Steel pipe reinforcement members, ground reinforcement methods, and ground reinforcement structures

Abstract

To improve construction efficiency by efficiently removing steel pipe reinforcement members and sorting members at the time of disposal.SOLUTION: A steel pipe reinforcement member that is driven into the ground G to reinforce it in order to prevent the ground G from collapsing during tunnel excavation comprises a steel pipe 2 driven into the ground G, a drill bit 3 for ground excavation provided rotatably in a state separated from the steel pipe 2 at the tip of the steel pipe 2, and blade portions 21 provided at a plurality of locations on an outer peripheral surface of the steel pipe 2 in the pipe axis direction X of the steel pipe 2 and inclined with respect to the pipe axis O. The blade portion 21 having the largest diameter among the plurality of blade portions 21 provides a steel pipe reinforcement member having a configuration larger than the outer diameter of the drill bit 3.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a steel pipe reinforcing member, a ground reinforcing method, and a ground reinforcing structure. [Background technology]

[0002] Conventionally, when excavating a tunnel in soft ground, the AGF method (All Ground Fasten, a long steel pipe forepiling method) or the mirror reinforcement method has been used to prevent collapse (see, for example, Patent Document 1). For example, in a specific example of mirror reinforcement, steel pipes are driven into the mirror surface during tunnel excavation, and mortar is injected to anchor them to the ground. This prevents the ground from collapsing and allows time for construction of the tunnel section up to the mirror surface. After the mirror surface has been reinforced with steel pipes and mortar, the reinforced ground ahead of the mirror surface is excavated, along with the reinforcing member with the steel pipes and mortar anchored in place, and the tunnel is extended. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-022501 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned mirror reinforcement method and the like, construction in which a reinforcing member is driven into the ground to reinforce it, and then the reinforcing member is excavated together with the ground has the following problems. In other words, due to the recent tightening of environmental regulations, it is necessary to separate the reinforcing members from the excavated soil, and then separate the steel pipes and mortar of the reinforcing members before disposing of them as waste. On the other hand, to maximize the effectiveness of reinforcing members that use steel pipes and mortar, it is necessary to improve the adhesion between the two, and measures such as applying shear-stopping treatment to the steel pipes are often taken. However, this makes it difficult to separate the steel pipes and mortar when disposing of the reinforcing members, which requires a great deal of effort and cost, and there is room for improvement in this regard.

[0005] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a steel pipe reinforcing member, a ground reinforcement method, and a ground reinforcement structure that enable the steel pipe reinforcing member to be removed and the components to be separated efficiently when disposed of, thereby improving construction efficiency. [Means for solving the problem]

[0006] In order to achieve the above object, the steel pipe reinforcing member according to the present invention is a steel pipe reinforcing member that is driven into the ground to reinforce it and prevent the ground from collapsing during excavation, and includes a steel pipe to be driven into the ground, a drill bit for excavating the ground that is rotatably provided at the tip of the steel pipe while being separated from the steel pipe, and a drill bit for drilling the ground that is attached to the outer surface of the steel pipe. In The axial direction of the steel pipe spaced apart Located in multiple locations and a blade group including a plurality of blades each having a plate-like blade portion inclined with respect to the pipe axis, the blade portion being attached such that the inclination angle of the plate surface with respect to the pipe axis is greater than 0° and less than 45°, the height in the radial direction is set to be greater than the plate thickness, the diameter of the steel pipe is smaller than the diameter of the drill bit, and the plurality of blades The blade portion having the largest diameter is characterized by being larger than the outer diameter of the drill bit.

[0007] In addition, the ground reinforcement method of the present invention is a ground reinforcement method using the above-mentioned steel pipe reinforcing member, and is characterized in that the steel pipe provided with the blade portion is driven into the ground while rotating the drill bit.

[0008] Furthermore, the ground reinforcement structure of the present invention is a ground reinforcement structure reinforced using the above-mentioned steel pipe reinforcing members, and is characterized in that the steel pipe reinforcing members are driven into the ground during excavation, and some of the blade portions at the multiple locations are positioned within a collapse area where a collapse load acts on the open ground surface side, and other of the blade portions at the multiple locations are positioned within a settlement area forward of the collapse area.

