JP6220602B2 - Ground anchor and ground anchor method - Google Patents

Description

  The present invention relates to a ground anchor that stabilizes a structure using a tensile force. The present invention also relates to a ground anchor method using the anchor.

Conventionally, a shield construction method using a shield excavator has been frequently used as a tunnel construction such as a subway, a railway, a common ditch, and a sewer.
In this shield method, first, a vertical shaft (starting shaft) is formed by an open-cut method, a shield excavator is carried underground from this starting shaft, and the excavation side of the starting shaft is excavated with the shield excavator. It is a construction method that allows the formation of a tunnel by starting in the lateral direction and excavating to the end point as the destination point. In such a shield method, a vertical hole (reach shaft) similar to the above-described start shaft is formed at the end point as the destination point, and the shield excavator is made to reach the reach shaft.

  By the way, the side wall of the start shaft and the reach shaft (hereinafter collectively referred to as the shaft) formed by the open-cut method, the collapse of the wall surface due to earth pressure or water pressure (hereinafter referred to as earth pressure, etc.) In order to prevent groundwater from flowing out, earth retaining walls, which are temporary walls using reinforced concrete, groove sheet piles, H-section steel, etc., are constructed. In some cases, measures such as improving the surrounding ground are also taken.

As described above, the shield shaft is provided with a retaining wall for holding a space against earth pressure or the like. In addition, the earth retaining wall thus formed usually has to be formed with an opening when the shield excavator starts and reaches (so-called mirror cutting). Conventionally, for the mirror cutting work of the retaining wall, means by heavy machinery or human power have been taken. On the other hand, as described above, the earth retaining wall is provided so as to oppose the earth pressure and the like, and thus providing an opening or the like may reduce the resistance against the earth pressure and the like.
Under such circumstances, in the construction site, there has been anxiety about safety at the time of work, prolonged construction period, and increased construction costs.

Therefore, in recent years, a member made of a resin molded body reinforced with fibers (for example, FRP (Fiber reinforced plastics)) is incorporated into the earth retaining wall of the shaft, and a portion of this resin molded body (to enable cutting) A shield construction method (abbreviated as SEW construction method: Shield Earth Retaining Wall System) is being implemented.
For example, Patent Document 1 discloses the technique.

Japanese Patent No. 2821556

However, in the conventional SEW method, it has been difficult to employ a retaining wall having a cutting enable region in an environment where earth pressure or the like exceeding a predetermined level is generated. In other words, in an environment where the depth is deeper than a certain level from the ground, the earth pressure applied to the retaining wall becomes excessively large, and the amount of bending of the cuttable region that is a part of the retaining wall increases significantly. There was a concern about the decline and safety issues.
In addition, the same problem has been a concern when the area that can be cut has a predetermined size (larger cross section).

  Therefore, in order to enable the adoption of the SEW method even in such a severe environment, a measure for increasing the thickness of the foamed resin molded body used in the cuttable region and directly reinforcing the bending strength of the cuttable region ( Hereinafter, the measure for increasing the member thickness is taken into consideration. However, when this measure for increasing the thickness of the member is adopted, there is a concern that the material cost of the foamed resin molded body is greatly increased, which is uneconomical.

  Therefore, as another measure, the present inventor considered a measure (hereinafter referred to as an anchor reinforcement measure) of indirectly reinforcing the bending strength of the cuttable region using an anchor. Specifically, this anchor reinforcement measure utilizes a known ground anchor method, and reinforces the cuttable region by a tensile force generated in a long tendon. In this anchor reinforcement measure, a material that can be cut (for example, resin mixed with fibers) is used for tendons and other members that constitute the anchor, and along with cutting of the cuttable area by a shield excavator, Cutting is possible. As a result, the material cost can be suppressed more than the above-described measures for increasing the thickness of the member while ensuring a higher workability than the conventional SEW method.

  However, when this improved measure was adopted, there was a risk of causing poor work during excavation.

  Generally, in the ground anchor method, a tendon is arranged so as to straddle the structure to be stabilized and the ground, and a tensile force is generated in the tendon in this state, so that the structure and the ground are integrated. Is. More specifically, the tendon is partly fixed on the ground by a grout material or the like (referred to as a fixing length), and the other part is not fixed by the grout material or the like (referred to as a free length). To be. And the tendon installed in this way is pulled artificially from the structure side, the tension | tensile_strength is given to a free length part, and the anchor function is exhibited. That is, in the ground anchor method, it is important that the tendon has a free length.

