pipe that is made longer by sequentially joining multiple pipes in a straight line. [Background technology]

[0002] In the AGF (All Ground Fasten) method, which is one of the auxiliary tunnel construction methods, about four steel pipes, each about 3 m in length, are driven into the ground in front of the tunnel face, one after the other, to form a long, fore-reinforced steel pipe (ground reinforcement pipe) about 12 m in length (see Patent Document 1, etc.).

[0003] In the long, top-receiving steel pipe disclosed in Patent Document 1, of the two pipes to be joined, for example, the end of the leading pipe serves as a female mating portion with a recess on its inner circumferential surface, and the end of the trailing pipe serves as a male mating portion with a protrusion on its outer circumferential surface. Furthermore, three slits are formed in the male mating portion at 120-degree intervals. This separates the male mating portion into three mating claws. The male mating portion is inserted into the female mating portion. At this time, the three mating claws are tilted inward, reducing the diameter of the male mating portion. When inserted to the locking position, the mating claws elastically return, and the male and female mating portions are locked together. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-111880 Summary of the Invention [Problem to be solved by the invention]

[0005] When the inventors installed the long-length, no-tip-supporting steel pipe (ground-reinforced pipe) described in Patent Document 1, they discovered that when the leading pipe was driven into the ground, soil that had gotten inside the leading pipe accumulated in the recess of the female mating section. When the male mating section of the trailing pipe was then fitted into the female mating section, the soil in the recess became an obstacle, making it difficult to fit the female mating section and the male mating section together. Furthermore, because the fitting is performed inside the completely annular female mating section, it is impossible to confirm whether the male mating section has been fitted to the desired position or whether it has been fitted properly. It is also impossible to confirm whether the mating claws have been deformed or broken. If the mating claws are deformed or broken, they may get caught when the drilling bit at the tip of the long no-tip-supporting steel pipe is pulled out after driving. In view of the above circumstances, the present invention aims to prevent soil and sand from making it difficult to fit the male and female fitting portions of a leading pipe body and a trailing pipe body together when they are fitted together during the construction of long pre-receiving steel pipes (ground reinforced pipes), and to make it easy to check whether the fitting is good or bad. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems, the ground reinforcement pipe according to the present invention is a ground reinforcement pipe that is driven into the ground around a tunnel, a leading pipe; and a following pipe arranged closer to the tunnel than the leading pipe and joined in a straight line to the leading pipe; the leading pipe has a leading pipe main body and a male fitting portion provided at a rear end portion of the leading pipe main body, the following pipe has a following pipe main body and a female fitting portion provided at a tip end of the following pipe main body and adapted to receive the male fitting portion; The outer peripheral surface of the male fitting portion is convex or concave-convex, The female fitting portion has a concave or convex inner circumferential surface and includes a plurality of fitting claws arranged in an annular shape, and adjacent fitting claws are separated by slits, Each mating claw is adapted to be mated with the male mating portion.

[0007] With this ground-reinforced pipe, even if soil gets inside the leading pipe driven into the ground first during construction, and even if the soil adheres to the inner circumferential surface of the male fitting portion at the rear end of the leading pipe, it does not affect the fitting of the male and female fitting portions. It is almost impossible for soil to get inside the unconnected trailing pipe. Therefore, soil almost never accumulates in the recess of the female fitting portion at the tip of the trailing pipe. This allows for a good fit between the male fitting portion of the leading pipe and the female fitting portion of the trailing pipe. Furthermore, because the female mating part that fits over the outer periphery of the male mating part has a slit, the mating state of the male and female mating parts can be visually confirmed from the outside through the slit, making it easy to check whether the male mating part has been mated to the specified mating position, whether it has been mated properly, and whether the mating claws are deformed or broken. Even if the mating claws are deformed or broken, the mating claws are positioned on the outer periphery of the male mating portion, so the drilling bit will not get caught on the deformed or broken mating claws when being pulled out, and the drilling bit can be pulled out reliably.

[0008] The number of mating claws of the female mating portion is preferably four or more, which makes it easier to elastically deform the mating claws during mating.

[0009] It is preferable that the preceding pipe body, the male fitting portion, the following pipe body, and the female fitting portion are each made of high-tensile steel having a tensile strength of 590 MPa or more. This allows the leading and trailing pipes to be made thinner and lighter in weight. In addition, the female mating portion can be given spring properties (high elasticity), and the mating claws that bend outward during the insertion operation of the male mating portion can be elastically returned (spring back) with force as soon as the insertion is complete, allowing the mating claws to fit securely into the male mating portion.