[0009] According to the present invention, by driving a steel pipe with blades into the ground to be reinforced during ground excavation, the blades of the driven steel pipe reinforcing member resist ground collapse, thereby effectively reinforcing the ground. In other words, in the present invention, the blades are located at multiple locations along the axial direction of the steel pipe, so the steel pipe can be driven into the ground with the blades present both in the collapse zone where the collapse load acts on the ground open face side and in the anchorage zone ahead of the collapse zone (opposite the ground open face side). Furthermore, in the present invention, the blade with the largest diameter among the multiple blades is made larger than the outer diameter of the drill bit, so that it is located outside the diameter of the drill bit and can withstand resistance from the ground that maintains its strength, rather than from the weak ground that has been loosened by the passage of the drill bit.

[0010] As a result, the blades in the collapse zone where the collapse load acts rotate toward the open ground surface as the collapse load acts on them. Furthermore, the blades in the anchorage zone rotate in the opposite direction to counteract this rotation, generating a tensile force in the steel pipe reinforcing member, which allows the steel pipe reinforcing member to resist the ground collapse and prevent the open ground surface from collapsing. In other words, in the present invention, after the steel pipe reinforcing member is installed, the blades can be made to effectively act as a resistance to the collapse load, compared to the conventional reinforcement method in which mortar is injected into the ground over the entire reinforced steel pipe to anchor the steel pipe to the ground. This makes it possible to prevent the ground from collapsing at the open ground surface and secure the installation time.

[0011] As described above, in the present invention, by not using mortar or by minimizing the amount of mortar used, it becomes possible for the blades to resist the collapse load of the collapse area. Furthermore, when excavating the ground, the ground is excavated together with the reinforcing steel pipe reinforcing member, but after construction is completed, when the reinforcing steel pipe reinforcing member is removed and discarded, the effort and time required to separate the ground (soil and sand), the steel pipe with the blades, and the mortar can be significantly reduced, thereby improving construction efficiency.

[0013] Also, In this case, the blades can be smoothly rotated in response to the force that the steel pipe reinforcing member receives from the ground in the pipe axis direction. That is, when the inclination angle is 45° or greater, the force that the ground receives in the pipe axis direction is decomposed into a first component force that is in line with the inclination angle of the blades and a second component force that is perpendicular to the blades. As the inclination angle increases, the second component force gradually increases, and the direction of the second component force approaches parallel to the pipe axis, acting as a resistance force that impedes the rotation of the blades. In the present invention, this resistance force that impedes the rotation of the blades can be suppressed, allowing the blades to rotate together with the steel pipe, separate from the drill bit.

[0014] In the steel pipe reinforcing member according to the present invention, it is preferable that the blade portions overlap at least partially with each other when viewed from the pipe axis direction, when the blade portions are adjacent to each other in the circumferential direction.

[0015] In this case, the area of ​​the steel pipe reinforcement member that is supported by the blade portion in the axial direction of the pipe from the ground can be made larger, so that the blade portion can fully support the force that is received from the ground in the axial direction of the pipe, resulting in a greater reinforcing effect.

[0016] In addition, the ground reinforcement method of the present invention may be characterized in that after the steel pipe reinforcement member is driven into the ground, mortar is injected from the steel pipe reinforcement member into a portion of the ground surrounding the steel pipe reinforcement member.

[0017] Furthermore, the ground reinforcement structure according to the present invention may be characterized in that a mortar filling area is provided in a portion of the ground surrounding the steel pipe reinforcement member, the mortar being injected and hardened.

[0018] With this configuration, mortar can be injected into only a portion of the anchoring region, so that a portion of the steel pipe reinforcing member can be reliably anchored to the anchoring region using mortar.

[0019] In the ground reinforcement method according to the present invention, the steel pipe in the portion into which the mortar is injected may be a steel pipe with a depression, a steel pipe with a projection, or a steel pipe with holes.

[0020] By adopting such a configuration, it is possible to improve the adhesion between the mortar and the steel pipe in the mortar-filled area. [Effects of the Invention]