  And in the anchor reinforcement measures used for the above-mentioned cuttable region, the same method is used, and a tensile force is generated in the free length of the tendon, and the bending strength of the cuttable region is reinforced by the tensile force. Is planned.

  However, when cutting a cuttable area with a shield excavator, there is a possibility that the free length provided in the tendon may get entangled with the face of the shield excavator, and the entanglement may cause the shield excavator to malfunction. Was holding.

  Therefore, in the present invention, even when a retaining wall is reinforced and the retaining wall is directly cut by a shield excavator, a ground anchor that does not cause a malfunction due to tendon in the shield excavator In addition, an object is to provide a ground anchor method.

The invention according to claim 1, which is provided to solve the above-mentioned problem, is a ground anchor that is disposed across the structure and the ground and stabilizes the structure, and is disposed on the structure side. A tension side member that is partly or entirely exposed to the outside, a tensile force transmission member that is arranged to straddle the structure and the ground, and a space forming member. The force transmission member has a long shape, one end in the longitudinal direction is integrally joined to the tension side member, and a free length portion in which a tensile force is generated by an external force at a position in the longitudinal direction. The space forming member has a space that covers part or all of the free length portion of the tensile force transmission member, and the space directly or indirectly through the through hole of the tension side member. Te, which communicates with the outside, have a deformable bag body, the bag The tensile force transmission member is arranged so as to cover from the other end portion in the longitudinal direction of the tensile force transmission member to the vicinity of the joint portion between the tensile force transmission member and the tensile side member, and the tensile force transmission member is disposed inside the bag body. It is a ground anchor characterized by being fixed to the ground by the solidified material injected into the ground.
The term “communication with the outside directly or indirectly through the through hole” here means that the through hole is in a state where the space and the outside communicate with each other, and some sort of arrangement of the through hole. It is a concept that includes both the meaning that the hole of the member communicates the space and the outside.

As explained earlier, the ground anchor has a part of the tensile force transmission member placed on the ground fixed (fixed length) by a solidified material such as grout material, and the other part fixed by this solidified material. No free state (free length). And the ground anchor installed in this way is pulled artificially from the structure side via the tension | pulling side member, the tension | tensile_strength is given to a free length part, and the anchor function is exhibited. That is, in a ground anchor that applies a tensile force to the free length portion, it is important to have the free length portion in the tensile force transmission member, and without this, the function as an original anchor cannot be achieved.
On the other hand, in the SEW method for constructing a tunnel, when a cutable area of the retaining wall is reinforced with a ground anchor and the cuttable area is cut with a shield excavator, the free length may be entangled with the face. . That is, the free length portion has an excessively small or almost no rigidity against an external force in a direction intersecting the axial direction (for example, a wire), so that the free length portion may be caught in the rotation of the face of the shield excavator. It was. As a result, there was a risk that the workability of tunnel construction would be significantly reduced.

Therefore, in the ground anchor of the present invention, after applying a tensile force to the free length portion of the tensile force transmission member, even if it is cut by the rotation of the face of the shield excavator, the grout material etc. It is configured to be solidified by solidifying material. That is, according to the present invention, a through-hole is provided in a tension side member that is arranged on the structure side and exposed to the outside, and a space that covers a part or all of the free length portion is provided in the tensile force transmission member. The space is communicated with the outside directly or indirectly. And, in the present invention, a solidified material such as a grout material can be easily injected into the space after a tensile force is applied to the free length portion using a through hole regardless of whether directly or indirectly. It is possible. That is, in the ground anchor of the present invention, the free length portion can be solidified in a state where a tensile force is generated in the free length portion and the anchor function is exhibited.
As a result, even when the ground anchor of the present invention is used for the retaining wall of the SEW method, there is no possibility of causing a problem that the free length portion of the tensile force transmission member is entangled with the face of the shield excavator.

  Moreover, in this invention, when cutting with a shield excavator, since it is not necessary to form the hole etc. for inject | pouring a solidification material in a space formation member, high workability | operativity can be ensured. Similarly, it is not necessary to form a hole or the like for injecting the solidifying material on the pressure receiving plate or the like used when applying a tensile force to the tensile force transmitting member. It is possible to prevent the strength of the plate and the like from being lowered, and to ensure high reliability of the ground anchor.