[0010] The method of the present invention is a method for constructing the natural ground reinforcement pipe, The leading pipe is driven into the natural ground with the male fitting portion facing backward, and the male fitting portion is left protruding into the tunnel, Next, in the tunnel, the female fitting portion of the following pipe is fitted forward with the male fitting portion, Thereafter, the preceding pipe and the following pipe are further driven into the natural ground. According to this method, the female mating portion before mating is positioned in the tunnel interior space, so that earth and sand that has entered the preceding pipe will not get into the recess of the female mating portion before mating. Therefore, the male and female mating portions can be mated properly. In addition, the mating state of the male and female mating portions can be checked from the outside through the slit in the female mating portion. [Effects of the Invention]

[0011] According to the present invention, the male and female fitting portions of the leading pipe and the trailing pipe of the ground reinforcement pipe can be fitted together reliably, and the quality of the fitting state can be easily confirmed. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a cross-sectional view showing how a long pre-receiving steel pipe (ground reinforcement pipe) according to a first embodiment of the present invention is driven into the ground around a tunnel. [Figure 2] FIG. 2 is an enlarged cross-sectional view of the circle II in FIG. [Figure 3] FIG. 3 is an exploded perspective view of the male and female end pipe portions of the long, top-receiving steel pipe. [Figure 4] Figure 4(a) is a cross-sectional view of a tube end portion having a male mating portion of a leading tube, and Figure 4(b) is a cross-sectional view of a tube end portion having a female mating portion of a trailing tube. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Figure 1 shows a tunnel 1 being constructed using the NATM method. The natural ground 2 is excavated and the tunnel 1 is constructed. In the construction of the tunnel 1, the AGF method, for example, is used as a supplementary method for reinforcing the natural ground. Using the AGF method, a long forepiling steel pipe 9 (natural ground reinforcement pipe) is driven into the natural ground 2 in front of the tunnel face 3 (on the right in Figure 1).

[0014] The total length of the long pre-receiving steel pipe 9 is, for example, about 12 m. The long pre-receiving steel pipe 9 includes multiple (for example, about four) steel pipe bodies 10. The length of each pipe body 10 is, for example, about 3 m. Two adjacent pipe bodies 10 are connected in a straight line. To distinguish between the two pipe bodies 10, the pipe body 10 that was driven first is referred to as the "preceding pipe body 11," and the pipe body 10 that is positioned closer to the tunnel than the preceding pipe body 11 and is joined to the preceding pipe body 11 is referred to as the "subsequent pipe body 12."

[0015] 2 and 3, the leading pipe 11 has a leading pipe main body 13 and an end pipe portion 30. The leading pipe main body 13 has a length slightly shorter than the entire length of the leading pipe 11 and is thinner than the end pipe portion 30.

[0016] As shown in Figures 2 and 4(a), an end pipe section 30 is provided at the rear end of the leading pipe body 13. The end pipe section 30 is composed of a short pipe separate from the leading pipe body 13 and is joined to the leading pipe body 13 by welding or the like. The end pipe section 30 integrally includes a cylindrical section 31 on the leading pipe body 13 side (right side in Figure 2) and a male fitting section 32 on the following pipe body 12 side (left side in Figure 2). The cylindrical section 31 has a thicker cylindrical shape than the leading pipe body 13. The opposing end faces of the cylindrical section 31 and the leading pipe body 13 are butted against each other and welded. The outer circumferential surface of the cylindrical section 31 is flush with and continuous with the outer circumferential surface of the leading pipe body 13. The inner circumferential surface of the cylindrical section 31 protrudes radially inward from the inner circumferential surface of the leading pipe body 13.

[0017] As shown in Figures 2 and 4(a), the male fitting portion 32 is provided on the rear end side (left side in Figure 2) of the cylindrical portion 31 of the end tube portion 30. The outer circumferential surface of the male fitting portion 32 is formed with a smaller diameter than the outer circumferential surface of the cylindrical portion 31, and has a convex portion 32a protruding outward and a concave portion 32b (convex or concave-convex portion) recessed from the outer circumferential side, forming a wedge-shaped or serrated cross section. The male fitting portion 32 is annular and extends around the entire circumference of the short-tube-shaped end tube portion 30. The inner peripheral surface of the male fitting portion 32 is formed into a smooth cylindrical surface, and is flush with and continuous with the inner peripheral surface of the cylindrical portion 31 . The male fitting portion 32 does not have a slit formed therein.

[0018] 2 and 4(b), the following pipe 12 has a following pipe main body 14 and an end pipe portion 40. The following pipe main body 14 has a length slightly shorter than the entire length of the following pipe 12 and is thinner than the end pipe portion 40.