[0021] According to the steel pipe reinforcement member, ground reinforcement method, and ground reinforcement structure of the present invention, the steel pipe reinforcement member can be removed and the components can be separated efficiently when disposed of, thereby improving construction efficiency. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a vertical cross-sectional view showing a ground reinforcement structure according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a side view of a steel pipe reinforcing member used in the ground reinforcing structure shown in FIG. 1. [Figure 3] FIG. 3 is a side view showing the inside of the steel pipe of the steel pipe reinforcing member shown in FIG. 2. [Figure 4] FIG. 2 is a side view showing the tip of the steel pipe reinforcing member. [Figure 5] FIG. 10 is a side view showing blade portions provided at multiple locations on the steel pipe reinforcing member. [Figure 6] FIG. 6 is a cross-sectional view taken along the line AA in FIG. 5. [Figure 7] FIG. 10 is a side view showing a manufacturing method for processing a blade portion into a steel pipe. [Figure 8] FIG. 10 is a cross-sectional view showing an example in which a wing portion is provided in a coupling of a threaded joint. [Figure 9] FIG. 10 is a cross-sectional view showing an example in which a wing portion is provided on a nipple of a threaded joint. [Figure 10] FIG. 10 is a vertical cross-sectional view showing a ground reinforcement structure according to a second embodiment. [Figure 11] FIG. 4 is a vertical cross-sectional view showing the configuration of the steel pipe reinforcing member when mortar is injected. [Figure 12] FIG. 10 is a vertical cross-sectional view showing a ground reinforcement structure according to a third embodiment. [Figure 13] 6 is a diagram showing blade portions provided at a plurality of locations on a steel pipe reinforcing member according to a first modified example, and corresponds to the cross-sectional view taken along line BB in FIG. 5. FIG. [Figure 14] FIG. 10 is a side view of a steel pipe reinforcing member according to a second modified example, in which a steel pipe is provided with blade portions. [Figure 15] FIG. 10 is a side view of another example of a steel pipe reinforcing member in which a steel pipe is provided with blade portions according to the second modified example. DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, a steel pipe reinforcing member, a ground reinforcing method, and a ground reinforcing structure according to embodiments of the present invention will be described with reference to the drawings.

[0024] (First embodiment) The steel pipe reinforcing member 1 according to this embodiment shown in Fig. 1 is used as a long mirror bolt method (tunnel mirror reinforcement method) in which multiple members are driven into the ground G of a tunnel in a substantially horizontal direction within a cross section of the mirror surface Ga in order to reinforce the ground G of the tunnel in a ground reinforcement method, with the aim of preventing the collapse of the mirror surface Ga (ground open surface) of the tunnel face during excavation. This method requires both adhesion to the ground G and tensile strength. Fig. 1 shows a ground reinforcement structure constructed by a ground reinforcement method using multiple steel pipe reinforcing members 1. The steel pipe reinforcing member 1 of this embodiment is made up of a plurality of steel pipes, each of which is, for example, approximately 3 m long, connected in series by connecting joints.

[0025] The ground G in front of the mirror surface Ga (face) is surrounded by a two-dot chain line in Figure 1 and has collapsed soil in the area (collapse area G1) close to the mirror surface Ga, which is the area where the collapse load P acts. The collapse area G1 extends from the front of the mirror surface Ga upward (toward the ground). The extent of the collapse area G1 indicated by the two-dot chain line varies depending on the geological conditions of the ground G and the construction conditions, such as the size and shape of the tunnel cross section (mirror surface Ga). Furthermore, the area in front of the collapse area G1 (away from the mirror surface Ga) is an area where ground collapse is unlikely to occur (anchoring area G2). The steel pipe reinforcing member 1 driven into the ground G from the mirror surface Ga passes through the collapse area G1 and is driven so that the steel pipe reinforcing member 1 is positioned in the anchoring area G2 from its tip to its middle in the longitudinal direction (pipe axis direction X, described below) of the steel pipe reinforcing member 1.

[0026] As shown in Figure 2, in the steel pipe reinforcing member 1, the direction along the central axis of the steel pipe (pipe axis O) is referred to as the pipe axis direction X, the direction perpendicular to the pipe axis O is referred to as the radial direction, and the direction going around the pipe axis O as viewed from the pipe axis direction X is referred to as the circumferential direction. In the pipe axis direction X, the forward side of the driving of the steel pipe reinforcing member 1 is referred to as the front side, forward, or tip side X1, and the opposite side is referred to as the rear side, rear, or base side X2. In the following description, the side of the pipe axis O in the radial direction is referred to as the inside, and the side opposite the inside and away from the pipe axis O is referred to as the outside.

[0027] As shown in Figures 2 and 3, the steel pipe reinforcement member 1 comprises a steel pipe 2 that is driven into the ground G using a ground reinforcement method, a drill bit 3 for ground excavation that is provided at the tip of the steel pipe 2, a casing shoe 4 that is placed between the steel pipe 2 and the drill bit 3, and an inner rod 5 that is placed inside the steel pipe 2 and fixes the drill bit 3 from behind. That is, the steel pipe reinforcing member 1 has an inner rod 5 connected to the drill bit 3, which transmits power from a drilling machine (not shown) located on the base end side X2, and as the inner rod 5 rotates, the ground G is excavated, and the steel pipe reinforcing member 1 is also buried in the ground G.