  The invention according to claim 2 includes a pipe member, and the pipe member is inserted through the through hole, and exposes one end portion thereof to the outside and forms the other end portion as a space. It is the arrangement | positioning exposed in the space of the member, The ground anchor of Claim 1 characterized by the above-mentioned.

  According to this configuration, since the pipe member is arranged in the through hole provided in the tensile force transmission member so as to communicate the inside and outside of the space forming member, the solidification material is injected more efficiently into the space. can do.

The invention according to claim 3 is the ground anchor according to claim 2, wherein the tensile force transmitting member is inserted through the through-hole of the tensile side member together with the pipe member.
According to this configuration, since the tensile force transmission member and the pipe member are inserted into the through hole of the tension side member, the three members can be reasonably joined. For example, if some adhesive (for example, expanded mortar) is injected into the through hole with the tensile force transmission member and the pipe member arranged in the through hole of the pull side member, these three members can be easily integrated. can do.

  In the ground anchor of the present invention, it is recommended that the tensile force transmission member is constituted by a plurality of long members, and the plurality of long members are arranged so as to cover the periphery of the pipe member. (Claim 4)

The present invention has a deformable bag body, and the bag body covers from the other end in the longitudinal direction of the tensile force transmitting member to the vicinity of the joint portion between the tensile force transmitting member and the tensile side member. The tensile force transmitting member is fixed to the ground by a solidifying material injected into the bag body .

  According to this configuration, the predetermined region of the tensile force transmission member is covered with the bag, the solidifying material is injected into the bag, and the tensile force transmission member is fixed to the ground. It is possible to suppress the solidified material flowing out. That is, according to the present invention, even if the tensile force transmitting member is fixed to the ground using the solidifying material, there is almost no adverse effect that can affect the surrounding environment.

Conventionally, as a tension member used for a ground anchor, a metal member is often used as is well known. However, in the SEW method, when a cuttable region is reinforced using a metal pulling side member, when cutting the cutable region with a shield excavator, work such as removing the pulling side member is required, There was a risk of reducing the overall work efficiency.
Therefore, the invention of claim 5 is provided in order to ensure the working efficiency at the time of cutting, tension-side member, according to claim 1, wherein it is a resin molded article reinforced with long fibers It is a ground anchor in any one of.

  According to such a configuration, the tension-side member can be directly cut by the shield excavator, so that the operation such as removing the tension-side member can be omitted. As a result, it is possible to improve work efficiency during cutting by the shield excavator.

According to a sixth aspect of the present invention, after a ground anchor in which a tension side member and a tensile force transmission member are joined in series is inserted into an anchor hole, a solidified material is inserted into the hole from between the ground anchor and the wall surface of the hole. And fixing the fixing length portion of the tensile force transmitting member in the hole, applying an external force to the tensile side member to generate a tensile force at the free length portion of the tensile force transmitting member, Using the provided through-holes directly or indirectly, injecting a solidifying material into a space covering a part or all of the free length portion and solidifying the free length portion where the tensile force is generated A ground anchor construction method characterized in that the ground anchor has a deformable bag body, and the bag body extends from the other end in the longitudinal direction of the tensile force transmission member to the tensile force transmission member and the tension side. Covers the vicinity of the joint with the member Unishi are arranged Te, in the step of fixing the fixing length portion into the hole, the tensile force transmitting member, the ground anchor method, characterized in that fixed to the ground by the solidified material that is injected into the bag body portion It is.

In the ground anchor method of the present invention, after a tensile force is generated in the free length portion of the tensile force transmission member, the through hole provided in the tensile side member is directly or indirectly used to communicate with the through hole. The free length can be hardened by injecting a solidifying material into the space covering the free length. Thereby, in this invention, even if it cuts a free length part by rotation of the face of a shield excavator, it is suppressed that the said free length part gets entangled with a face. Moreover, in this invention, after generating a tensile force in a free length part, since a free length part is hardened, an anchor function is not lost.
Therefore, even when the ground anchor method of the present invention is employed in the method of reinforcing the retaining wall of the SEW method, the free length portion of the tensile force transmission member is secured to the face of the shield excavator while securing the anchor function. It is possible to suppress problems such as tangling.

  The ground anchor and the ground anchor method of the present invention generate a tensile force with respect to the free length portion of the tensile force transmission member even when the ground anchor method is employed in the method of reinforcing the retaining wall of the SEW method. Therefore, since it can be hardened with a solidified material such as a grout material, there is a low possibility that a trouble such as the free length portion of the tensile force transmitting member tangled with the face of the shield excavator will occur.