[0019] An end pipe portion 40 is provided at the tip of the following pipe body 14. The end pipe portion 40 is composed of a short pipe separate from the following pipe body 14 and is joined to the following pipe body 14 by welding or the like. The end pipe portion 40 integrally includes a cylindrical portion 41 on the following pipe body 14 side (left side in FIG. 2) and a female fitting portion 42 on the leading pipe body 11 side (right side in FIG. 2). The cylindrical portion 41 has a thicker cylindrical shape than the following pipe body 14. The opposing end faces of the cylindrical portion 41 and the following pipe body 14 are butted and welded together. The outer circumferential surface of the cylindrical portion 41 is flush with and continuous with the outer circumferential surface of the following pipe body 14. The inner circumferential surface of the cylindrical portion 41 protrudes radially inward from the inner circumferential surface of the following pipe body 14.

[0020] As shown in FIGS. 2 and 4(b), a female fitting portion 42 is provided on the tube end portion 40 closer to the tip (to the right in FIG. 2) than the cylindrical portion 41. The female fitting portion 42 includes a plurality of (four in this example) fitting claws 43 arranged in a ring shape. The inner circumferential surface of the fitting claws 43, and therefore the female fitting portion 42, is formed with a larger diameter than the inner circumferential surface of the cylindrical portion 41 and has a convex portion 43a protruding toward the inner circumferential side and a concave portion 43b (a convex or concave-convex portion) recessed from the inner circumferential side. As a result, each fitting claw 43 has a wedge-shaped or serrated cross section. Slits 44 are formed between adjacent fitting claws 43 to separate them. The slits 44 extend straight along the tube axis L from a step portion 45 at the boundary between the cylindrical portion 41 and the female fitting portion 42 to reach the tip of the tube end portion 40. The outer peripheral surface of the female fitting portion 42 is formed into a smooth cylindrical surface, and is continuous with the outer peripheral surface of the cylindrical portion 41 so as to be flush with it. The number of the engaging claws 43 and the number of the slits 44 are not limited to four, and may be one to three, but is preferably four or more.

[0021] 2, the male fitting portion 32 of the leading tube 13 is received in the female fitting portion 42 of the following tube 12. Each fitting claw 43 is fitted into the male fitting portion 32. The protrusion 32a fits into the recess 43b, and the protrusion 43a fits into the recess 32b.

[0022] The pipe bodies 13, 14 and the end pipe portions 30, 40 are made of high-tensile steel with a tensile strength of 590 MPa or more, which gives each fitting claw 43 of the end pipe portion 40 springiness (high elasticity).

[0023] The outer diameter of the pipe bodies 13 and 14 is preferably about 70 mm to 120 mm, and the pipe thickness is preferably about 2.5 mm to 4 mm, more preferably about 2.5 mm to 3.5 mm, thereby reducing the weight of the pipe body 10. The trailing pipe body 12 becomes the leading pipe body 11 relative to the pipe body 10 that is connected behind it. The trailing pipe body 14 becomes the leading pipe body 13 relative to the pipe body 10 that is connected behind it.

[0024] The long pre-support steel pipe 9 is driven in as follows. As shown in Figure 1, a drill jumbo 5 is installed inside a tunnel 1. A drilling bit 15 is provided at the tip of a pipe 10 located at the very tip of a long fore-receiving steel pipe 9. The drill jumbo 5 is driven to drive the pipe 10 into the ground 2 while the drilling bit 15 excavates the ground 2.

[0025] As shown in Figures 1 and 2, the male fitting portion 32 of the leading pipe 11 faces backward. In this state, the leading pipe 11 is driven into the natural ground 2. Driving is temporarily stopped before the male fitting portion 32 at the rear end is buried in the natural ground 2. This allows the male fitting portion 32 to protrude into the tunnel 1.

[0026] Sediment from the natural ground 2 may get inside the leading pipe 11. This sediment may reach the rear end of the leading pipe 11 and adhere to the inner circumferential surface of the short-tube-shaped end pipe portion 30. However, it is difficult for the sediment to get around to the outer circumferential surface of the end pipe portion 30. This prevents sediment from accumulating in the recess 32b on the outer periphery of the male fitting portion 32. Even if sediment accumulates in the recess 32b, it is on the outer circumferential surface of the end pipe portion 30 and can be easily removed.

[0027] Inside the tunnel 1, the trailing pipe 12 is placed in the guide cell 6 of the drill jumbo 5 with the female fitting portion 42 facing forward. At this stage, the trailing pipe 12 is positioned in the tunnel 1 away from the leading pipe 11, so there is almost no chance of soil or sand getting inside the trailing pipe 12. Therefore, soil or sand rarely accumulates in the recesses 43b of the fitting claws 43 of the female fitting portion 42.