[0028] The drill bit 3 is provided in front of the casing shoe 4 and is rotatable about the pipe axis O while being separated from the steel pipe 2 and the casing shoe 4. The drill bit 3 is formed in a circular shape when viewed from the front and has multiple cutting bits 31 along the outer periphery of its tip. The drill bit 3 is fixed to the tip of the inner rod 5.

[0029] As shown in Figure 3, the inner rod 5 is used to transmit the rotational driving force from the drilling machine to the drill bit 3 when driving the steel pipe reinforcing member 1 into the ground G, and is provided integrally with the drill bit 3. The inner rod 5 is arranged inside the steel pipe 2 and casing shoe 4. The inner rod 5 comprises a fixing part 51 that fixes and supports the drill bit 3 from the rear, and a rod main body 52 that connects the fixing part 51 to a rotational driving source at the rear (here, for example, the driving device of a drill jumbo). The rod main body 52 has an outer diameter smaller than that of the steel pipe 2, so that it does not come into contact with the steel pipe 2 even when rotated. As the steel pipe 2 is extended, the rod main body 52 is also extended.

[0030] The drill bit 3 and the inner rod 5 rotate integrally while being separated from the steel pipe 2 and the casing shoe 4. The drill bit 3 pulsates back and forth in the pipe axis direction X against the hard rock due to rotation when drilling the ground G. During this process, part of the outer circumferential surface of the inner rod 5 repeatedly collides with the inner circumferential surface of the casing shoe 4.

[0031] The casing shoe 4 is non-rotatably connected to the tip of the steel pipe 2 by a threaded joint. The casing shoe 4 is provided with a pin (not shown) having an external thread on the rear base end side X2.

[0032] As shown in FIG. 4, the steel pipe 2 is independent of the drill bit 3, which rotates during drilling, and can freely rotate around the pipe axis O. In other words, the steel pipe 2 is not constrained by the rotation of the drill bit 3 and is in a state of free rotation. The steel pipe 2 is provided with a box (not shown) having an internal thread machined on the inner surface at the tip side X1, and has an internal thread that is screwed onto the external thread of the pin of the casing shoe 4. For example, the steel pipe 2 may be a carbon steel pipe for general structure specified in JIS G3444 or a carbon steel pipe for building structure. For example, the steel pipe 2 may have an outer diameter of 76.3 mm to 114.3 mm.

[0033] As shown in Figure 5, a plurality of steel pipes 2 used as a steel pipe reinforcing member 1 are connected together by threaded joints 20 consisting of male and female threads as described above, and are connected in series in the pipe axis direction X. For the threaded joints 20 connecting the steel pipes 2 together, in addition to a typical joint with male and female threads, it is possible to use joints using a coupling 2A (see Figure 8) or a nipple 2B (see Figure 9), which will be described later.

[0034] As shown in Fig. 2, a blade group 210 composed of a plurality of blade portions 21 is provided on the outer peripheral surface 2a of the steel pipe 2 at a plurality of locations (three locations in this embodiment) in the pipe axis direction X. In the blade group 210, a plurality of blade portions 21 are arranged along the circumferential direction of the outer peripheral surface 2a of the steel pipe 2. The blade portions 21 protrude radially outward and are inclined with respect to the pipe axis O.

[0035] 5, the blade sets 210 arranged at multiple locations in the pipe axis direction X of the steel pipe 2 include a first blade set 211 on the tip side X1, a second blade set 212 arranged in an intermediate portion in the pipe axis direction X, and a third blade set 213 on the base side X2. Each blade set 210 has the same shape and is inclined in the same direction.

[0036] As shown in Fig. 4, the inclination angle θ of blade portion 21 relative to the tube axis O is set to be greater than 0° and less than 45°. If the inclination angle θ varies within one blade portion 21, the variation range of inclination angle θ is preferably set to be 0°<θ<45°. Blade portion 21 of the present embodiment is inclined and gradually curved counterclockwise from base end side X2 to tip end side X1 when viewed from the rear. The length of the blade portion 21 extending in the pipe axis direction is set appropriately, but it is also possible for the blade portion 21 to extend in a spiral shape.