It is a conceptual diagram which shows the state which installed the ground anchor which concerns on embodiment of this invention in the earth retaining wall. It is a perspective view which shows the ground anchor shown in FIG. It is a disassembled perspective view which shows the ground anchor shown in FIG. It is the disassembled perspective view which paid its attention to the grip main body shown in FIG. 3, a tendon, and a pipe member. It is a longitudinal cross-sectional view which shows the grip main body shown in FIG. It is a longitudinal cross-sectional view which shows the ground anchor of FIG. It is AA sectional drawing which shows the ground anchor of FIG. It is a front view which shows an anchor reinforcement area | region. It is explanatory drawing which showed concretely the construction method of a retaining wall, (a) shows the state which inserted the ground anchor in the anchor fixing hole, (b) shows the state which inject | poured the solidification material into the anchor fixing hole , It is explanatory drawing which showed concretely the construction method of a retaining wall, (a) shows the state which set the pressure-receiving board, (b) shows the state which is keeping tension | tensile_strength in tendon using a nut etc. Show. It is explanatory drawing which showed concretely the construction method of a retaining wall, (a) shows the state which has inject | poured the solidification material into the free length part sheath, (b) is the solidification material in the free length part sheath. It shows a fully satisfied state. It is explanatory drawing which showed the construction method of the earth retaining wall concretely, and has shown the completed state. It is sectional drawing which shows the modification of a ground anchor, (a) shows the state which arranged the tendon and the pipe member on the same periphery, (b) shows the state which arranged tendon on the fixed place. It is a perspective view which shows the principal part of the earth retaining wall used for a SZ pile construction method. It is a perspective view which shows the principal part of the earth retaining wall used for a NOMST (trademark) construction method.

Below, the ground anchor which concerns on embodiment of this invention is demonstrated.
The ground anchor 1 according to the present embodiment can reinforce the retaining wall 31 of the shaft 30 formed when excavating the shield tunnel, and has a function that can be cut together with the retaining wall 31 by the shield excavator S. Is. That is, the ground anchor 1 of the present embodiment has a cut tendon (tensile force transmission member) 3 and is suitable as an anchor used in the ground anchor method. As shown in FIG. This is suitable for reinforcing a cutting portion (hereinafter referred to as a cuttable region 11) of the retaining wall 31 used in the SEW method (Shield Earth Retaining Wall System).

  And the ground anchor 1 of this embodiment has a tendon grip (tensile side member) 2 and a tendon (tensile force transmission member) 3 as main components as shown in FIGS. As shown, a free length sheath (space forming member) 5 and a friction packer (bag body) 6 are provided.

  The tendon grip (tensile side member) 2 is a resin molded product whose main part is formed of fiber reinforced plastics (FRP), and as shown in FIG. 4, two cylinders a and b having different diameters are used. Have a grip body 15 combined in series. In this embodiment, the grip body 15 is a resin molded product reinforced with glass fibers, but may be a resin molded product reinforced with other fibers such as carbon fibers. Absent.

  The grip body 15 is formed such that the cylinder a has a larger outer diameter than the cylinder b and is longer than the length of the cylinder b in the axial direction. The cylinder a is threaded on the outer periphery to form a male threaded portion 22. Further, spaces extending in the axial direction are provided in the cylinders a and b, respectively, and as shown in FIG. 5, through holes 21 penetrating in the axial direction are formed by these spaces.

In this embodiment, a metal or resin tube member 7 is joined to the grip body 15. The pipe member 7 is a member having a certain length, and the axial length thereof is longer than the total value of the axial lengths of the grip body 15. Further, the outer diameter of the tube member 7 is smaller than the inner diameter of the through hole 21 so that the grip body 15 can be inserted into the through hole 21.
The pipe member 7 is inserted into the through hole 21 of the grip body 15 and is integrally joined to the grip body 15 in this state. In this embodiment, as the joining means, an expansion mortar or the like is used. An expansion material G is used.

The tendon (tensile force transmission member) 3 is constituted by a long wire member (long member) 16 having a plurality of (six in this embodiment) predetermined lengths. In this embodiment, as each wire member 16, a cable made of FRP, specifically, a cable in which a plurality of core wires having carbon fibers are bundled is employed.
In addition, as a core wire which comprises each wire member, you may have a glass fiber.