[0028] Next, the male fitting portion 32 protruding into the tunnel 1 is received by the female fitting portion 42 of the subsequent pipe 12, and the male fitting portion 32 and the fitting claws 43 of the female fitting portion 42 are fitted together. When fitting, the male fitting part 32 is free from soil and sand, and even if soil and sand are present, they can be easily removed before fitting, and the fitting claws 43 are hardly ever soiled, so that the male fitting part 32 and the fitting claws 43 can be fitted together well.

[0029] During the mating process, each mating claw 43 warps outward to climb over the protrusion 32 a of the male mating portion 32 . The mating claws 43, made of high-tensile steel with a tensile strength of 590 MPa or more, have high elasticity, so that each mating claw 43 springs back with force as soon as mating is complete. This allows the mating claws 43 to be securely mated with the male mating portion 32. In other words, poor mating due to insufficient elastic restoring force of the mating claws can be avoided. By providing four or more mating claws 43 on the female mating portion 42, the mating claws 43 can be easily elastically deformed during the mating operation.

[0030] Upon mating, the female mating portion 42 fits over the outer periphery of the male mating portion 32. A slit 44 is formed in the female mating portion 42, allowing the operator to visually check the mated state of the male and female mating portions 32, 42 from the outside through the slit 44. This makes it easy to check whether the male mating portion 32 has been mated to the specified mating position, whether it has been mated properly, and whether the mating claws 43 are deformed or broken. If poor mating is confirmed, the mating operation is repeated.

[0031] After confirming that they are properly fitted, the leading pipe 11 and the trailing pipe 12 are further driven into the natural ground 2 using a drill jumbo 5. In this way, four (plural) pipe bodies 10 are driven into the natural ground 2 while being sequentially joined together, thereby forming a long pre-supported steel pipe 9 (natural ground reinforced pipe).

[0032] Thereafter, the drilling bit 15 is pulled out through the inside of the long tip-receiving steel pipe 9. Since it has been confirmed that the male and female fitting portions 32, 42 are fitted together well, the drilling bit 15 can be pulled out smoothly. Even if the engaging claws 43 are deformed or broken, the engaging claws 43 are arranged on the outer periphery of the end tube portion 30, so the drilling bit 15 will not get caught on the deformed or broken engaging claws 43 when being pulled out. Therefore, the drilling bit 15 can be pulled out reliably.

[0033] 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 protrusions 32a of the male fitting portion 32 may be provided in two or more stages in the tube axis direction, and the protrusions 43a of the fitting claws 43 may be provided in two or more stages in the tube axis direction. [Industrial Applicability]

[0034] The present invention can be applied to, for example, long pre-supported steel pipes for use in the AGF method. [Explanation of symbols]

[0035] 1. Tunnel 2. Ground 3 Cutting edge 5. Jumbo Drill 6 Guide Cell 9 Long pre-supported steel pipe (ground reinforcement pipe) 10. Body 11 Leading pipe 12 Subsequent pipe body 13 Leading tube body 14 Subsequent pipe body 15 drilling bits 30 End tube section 31 Cylindrical part 32 Male mating part 32a Convex part 32b Recess 40 End tube section 41 Cylindrical part 42 Female mating part 43 Interlocking claw 43a Convex part 43b Recess 44 Slit 45 Step part

Claims

1. A method for constructing a ground reinforcement pipe to be driven into the ground around a tunnel, comprising: a leading pipe; and a trailing pipe that is positioned closer to the tunnel than the leading pipe and is joined in a straight line to the leading pipe, the leading pipe having a leading pipe body and a male fitting portion provided at the rear end of the leading pipe body, the trailing pipe having a trailing pipe body and a female fitting portion provided at the front end of the trailing pipe body for receiving the male fitting portion, the male fitting portion having a convex or concave-convex outer surface, the female fitting portion having a concave or concave-convex inner surface and including a plurality of fitting claws arranged in a ring, adjacent fitting claws being separated by slits, and each fitting claw being fitted with the male fitting portion, The leading pipe is driven into the natural ground with the male fitting portion facing backward, and the male fitting portion is left protruding into the tunnel, Next, in the tunnel, the female fitting portion of the following pipe is fitted forward with the male fitting portion, A method for constructing a ground-reinforced pipe, characterized in that the mating state of the female mating portion and the male mating portion is confirmed from the outside through the slit, and after confirming that they are mated well, the preceding pipe body and the following pipe body are further driven into the ground.

2. 2. The method for constructing a natural ground reinforcement pipe according to claim 1, wherein the number of fitting claws of the female fitting portion is four or more.

3. 3. A method for constructing a ground-reinforced pipe as described in claim 1 or 2, characterized in that the preceding pipe body, the male fitting portion, the following pipe body, and the female fitting portion are each made of high-tensile steel having a tensile strength of 590 MPa or more.

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