[0037] In the steel pipe reinforcement member 1, the force received from the ground G (a force directed from the distal end X1 to the proximal end X2 in the pipe axis direction X) is resolved into a first component force F1 along the inclination angle θ of the blade portion 21 and a second component force F2 perpendicular to the blade portion 21. As the inclination angle θ increases, the second component force F2 gradually increases, and the direction of the second component force F2 approaches parallel to the pipe axis O, thereby acting as a resistance force that inhibits the rotation of the blade portion 21. To prevent this, the inclination angle θ of the blade portion 21 in the steel pipe reinforcement member 1 of this embodiment is set in the range of 0°<θ<45°. As shown in FIG. 2 , the steel pipe reinforcement member 1 is configured to smoothly rotate the blade portion 21 around the pipe axis O (in the direction of arrow E1 in FIG. 2 ) in response to the force (collapse load P) received from the collapse region G1.

[0038] 4, the maximum diameter D1 of the plurality of blades 21 is set to be larger than the outer diameter D2 of the drill bit 3. In this embodiment, all of the blades 21 have the same shape, and therefore all of the blades 21 are subject to the maximum diameter D1. As a result, in the steel pipe reinforcing member 1 of this embodiment, the outer periphery 21a of the blades 21 is located radially outward of the outer periphery 3a of the drill bit 3, so that the outer periphery 21a of the blades 21 can be placed outside the loose ground excavated by the drill bit 3 and in ground that is harder than the loose ground that has been excavated by the drill bit 3. In other words, the blades 21 can provide resistance to the hard ground, and after the steel pipe reinforcing member 1 is driven into the ground G, resistance to the collapse load P effectively acts.

[0039] 6, in each blade set 210, at least a portion of adjacent blade portions 21 in the circumferential direction as viewed from the pipe axis direction X overlaps with each other. This overlapping allows blade portions 21 to fully bear the force from the ground G, thereby achieving a higher reinforcing effect.

[0040] As a manufacturing method of the blade portion 21, a method of welding the blade portion 21 members to the steel pipe 2 afterward, or a method of building up the excess weld bead in a blade shape to form the blade portion 21 can be used. Also, as shown in Figure 7, a method can be used in which a steel pipe 2 with an integrally formed straight blade member (the left side of Figure 7) is twisted to form a slope in the blade member to form the blade portion 21 (the right side of Figure 7). When the blade portion 21 is to be sloped in the same direction by twisting, the blade portion 21 before twisting shown in the left side of Figure 7 can be manufactured by the method described above, or a method can be used in which a steel pipe member with blades is integrally molded by hot pipe extrusion and then twisted.

[0041] Figures 8 and 9 show a configuration in which a coupling 2A (see Figure 8) or a nipple 2B (see Figure 9) is used in a threaded joint 20 that connects multiple steel pipes 2 together, and a blade portion 21 is provided on the outer surface of the coupling 2A or nipple 2B.

[0042] In the joint form shown in Fig. 8, a pin 22 is formed at the end of a steel pipe 2. A coupling 2A that connects the pins 22 of the steel pipes 2 to be coupled to each other has boxes 23 at both ends in the pipe axis direction X. Furthermore, blade portions 21 are provided on the outer peripheral surface 2c of the coupling 2A.

[0043] In the joint form shown in Fig. 9, a box 24 is formed at the end of a steel pipe 2. A nipple 2B that connects the boxes 24 of the steel pipes 2 to be coupled together has pins 25 at both ends in the pipe axis direction X. Furthermore, blade portions 21 are provided on the outer peripheral surface 2d between the pins 25 of the nipple 2B.

[0044] In this case, the blade portion 21 is formed for the coupling 2A or nipple 2B, which is shorter and lighter than the steel pipe 2, and therefore the manufacturing efficiency of the components can be improved.

[0045] Next, the functions of the above-described steel pipe reinforcing member 1, ground reinforcing method, and ground reinforcing structure will be described in detail with reference to the drawings. 1 and 2, according to this embodiment, by driving a steel pipe 2 equipped with blade portions 21 into the ground G to be reinforced during tunnel excavation, the blade portions 21 of the driven steel pipe reinforcing member 1 resist collapse of the ground G, thereby effectively reinforcing the ground G. In other words, in this embodiment, the blade portions 21 are present at multiple locations in the pipe axis direction X of the steel pipe 2, so that the steel pipe 2 can be driven into the ground G with the blade portions 21 present both in the collapse region G1 on the mirror surface Ga side where the collapse load acts, and in the anchorage region G2 in front of the collapse region G1 (opposite the mirror surface Ga side).

[0046] Furthermore, in this embodiment, the blade portion 21 with the largest diameter among the multiple blade portions 21 is made larger than the outer diameter of the drill bit 3, so that it is positioned outside the diameter of the drill bit 3 and can withstand resistance from the ground G that maintains its strength, rather than from the low-strength ground that has become loosened by the passage of the drill bit 3.