The tendon 3 is divided into three ranges for each role (main role). That is, the tendon 3 is divided along the longitudinal direction as shown in FIG. Specifically, the section includes, in order from one end side in the longitudinal direction, a portion p (hereinafter referred to as a joint portion) that is integrally joined to the tendon grip 2 and a portion where a tensile force is generated by an external force ( A free length portion q and a portion (fixing length portion) r fixed to the ground or the like.
The tendon 3 is inserted into the through hole 21 of the grip body 15 together with the pipe member 7 described above, and is integrally joined by the expansion material G.

  The free length portion sheath (space forming member) 5 is a cylindrical body having a certain length, and is mainly used so as to cover the outer peripheral side of the free length portion q of the tendon 3. In the present embodiment, a bellows-like cylindrical body formed of resin is employed as the free-length portion sheath 5. That is, the free-length sheath 5 is a member having an outer peripheral surface that is uneven in the axial direction and is provided with stretchability in the axial direction.

  As shown in FIGS. 3 and 6, the friction packer 6 is an elongated bag made of cloth or nylon. In this embodiment, the total length of the friction packer 6 is approximately the sum of the fixing length r and the free length q of the tendon 3. The length is almost the same.

Then, the positional relationship of each member which comprises the ground anchor 1 of this embodiment is demonstrated.
The ground anchor 1 of this embodiment has a tendon grip 2 and a tendon 3 as main components, and they are arranged in series and joined together. That is, as shown in FIG. 6, the tendon 3 is provided with a joint p divided on one side in the longitudinal direction in the through hole 21 of the grip body 15 and is injected into the through hole 21. It is joined by the expanded material G. At the same time, in this embodiment, the pipe member 7 is inserted through the through hole 21 of the grip body 15 and joined to the grip body 15 together with the tendon 3. The tube member 7 is joined to the grip body 15 in a posture in which both ends protrude from the through hole 21.

  The tendon 3 and the pipe member 7 joined to the grip body 15 are in a predetermined arrangement in the through hole 21. That is, as shown in FIG. 7, each wire member 16 of the tendon 3 is arranged so that the tube member 7 is arranged at the center of the through hole 21 of the grip body 15 and is substantially equidistant in the circumferential direction of the tube member 7. Are lined up. The expansion material G is filled between the gaps of the through holes 21, that is, between the tendon 3 and the pipe member 7 and the wall surfaces forming the through holes 21.

A free length sheath 5 which is a part of the auxiliary structure is connected to the tendon grip 2 of the main structure forming the ground anchor 1. In other words, the free-length sheath 5 has an arrangement in which one end is abutted against the grip body 15 while the tendon 3 is disposed in the space in the cylindrical body. That is, the free length sheath 5 extends from one end side (grip body 15) of the joining portion p of the tendon 3 to a position in the longitudinal direction of the tendon 3 (in the present embodiment, substantially the free length q of the tendon 3). (Overall). At the same time, since one end portion side of the tube member 7 exposed from one end portion in the axial direction of the grip body 15 is also arranged in the free length portion sheath 5 in the space, The tube member 7 communicates with the inside and outside. And the predetermined | prescribed water stop material 23 is attached to the free length part sheath 5 so that the other edge part (edge part facing the junction part p of tendon 3) may be obstruct | occluded.
In addition, the water stop material 23 is the same as that of a well-known thing, and what was shape | molded by the foaming silicon etc. is employ | adopted.

  In the present embodiment, the friction packer 6 that is the remaining part of the auxiliary structure is arranged so as to cover almost the entire free length portion q from the fixing length portion r. More specifically, the friction packer 6 has one end portion (open side end portion) arranged on the joint p side in the free length portion q and the other end portion (closed side end portion) of the fixing length portion r. It is located at a position slightly away from the center. Then, in order to attach the friction packer 6 to the tendon 3, the friction packer 6 is tightened from the outer peripheral side of the friction packer 6 using attachment means (not shown) (for example, a vinyl tape and a binding band).

  Next, the construction method of the earth retaining wall reinforced with the ground anchor of this embodiment is demonstrated.

First, the retaining walls 31a and 31b which are the side walls of the shaft 30 (FIG. 1) having a square shape in plan view are constructed by using a known soil cement method. At this time, a cutable region 11 that can be directly cut by the shield excavator S is formed on the earth retaining wall 31b corresponding to the starting direction of the shield excavator S.
At this time, since the cuttable region 11 is not reinforced by the ground anchor 1, the cuttable region 11 before reinforcement is hereinafter referred to as a pre-reinforcing cutting region 11a (FIGS. 9 to 11).