[0047] As a result, as shown in Figure 2, the blades 21 located within the collapse region G1 where the collapse load P acts rotate in a first direction E1 so as to approach the mirror surface Ga in response to the action of the collapse load P. Furthermore, the blades 21 located within the anchorage region G2 rotate in the opposite direction, in a second direction E2, to counteract this rotation in the first direction E1. This generates tensile forces T1 and T2 in the steel pipe reinforcing member 1, which resist the collapse region G1 and provide reinforcement that prevents the collapse of the mirror surface Ga. Here, the tensile forces acting on the steel pipe reinforcing member 1 are denoted by the symbol T1 for the tensile force acting on the base end side X2, and the tensile force acting on the tip end side X1 is denoted by the symbol T2. That is, in this embodiment, after the construction of the steel pipe reinforcing member 1, compared to the conventional reinforcement method in which mortar is injected into the ground G over the entire reinforced steel pipe to anchor the steel pipe to the ground G, the blade portion 21 can be made to effectively act as a resistance to the collapse load P. This makes it possible to prevent the ground G at the mirror surface Ga from collapsing, and ensures time for tunnel construction.

[0048] In this embodiment, as described above, by not using mortar or by minimizing the amount of mortar used, it becomes possible for the blade portions 21 to resist the collapse load P of the collapse region G1. Furthermore, when excavating a tunnel, the ground G is excavated together with the reinforcing steel pipe reinforcing member 1, but after the tunnel construction is completed, when the reinforcing steel pipe reinforcing member 1 is removed and discarded, the effort and time required to separate the ground (earth and sand), the steel pipe 2 equipped with the blade portions 21, and the mortar can be significantly reduced, thereby improving construction efficiency.

[0049] Furthermore, in this embodiment, as shown in Figure 4, by making the inclination angle θ of the blade portion 21 with respect to the pipe axis O greater than 0° and less than 45°, the blade portion 21 can be smoothly rotated in response to the force that the steel pipe reinforcing member 1 receives from the ground G in the pipe axis direction X. As a result, in this embodiment, the resistance force that inhibits the rotation of the blade portion 21 can be suppressed, and the blade portion 21 can be rotated together with the steel pipe 2 separately from the drill bit 3.

[0050] 6, adjacent blades 21 in the circumferential direction as viewed from the pipe axis direction X at least partially overlap with each other, which increases the area over which the steel pipe reinforcing member 1 receives force from the ground G in the pipe axis direction X at the blades 21. This allows the blades 21 to fully receive the force from the ground G in the pipe axis direction X, thereby achieving a higher reinforcing effect.

[0051] The steel pipe reinforcement member 1, ground reinforcement method, and ground reinforcement structure according to the present embodiment described above enable the steel pipe reinforcement member 1 to be removed and the components to be separated when disposed of efficiently, thereby improving construction efficiency.

[0052] (Second embodiment) As shown in FIG. 10 , the ground reinforcement method according to the second embodiment is a method in which a steel pipe reinforcing member 1 is driven into the ground G, and then mortar 11 is injected from the steel pipe reinforcing member 1 into only a portion of the ground G surrounding the steel pipe reinforcing member 1 (in the second embodiment, the tip portion of the steel pipe reinforcing member 1). That is, the ground reinforcement structure 10A according to the second embodiment has a structure in which a mortar filling area 11A is provided, which is injected into the tip portion of the ground G surrounding the steel pipe reinforcing member 1 and hardened. The tip portion (mortar filling area 11A) into which the mortar 11 is injected is part of the anchorage area G2 of the steel pipe reinforcing member 1.

[0053] As shown in FIG. 11 , in the second embodiment, when driving a steel pipe reinforcement member 1 into the ground G and injecting mortar 11, a mortar injection pipe 26 equipped with a packer 27 is inserted into the steel pipe 2. An injection port 28 is provided at the tip of the steel pipe 2 for injecting mortar 11 from inside the steel pipe toward the ground G. A plurality of injection ports 28 are provided at intervals in the circumferential direction. After driving the steel pipe reinforcement member 1, the inner rod 5 (see FIG. 2 ) is withdrawn to the base end side X2, and the mortar injection pipe 26 is instead inserted into the steel pipe 2 from the base end side X2. The tip 26a of the mortar injection pipe 26 set inside the steel pipe 2 is positioned rearward (on the base end side X2) from the injection port 28. The packer 27 is positioned rearward (on the base end side X2) of the tip 26a of the mortar injection pipe 26 so as to shield the interior of the steel pipe 2 from the front and rear.

[0054] Mortar 11 is discharged from tip 26a of mortar injection pipe 26, filling the tip side of packer 27 as shown by the arrow in Figure 11, and is then injected into the ground G from injection port 28. In this way, by filling mortar 11 in mortar filling area 11A, part of the ground G at the anchorage part of steel pipe reinforcing member 1 is reinforced with mortar 11.

[0055] In addition, as the steel pipe 2 of this second embodiment, it is also possible to use a pre-processed steel pipe such as a recessed steel pipe, a protruding steel pipe, or a perforated steel pipe, which has an uneven shape formed on the outer surface 2a, with the aim of increasing the adhesion between the mortar 11 and the steel pipe 2 in the mortar filling area 11A.

[0056] As shown in Figure 10, in this second embodiment, mortar 11 can be injected into only a portion of the anchoring area G2, so that a portion of the steel pipe reinforcing member 1 can be reliably anchored to the anchoring area G2 using mortar 11. Furthermore, since the mortar filling area 11A into which the mortar 11 is injected in the ground G is a partial range in the steel pipe reinforcing member 1, it is possible to prevent the loss of resistance of the steel pipe 2 due to the rotation of the blades 21. In other words, since the mortar filling area 11A is limited, the rotation of the blades 21 arranged in the collapse area G1 where the collapse load P acts can generate resistance in the steel pipe 2, thereby achieving effective reinforcement as described above.

[0057] Moreover, in the second embodiment, although reinforcement is performed using mortar 11, the amount of mortar 11 used is limited. Therefore, the effort required for removing the steel pipe reinforcing member 1 and separating the members when disposing of it is somewhat less than when mortar is not used, but construction efficiency can be improved compared to the conventional case in which mortar is injected throughout the entire steel pipe reinforcing member.

[0058] (Third embodiment) Next, the third embodiment shown in Fig. 12 is an application of a steel pipe reinforcing member 1 to a long forepile method (steel pipe forepiling method) that prevents the collapse of the top of the tunnel. That is, in the first embodiment described above, a configuration in which the steel pipe reinforcing member 1 is driven into the ground G in a substantially horizontal direction from the mirror surface Ga is described using the tunnel mirror reinforcement method as an example, but in the third embodiment, the steel pipe reinforcing member 1 is driven diagonally forward from the upper end portion of the mirror surface Ga.

[0059] In the third embodiment, a steel pipe reinforcing member 1 is used that includes a steel pipe having a blade portion similar to that of the first and second embodiments described above, and resistance is generated in the steel pipe reinforcing member 1 as the blade portion rotates together with the steel pipe in the collapse region G1 where the collapse load P acts.

[0060] (First Modification) As shown in Figure 13, in the steel pipe reinforcing member 1A according to the first modified example, the circumferential mounting positions of the blade portions 21 of the first blade group 211 are different from the circumferential mounting positions of the blade portions 21 of the second blade group 212. The first blade group 211 and the second blade group 212 each have four blade portions 21 arranged at equal intervals in the circumferential direction. When viewed from the tip side X1, the steel pipe reinforcing member 1A is arranged such that at least a portion (here, the portion on the steel pipe 2 side, the radially inner portion) of the blade portions 21 of the second blade group 212 overlaps between circumferentially adjacent blade portions 21, 21 of the first blade group 211.

[0061] In the first modified example, by giving blade portion 21 such a blade shape, blade portion 21 can withstand the force from ground G without any surplus, and a higher reinforcing effect can be obtained.

[0062] (Second Modification) Next, steel pipe reinforcing members 1B and 1C according to a second modification shown in FIGS. 14 and 15 have blade portions 21A and 21B with different shapes. The blade portions 21A of the steel pipe reinforcing member 1B shown in Fig. 14 extend linearly in the inclined direction and are provided on the outer peripheral surface 2a of the steel pipe 2. That is, the blade portions 21A are flat plate-shaped.

[0063] The blade portion 21B of the steel pipe reinforcing member 1C shown in Fig. 15 has a curved direction (inclination direction) that is opposite to the circumferential direction of the blade portion 21 (see Fig. 2) of the first embodiment described above. That is, the blade portion 21B is gradually curved and inclined in a clockwise direction from the base end side X2 toward the tip end side X1 when viewed from the rear.

[0064] The above describes embodiments of the steel pipe reinforcement member, ground reinforcement method, and ground reinforcement structure according to the present invention, but the present invention is not limited to the above embodiments and can be modified as appropriate within the scope of the spirit thereof.