  Here, the earth retaining wall 31b provided with the cutable area 11 will be described. As shown in FIG. 8, the earth retaining wall 31b has a plurality of long resin bodies in a portion where the area that can be cut 11 is located. 40 is disposed, and the metal member 41 is disposed in the other part (non-cutting region). More specifically, the earth retaining wall 31b is arranged so that a plurality of metal members 41 are juxtaposed in a posture in which the metal members 41 are extended in the vertical direction (height direction), and a partial range thereof is defined as a cuttable region 11. . And the earth retaining wall 31b arranges a non-cutting region on the top, bottom, left and right of this cutable region 11, and in order to make the cuttable region 11 and the non-cutting region integral, especially at the vertical position in the height direction. The long resin body 40 and the metal member 41 are connected by fastening elements such as a joint and a bolt and nut (not shown). A soil cement hardened body 42 is filled between the long resin bodies 40 arranged in this manner and the metal member 41. That is, the earth retaining wall 31 b is formed by combining the long resin body 40, the metal member 41, and the soil cement hardened body 42.

On the other hand, the earth retaining wall that does not have the cutable region 11 is formed by only the plurality of metal members 41 and the hardened soil cement 42.
In this embodiment, the long resin body 40 is made of polyurethane foam resin (FFU: Fiber reinforced foamed urethane) reinforced with long glass fibers, and the metal member 41 is made of H-shaped steel. It has been adopted.

Thus, when the retaining walls 31a and 31b are completed, the part surrounded by the retaining walls 31a and 31b is excavated (vertical excavation) with a predetermined excavator.
The shaft 30 is provided with a known cut beam (not shown) at a certain depth in order to counteract earth pressure and water pressure (hereinafter simply referred to as earth pressure) applied to the retaining walls 31a and 31b.

  Then, when the shaft excavation is carried out and the excavation progresses to the middle in the height direction of the pre-reinforcing cutting region 11a, the process shifts to the ground anchor method based on conditions such as earth pressure applied from the periphery of the pre-reinforcing cutting region 11a. To do. That is, in the present embodiment, the ground anchor method is performed before the pre-reinforcing cutting region 11a is completely exposed from the ground.

  When the ground anchor method is started, an installation process is first performed. That is, in the installation step, a plurality of anchor fixing holes 45 (only one place is shown in FIG. 9 for convenience) are drilled across the pre-reinforcing cutting region 11a and the surrounding ground. Specifically, the fixing hole 45 is formed to have a downward inclination of a predetermined angle θ (for example, 5 to 45 degrees) from the pre-reinforcing cutting region 11a toward the ground.

  Then, the ground anchor 1 is inserted into the fixing hole 45. That is, as described above, the ground anchor 1 has the tendon grip 2 and the tendon 3 as main components, and generates a tensile force on the tendon 3 to reinforce the structure. Most of them are inserted so as to be located in the fixing holes 45.

  More specifically, as shown in FIG. 9A, the ground anchor 1 has a fixing hole 45 in which the fixing length r of the tendon 3 covered by the friction packer 6 and a part of the free length q of the tendon 3 are fixed. The remaining portion of the free length portion q of the tendon 3 and the tendon grip 2 are inserted into the fixing hole 45 so as to be exposed to the shaft 30 side.

  When the ground anchor 1 is inserted into the fixing hole 45 and has a predetermined posture (FIG. 9A), as shown in FIG. 9B, a solidified material J such as a grout material is placed in the friction packer 6. Is injected. That is, a flexible tube 55 formed of resin or the like is inserted into the friction packer 6, and the solidified material J is injected into the friction packer 6 through the tube 55. Then, when the inside of the friction packer 6 is almost completely filled with the solidified material J, the injection of the solidified material J is stopped. That is, the solidified material J filled in the friction packer 6 is filled until it covers a part of the fixing length r of the tendon 3 and the free length q of the tendon 3. Then, the tube 55 is removed from the friction packer 6. As a result, the friction packer 6 expands (expands due to filling of the solidified material J) and presses the inner wall of the fixing hole 45. That is, the ground anchor 1 is fixed in the fixing hole 45 by the expansion pressure of the solidified material J injected into the friction packer 6.

  As described above, since the free-length sheath 5 is isolated from the internal space of the friction packer 6 by the water stop material 23, the solidified material J injected into the friction packer 6 via the tube 55 is removed. It does not flow into the free length sheath 5.

  Then, after the solidified material J injected into the friction packer 6 is completely cured, or during the curing, the process proceeds to the tightening process of the ground anchor 1. That is, when the tightening process is started, first, the pressure receiving plate 46 is inserted from the front end side of the tendon grip 2 as shown in FIG. After that, when it is confirmed that the solidified material J in the friction packer 6 is completely cured, as shown in FIG. 10B, from the tip of the tendon grip 2, a bearing plate 47 and a tightening nut 48 are provided. And the nut 48 is tightened against the tendon grip 2 with a predetermined tool. Specifically, the pressure bearing plate 47 is disposed on the upper portion of the pressure receiving plate 46, and the nut 48 is further tightened on the pressure receiving plate 46 side from above. Then, after tightening with the tool, using a jack-up device (not shown), a force in the pulling direction is applied to the tendon 3, and the nut 48 is further tightened to give a predetermined tension force to the free length q of the tendon 3. .

  When the predetermined tension force is applied to the free length q of the tendon 3, the jack-up device is removed, and the process proceeds to the solidifying process of the free length q. That is, in the solidification step, a solidified material J such as a grout material is injected into the free length sheath 5. Specifically, as shown in FIG. 11A, the solidified material J is filled into the free length sheath 5 through the tube member 7 provided in the grip body 15. When the inside of the free length portion sheath 5 is completely filled with the solidified material J as shown in FIG. 11B, the injection of the solidified material J into the free length portion sheath 5 is stopped.

Then, the solidified material J filled in the free length sheath 5 is completely cured, or the shaft excavation is performed again during the curing. That is, in the ground anchor method of the present embodiment, the shaft excavation that was in the middle of excavation is resumed on the condition that the reinforcement of the pre-reinforcing cutting region 11a by the ground anchor 1 is completed (hereinafter referred to as the post-reinforcing cutting region 11b). . Then, as shown in FIG. 12, the shaft excavation and the installation of the beam are performed until the post-reinforcing cutting region 11b is completely exposed.
Thus, when the construction of the post-reinforcing cutting region 11b is completed, the shield excavator S can be used to cut directly. In addition, it is preferable to perform the cutting of the post-reinforcing cutting region 11b after the solidified material J filled in the free length sheath 5 is completely cured.

  As described above, in the present embodiment, the grip body 15 is provided with the tube member 7 and the outside and the free length portion sheath 5 are communicated with each other via the tube member 7. It is possible to easily inject the solidifying material J such as. That is, in this embodiment, since it is not necessary to form a hole or the like for injecting the solidifying material J into the free length sheath 5 during the execution of the ground anchor method, it is possible to ensure high workability. it can. Similarly, since it is not necessary to form a hole for injecting the solidifying material J in the pressure receiving plate 46 or the like, it is possible to prevent a decrease in strength of the pressure receiving plate 46 due to the formation of the hole or the like. High reliability can be secured.

Further, according to this configuration, after applying a tensile force to the tendon 3, the solidified material J can be injected into the free-length sheath 5. It is possible to harden the free length part q. That is, in the present invention, it is possible to solidify the free length portion q by the action of the solidifying material J while generating a tensile force in the free length portion q to exert the anchor function.
Therefore, even when the ground anchor 1 of the present invention is used for the earth retaining wall 31 of the SEW method, the free length portion q of the tendon 3 is entangled with the face of the shield excavator S while exhibiting the anchor function. Such a problem can be prevented.

  In this embodiment, the friction packer 6 filled with the solidifying material J covers not only the fixing length portion r of the tendon 3 but also a part of the free length portion q, and further the free length portion q is covered with the friction packer. Since the solidified material J is also filled in the free length portion sheath 5 that is isolated from the internal space 6, the engagement force in the pulling direction of the ground anchor 1 can be increased. That is, as described above, the free-length portion sheath 5 has an uneven shape in the axial direction, and the free-length portion q can be solidified by filling the free-length portion sheath 5 with the solidifying material J. Therefore, the engaging force with the ground due to the uneven shape (actually, the engaging force with the solidified material J in the friction packer 6) is increased, and the engaging force in the pulling direction of the ground anchor 1 is increased.

  In the above embodiment, a configuration has been described in which the pipe member 7 is provided in the grip body 15 and the outside and the inside of the free-length portion sheath 5 are indirectly communicated with each other via the pipe member 7. There is no limitation, and the pipe member 7 may not be provided in the grip body 15, and the configuration may be such that the outside and the free length portion sheath 5 are directly communicated with each other.