[0065] For example, in this embodiment, a steel pipe reinforcing member 1 is adopted that is configured so that the inclination angle θ of the blade portion 21 relative to the pipe axis O is greater than 0° and less than 45°, but the inclination angle θ of the blade portion 21 may also be 45° or more.

[0066] Furthermore, the blade portions 21 are not limited to being at least partially overlapped with each other when viewed from the pipe axis direction X, as in the present embodiment, and adjacent blade portions 21 may be spaced apart with a gap therebetween.

[0067] Furthermore, in this embodiment, the plurality of blade portions 21 arranged in the circumferential direction in the blade set 210 all have the same shape, but this is not limited to this. Blade portions 21 of a plurality of different shapes may be arranged in the same blade set 210.

[0068] Furthermore, in the second embodiment described above, the reinforcement method involves injecting mortar 11 into the tip of the steel pipe reinforcement member 1, but the filling position of the mortar 11 is not limited to the tip of the steel pipe reinforcement member 1 as long as it is within the anchorage area G2.

[0069] Furthermore, in this embodiment, tunnel construction has been used as an example of the steel pipe reinforcement member, ground reinforcement method, and ground reinforcement structure to which the present invention is applied, and construction in which a steel pipe is driven horizontally into the ground has been described. However, the application of the steel pipe reinforcement member, ground reinforcement method, and ground reinforcement structure of the present invention is not limited to tunnels. For example, the steel pipe of the present invention can also be applied to piles that are driven vertically into the ground. In other words, there is no restriction on the direction in which the steel pipe is driven into the ground, and the construction target for reinforced ground can be tunnel construction as in this embodiment, as well as pile construction.

[0070] In addition, the components in the above-described embodiments can be replaced with well-known components as appropriate, without departing from the spirit of the present invention. [Explanation of symbols]

[0071] 1 Steel pipe reinforcement member 2 Steel pipe 2a Outer surface 3 drill bits 4 Casing shoe 5 Inner rod 10 Ground reinforcement structure 11 Mortar 21, 21A, 21B Blades 210 Feather group G Ground Ga Mirror surface (open ground surface) G1 Collapsed Region G2 Fixation area P collapse load X Tube axis direction X1 Tip side X2 proximal side

Claims

1. A steel pipe reinforcing member that is driven into the ground to reinforce it in order to prevent the ground from collapsing during excavation, A steel pipe driven into the ground; a drill bit for excavating ground that is rotatably provided at the tip of the steel pipe while being separated from the steel pipe; a group of blades provided at a plurality of locations on the outer peripheral surface of the steel pipe at intervals in the axial direction of the steel pipe; Equipped with Each of the blade groups has a plurality of plate-shaped blade portions inclined with respect to the tube axis, The blade portion is attached such that the inclination angle of the plate surface with respect to the tube axis is greater than 0° and less than 45°, and the height in the radial direction is set to be greater than the plate thickness, The diameter of the steel pipe is smaller than the diameter of the drill bit, A steel pipe reinforcing member characterized in that the blade with the largest diameter among the plurality of blades is larger than the outer diameter of the drill bit.

2. The steel pipe reinforcing member according to claim 1, wherein the blade portions are arranged so that adjacent blade portions in the circumferential direction overlap at least partially when viewed from the pipe axial direction.

3. A ground reinforcement method using the steel pipe reinforcing member according to claim 1 or 2, A ground reinforcement method, characterized in that the steel pipe provided with the blade portion is driven into the ground while the drill bit is rotated.

4. 4. The ground reinforcement method according to claim 3, wherein after the steel pipe reinforcement member is driven into the ground, mortar is injected from the steel pipe reinforcement member into a portion of the ground surrounding the steel pipe reinforcement member.

5. 5. The ground reinforcement method according to claim 4, wherein the steel pipe in the portion into which the mortar is injected is a steel pipe with a depression, a steel pipe with a projection, or a steel pipe with holes.

6. A ground reinforcement structure reinforced using the steel pipe reinforcing member according to claim 1 or 2, The steel pipe reinforcing member is driven into the ground during excavation, Some of the blade portions at the plurality of locations are arranged within a collapse area where a collapse load acts on the ground open surface side, A ground reinforcement structure characterized in that other of the multiple blade portions are located within a settlement area forward of the collapse area.

7. 7. The ground reinforcement structure according to claim 6, wherein a mortar filling area is provided in a portion of the ground surrounding the steel pipe reinforcing member, the mortar being injected and hardened.

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