  In the above embodiment, the configuration in which both ends of the tube member 7 protrude from both ends in the axial direction of the grip body 15 is shown, but the present invention is not limited to this, and both ends of the tube member 7 are connected to both ends of the grip body 15. It may be configured not to protrude from.

  In the above embodiment, in the through hole 21 of the grip body 15, the pipe member 7 is arranged at the center of the through hole 21, and the six tendons 3 are arranged at equal intervals in the circumferential direction of the pipe member 7. Although the structure which arranged the wire member 16 was shown, this invention is not limited to this. For example, as shown in FIG. 13 (a), the six wire members 16 and the pipe member 7 are arranged on the same circumference, or as shown in FIG. 13 (b), the six wire members 16 are fixed. Examples are those that are biased in the range.

In the said embodiment, although the ground anchor 1 was used in order to reinforce the cutting part of the earth retaining wall 31 used for SEW construction method, this invention is not limited to this. That is, in the present invention, the ground anchor 1 may be used for another temporary wall cutting method in the shield method.
For example, other temporary wall cutting methods include the well-known SZ pile method and NOMST (registered trademark) method.
Note that the SZ pile method is a method using a resin molded body 57 formed in the same structure as the H-shaped steel shown in FIG. 14 as a cutting portion, and the NOMST (registered trademark) method is a fiber shown in FIG. This is a construction method using a new material concrete reinforced with resin or the like.

1 Ground anchor 2 Tendon grip (tensile side member)
3 tendon (tensile force transmission member)
5 Free length sheath (space forming member)
6 Friction packer (bag)
7 Pipe member 11 Cutting area 15 Grip body 16 Wire member 21 Through hole 30 Shaft 31 Earth retaining wall 46 Pressure receiving plate 48 Nut 55 Tube G Expansion material J Solidification material S Shield excavator q Free length r Fixing length

Claims (6)

It is a ground anchor that is arranged across the structure and the ground and stabilizes the structure,
A tension-side member disposed on the structure side and partially or entirely exposed to the outside, a tensile force transmission member disposed to straddle the structure and the ground, and a space forming member,
The tension side member has a through hole,
The tensile force transmission member has a long shape, one end in the longitudinal direction is integrally joined to the tensile side member, and a free length in which a tensile force is generated by an external force at a midway position in the longitudinal direction. Part is provided,
The space forming member has a space that covers a part or all of the free length portion of the tensile force transmission member, and the space communicates with the outside directly or indirectly through the through hole of the tensile side member. Is ,
The bag has a deformable bag, and the bag is arranged so as to cover from the other end in the longitudinal direction of the tensile force transmission member to the vicinity of the joint portion between the tensile force transmission member and the tensile member. And the tensile force transmitting member is fixed to the ground by a solidified material injected into the bag body .   An arrangement having a pipe member, the pipe member being inserted through the through-hole, with one end exposed to the outside and the other end exposed in the space of the space forming member The ground anchor according to claim 1, wherein:   The ground anchor according to claim 2, wherein the tensile force transmission member is inserted through the through hole of the tensile side member together with the pipe member.   The ground anchor according to claim 3, wherein the tensile force transmission member includes a plurality of long members, and the plurality of long members are arranged to cover the periphery of the pipe member. . The ground anchor according to any one of claims 1 to 4 , wherein the tension side member is a resin molded body reinforced with long fibers. After inserting the ground anchor in which the tensile side member and the tensile force transmission member are joined in series into the hole for anchor, the solidifying material is injected into the hole from between the ground anchor and the wall surface of the hole, and the tensile force transmission member Fixing the fixing length portion in the hole, applying an external force to the tension side member to generate a tensile force on the free length portion of the tension force transmission member, and directly or directly through the through-hole provided in the tension side member. A ground anchor method characterized by comprising a step of indirect use, injecting a solidifying material into a space covering part or all of the free length portion, and hardening the free length portion where the tensile force is generated. ,
The ground anchor has a deformable bag body, and the bag body covers from the other end portion in the longitudinal direction of the tensile force transmission member to the vicinity of the joint portion between the tensile force transmission member and the tensile side member. Is arranged,
In the step of fixing the fixing length portion in the hole, the tensile force transmitting member is fixed to the ground by a solidified material injected into the bag body .

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